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Electronics/Resistors

Resistor

 * [[Image:Resistors2.jpg|300px]]

A resistor is a block or material that limits the flow of current. The greater the resistance, the lower the current will be, assuming the same voltage imposed on the resistor. The hydraulic analogy of a resistor would be the pipe with water flowing through it. The wider the diameter of a pipe, the higher the water flow through the pipe, assuming the same pressure difference on the terminals of a pipe.

Resistor's Symbol
Resistors have two leads (points of contact) to which the resistor can be connected to an electrical circuit. A symbol for a resistor used in electrical circuit diagrams is shown below.

 * [[Image:Resistor symbol America.svg|60px]]

The endpoints at the left and right sides of the symbol indicate the points of contact for the resistor. The ratio of the voltage to current will always be positive, since a higher voltage on one side of a resistor is a positive voltage, and a current will flow from the positive side to the negative side, resulting in a positive current. If the voltage is reversed, the current is reversed, leading again to a positive resistance.

Resistance
Resistance is a characteristic of Resistor indicates the measurement of current opposition. Resistance has a symbol R measured in Ohm (Ω). The ratio of voltage to current is referred to as Ohm's Law, and is one of the most basic laws that govern electronics.
 * $$R = \frac{V}{I}$$

An ohm is the amount of resistance which passes one ampere of current when a one volt potential is placed across it. (The ohm is actually defined as the resistance which dissipates one watt of power when one ampere of current is passed through it.)
 * $$1 \Omega = \frac{1 \mbox{ V}}{1 \mbox{ A}}$$

Resistance can vary from very small to very large. A superconductor has zero resistance, while something like the input to an op-amp can have a resistance near 1012 Ω, and even higher resistances are possible.

Resistance and Temperature
For most materials, resistance increases with increasing Temperature
 * For Conductor . $$R = R_o (1+nT)$$
 * For Semi Conductor . $$R = R_o e^nT$$

Resistance and Electric Power Loss
Resistance converts Electrical Energy into Heat this causes Electric Energy Loss.
 * $$P_r = I^2 R = \frac{V^2}{R}$$

NOTE : Resistors which dissipate large amounts of power are cooled so that they are not destroyed, typically with finned heatsinks.

If Electric Energy Supply is Pv and Electric Energy Loss is Pr Then, Electric Energy Delivered is
 * $$P = p_v - P_r$$
 * $$P = VI - I^2 R = I (V - IR)$$
 * $$P = VI - \frac{V^2}{R} = V (I - \frac{V}{R})$$

The ratio of Electric Energy Delivered over Electric Energy Supplied indicates the Efficiency of Electric Power Supply
 * $$n = \frac{P}{P_v} = \frac{V - IR}{V} = \frac{I - \frac{V}{R}}{I} = \frac{P_v Cos \theta}{P_v} $$
 * $$n = Cos\theta$$

Resistor's Labeling (See also Identification)
A manufactured resistor is usually labeled with the nominal value (value to be manufactured to) and sometimes a tolerance. Rectangular resistors will usually contain numbers that indicate a resistance and a multiplier. If there are three or four numbers on the resistor, the first numbers are a resistance value, and the last number refers to the number of zeroes in the multiplier. If there is an R in the value, the R takes the place of the decimal point.

 * Examples
 * 2003 means 200×103 = 200kΩ
 * 600 means 60×100 = 60Ω
 * 2R5 means 2.5Ω
 * R01 means 0.01Ω

Cylindrical resistors (axial) usually have colored bands that indicate a number and a multiplier. Resistance bands are next to each other, with a tolerance band slightly farther away from the resistance bands. Starting from the resistance band side of the resistor, each colour represents a number in the same fashion as the number system shown above.

Colour System

 * {| cellspacing="0" cellpadding="4" border="1" width="60%"

 Clue : B.B.ROY of Great Britain was a Very Good Worker. Additional Colours: A gold band in the multiplier position means 0.1, but means a 5% tolerance in the tolerance position. A silver band in the multiplier position means 0.01, but means 10% in the tolerance position.
 * align="center" | Black || align="center" | Brown
 * align="center" | Red
 * align="center" | Orange || align="center" | Yellow
 * align="center" | Green
 * align="center" | Blue || align="center" | Violet
 * align="center" | Grey || align="center" | White
 * style="background-color:black" |
 * style="background-color:brown" |
 * style="background-color:red" |
 * style="background-color:orange" |
 * style="background-color:yellow" |
 * style="background-color:green" |
 * style="background-color:blue" |
 * style="background-color:violet" |
 * style="background-color:gray" |
 * style="background-color:white" |
 * align="center" | 0 || align="center" | 1
 * align="center" | 2
 * align="center" | 3 || align="center" | 4
 * align="center" | 5
 * align="center" | 6 || align="center" | 7
 * align="center" | 8 || align="center" | 9
 * }
 * align="center" | 6 || align="center" | 7
 * align="center" | 8 || align="center" | 9
 * }

Resistor's Construction
The resistance R of a component is dependent on its physical dimension and can be calculated using:

 * $$ R = {\rho L \over A} \; $$

where
 * ρ is the electrical resistivity (resistance to electricity) of the material,
 * L is the length of the material
 * A is the cross-sectional area of the material.

If you increase ρ or L you increase the resistance of the material, but if you increase A you decrease the resistance of the material.

Resistivity of the Material
Every material has its own resistivity, depending on its physical makeup. Most metals are conductors and have very low resistivity; whereas, insulators such as rubber, wood, and air all have very high resistivity. The inverse of resistivity is conductivity, which is measured in units of Siemens/metre (S/m) or, equivalently. mhos/metre.

In the following chart, it is not immediately obvious how the unit ohm-meter is selected. Considering a solid block of the material to be tested, one can readily see that the resistance of the block will decrease as its cross-sectional area increases (thus widening the conceptual "pipe"), and will increase as the length of the block increases (lengthening the "pipe"). Given a fixed length, the resistance will increase as the cross-sectional area decreases; the resistance, multiplied by the area, will be a constant. If the cross-sectional area is held constant, as the length is increased, the resistance increases in proportion, so the resistance divided by the length is similarly a constant. Thus the bulk resistance of a material is typically measured in ohm meters squared per meter, which simplifies to ohm - meter (Ω-m).

 * {| border="1" cellspacing="0"

! colspan="2" align="left" | Conductors Ω-m (Ohm-meter) 1.59×10-8 1.72×10-8 2.44×10-8 2.83×10-8 5.6×10-8 10×10-8 11×10-8 22×10-8 1.50×10-6 (A nickel-chromium alloy commonly used in heating elements) ~10-6 3.5×10-5 ! colspan="2" align="left" | Semiconductors ~103 ~105 ~106 ! colspan="2" align="left" | Insulators ~1010 1010 to 1014 9×1013 1013 to 1016 ~1014 ~1015 5 to 75×1016 ||
 * Silver
 * Silver
 * Copper
 * Copper
 * Gold
 * Gold
 * Aluminum
 * Aluminum
 * Tungsten
 * Tungsten
 * Iron
 * Iron
 * Platinum
 * Platinum
 * Lead
 * Lead
 * Nichrome
 * Nichrome
 * Graphite
 * Graphite
 * Carbon
 * Carbon
 * Pure Germanium || 0.6
 * Pure Silicon || 640
 * Common purified water
 * Pure Silicon || 640
 * Common purified water
 * Common purified water
 * Ultra-pure water
 * Ultra-pure water
 * Pure Gallium Arsenide
 * Pure Gallium Arsenide
 * Diamond
 * Diamond
 * Glass
 * Glass
 * Mica
 * Mica
 * Rubber
 * Rubber
 * Organic polymers
 * Organic polymers
 * Sulfur
 * Sulfur
 * Quartz (fused)
 * Quartz (fused)
 * Air || very high
 * Air || very high
 * }

Silver, copper, gold, and aluminum are popular materials for wires, due to low resistivity. Silicon and germanium are used as semiconductors. Glass, rubber, quartz crystal, and air are popular dielectrics, due to high resistivity.

Many materials, such as air, have a non-linear resistance curve. Normal undisturbed air has a high resistance, but air with a high enough voltage applied will become ionized and conduct very easily.

The resistivity of a material also depends on its temperature. Normally, the hotter an object is, the more resistance it has. At high temperatures, the resistance is proportional to the absolute temperature. At low temperatures, the formula is more complicated, and what counts as a high or low temperature depends on what the resistor is made from. In some materials the resistivity drops to zero below a certain temperature. This is known as superconductivity, and has many useful applications.

(Some materials, such as silicon, have less resistance at higher temperatures.)

For all resistors, the change in resistance for a small increase in temperature is directly proportional to the change in temperature.

Current passing through a resistor will warm it up. Many components have heat sinks to dissipate that heat. The heatsink keeps the component from melting or setting something on fire.

Length
The length of an object is directly proportional to its resistance. As shown in the diagram below, 1 unit cubed of material has 1 ohm of resistance. However, when 4 units are stacked lengthwise and a connection is made to the front and back sides respectively, the total resistance is 4 ohms. This is because the length of the unit is 4, whereas the cross-sectional area remains 1. However, if you were to make connections on the sides, the exact opposite would be true: the cross-sectional area would be 4 and the length 1, resulting in 0.25 ohms total resistance.

Cross-Sectional Area
Increasing area is the same as having resistors in parallel, so as you increase the area you add more paths for current to take.

The resistance of a material is inversely proportional to its cross-sectional area. This is shown in the diagram below, where 1 unit cubed has one ohm of resistance. However, if 4 units cubed are stacked on top of each other in the fashion such that there is 4 units squared of cross-sectional area, and the electrical connections are made to the front and back such that the connections are on the largest sides, the resultant resistance would be 0.25 ohms.

Additional note: There are two reasons why a small cross-sectional area tends to raise resistance. One is that the electrons, all having the same negative charge, repel each other. Thus there is resistance to many being forced into a small space. The other reason is that they collide, causing "scattering," and therefore they are diverted from their original directions. (More discussion is on page 27 of "Industrial Electronics," by D. J. Shanefield, Noyes Publications, Boston, 2001.)

Example
For instance, if you wanted to calculate the resistance of a 1 cm high, 1 cm wide, 5 cm deep block of copper, as shown in the diagram below:

You would first need to decide how it's oriented. Suppose you want to use it from front to back (lengthwise), like a piece of wire, with electrical contacts on the front and rear faces. Next you need to find the length, L. As shown, it is 5 cm long (0.05 m). Then, we look up the resistivity of copper on the table, 1.6×10-8 Ω-meters. Lastly, we calculate the cross-sectional area of the conductor, which is 1 cm × 1 cm = 1 cm2 (0.0001 m2). Then, we put it all in the formula, converting cm to m:

$${0.05 \ \mbox{m} \cdot 1.6 \times 10^{-8} \ \Omega \cdot \mbox{m} \over 0.0001 \ \mbox{m}^2} = {0.08 \times 10^{-8} \ \Omega \cdot\mbox{m}^2 \over 0.0001\ \mbox{m}^2}$$

units m2 cancel:

$${0.08 \times 10^{-8}\ \Omega \over 0.0001}$$

Which, after evaluating, gives you a final value of 8.0×10-6 Ω, or 8 microohms, a very small resistance. The method shown above included the units to demonstrate how the units cancel out, but the calculation will work as long as you use consistent units.

 * Internet Hint: Google calculator can do calculations like this for you, automatically converting units. This example can be calculated with this link:

Properties of the material

 * Wirewound: Used for power resistors, since the power per volume ratio is highest. These usually have the lowest noise.

 * Carbon Film: These are easy to produce, but usually have lots of noise because of the properties of the material.

 * Metal Film: These resistors have thermal and voltage noise attributes that are between carbon and wirewound.

 * Ceramic: Useful for high frequency applications.

Resistors in Series

 * [[Image:Resistorsseries.png]]

Resistors in series are equivalent to having one long resistor. If the properties of two resistors are equivalent, except the length, the final resistance will be the sum of the two construction methods:

 * $$R_{EQ} = \frac{\rho L_{EQ}}{A} = \frac{\rho L_1}{A} + \frac{\rho L_2}{A}$$

This means that the resistors add when in series.

 * $$R_{EQ} = R_1 + R_2 + \cdots + R_n \,\!$$

 * Christmas tree lights are usually connected in series, with the unfortunate effect that if one light blows, the others will all go out (This happens because the circuit is not complete, if a circuit is not complete then the current cannot flow, hence the light bulbs all go out). However, most modern Christmas light strings have built in shunt resistors in parallel to the bulb, so that current will flow past the blown light bulb.

Resistors in Parallel

 * [[Image:Resistorsparallel.png]]

In a parallel circuit, current is divided among multiple paths. This means that two resistors in parallel have a lower equivalent resistance than either of the parallel resistors, since both resistors allow current to pass. Two resistors in parallel will be equivalent to a resistor that is twice as wide:

 * $$R_{EQ} = \frac{\rho L}{A_{EQ}} = \frac{\rho L}{A_1} + \frac{\rho L}{A_2}$$

Since conductances (the inverse of resistance) add in parallel, you get the following equation:

 * $$\frac{1}{R_{EQ}} = \frac{1}{R_1} + \frac{1}{R_2} + \cdots + \frac{1}{R_n}$$

For example, two 4 Ω resistors in parallel have an equivalent resistance of only 2 Ω.

To simplify mathematical equations, resistances in parallel can be represented with two vertical lines "||" (as in geometry). For two resistors the parallel formula simplifies to:

 * $$ R_{EQ} = R_1 \| R_2 = {R_1 R_2 \over R_1 + R_2} $$

Combinations of series and parallel

 * [[Image:Resistorscombo.png]]

Resistors in parallel are evaluated as if in a mathematical set of "parentheses." The most basic group of resistors in parallel is evaluated first, then the group in series with the new equivalent resistor, then the next group of resistors in parallel, and so on. For example, the above portion would be evaluated as follows:

 * $$R_{EQ} = (R_1 \| R_2) + R_3 = {R_1R_2 \over R_1 + R_2} +R_3$$

Resistor variations

 * Variable Resistor or Potentiometer
 * Variable resistors are tunable, meaning you can turn a dial or slide a contact and change the resistance. They are used as knobs to control the volume of a stereo, or as a dimmer for a lamp. The term Potentiometer is often abbreviated as 'pot'. It is constructed like a resistor, but has a sliding tap contact. Potentiometers are used as Voltage Dividers. It is rare to find a variable resistor with only two leads.  Most are potentiometers with three leads, even if one is not connected to anything.

 * Rheostat
 * A variation of the potentiostat with a high current rating, which is used to control the amount of power going through a load, such as a motor.

 * Thermistor
 * Temperature-sensitive resistor, in which the resistance decreases as the temperature rises. They are used in fire alarms, so if things get too hot the current rises and trips a switch that sounds an alarm.

 * LDR (Light Dependent Resistor) or Photoresistor
 * A resistor which changes values depending on the amount of light shining on its surface. The resistance decreases as the amount of light increases. They are used in street lamps, so when it gets dark the current decreases and turns on the street lamp.

Applications

 * Voltage division / Attenuation: Sometimes a voltage will be too large to measure, so a means to linearly reduce the voltage is required. Placing two resistors in series to ground will provide a point in the middle to tap.  Resistor RA is placed between the input voltage and the output node, and the resistor RB is placed between the output node and ground.  This creates a voltage divider to lessen the output voltage.  Typically, the resistors are near the value of ~10kΩ.  The Thevenin model of the circuit gives an output  resistance ROUT = RA||RB. A larger output resistance will more likely be affected by the input resistance of the measuring circuit (this is a desired effect in the transistor biasing circuits).  Placement of the voltage divider should be close to the measuring circuit, to minimize noise (in this arrangement, it will be also lessened Rb/(Ra + Rb) times).   The output voltage of the voltage divider is

 * $$V_{output} = \frac{R_B}{R_A + R_B}V_{input}$$

 * Pull-up / Pull-down: If there is nothing to drive a signal node, the node will be left "floating" (for example, such a situation occurs at the trigger input of a car alarm system when the driver has switched off the internal lamp). This may lead to unintended values being measured, or causing side-effects when the voltage is propagated down the remainder of the circuit.  To prevent this, a relatively high value resistor (usually ~10kΩ to ~1MΩ) is placed between the node and ground (pull-down) or a high voltage (pull-up) to bring the voltage of the "floating" node near to the voltage it is being pulled. A resistive voltage divider is another example where the upper resistor "pulls" the output point up toward the input voltage while the lower resistor "pulls" the output point toward the ground. This idea is evolved in the circuit of a resistive voltage summer (for example, the resistors R1 and R2 of an op-amp inverting amplifier) supplied by two voltages (VIN and -VOUT) having opposite polarities. The two voltage sources "pull" the output point in opposite directions; as a result, if R2/R1 = -VOUT/VIN, the point becomes a virtual ground. Placement of a pull-up or pull-down resistor does not have a significant effect on the performance of the circuit, if they have high resistances.
 * Current limiting / Isolation: In order to protect circuits from conditions that may cause too much current in a device, a current limiting resistor is inserted in the middle of the circuit. A digital input to a microcontroller  may benefit from a current limiting resistor.  The inputs to modern microcontrollers have protection circuitry built in that will protect the input from an overvoltage condition, provided that the current is small enough.  For instance, a common microcontroller will be capable of withstanding 20mA.  If there are 12V nets on a circuit board, or in a system, the digital input will benefit from a 350Ω resistor (refer to calculation below).  Usually a slightly larger resistance is used in practice, but too large of a resistor will cause noise, and may prevent the input from being able to read the voltage.  It is good practice to place the resistor as close as possible to the microcontroller input, so that an accidental short on the board will mean that the microcontroller input is likely still protected.

 * $$R = \frac{12V}{20mA} = 600\Omega$$

 * Line termination / Impedance matching: The properties of an electric wave propagating through a conductor (such as a wire) create a reflection, which can be viewed as unwanted noise. A reflection can be eliminated by maximizing the power transfer between the conductor and the termination resistor.  By matching the resistance (more importantly the impedance ), the wave will not cause a reflection.  The voltage of the echo V_r is calculated below in reference to the original signal V_o as a function of the conductor impedance Z_C and the terminator impedance Z_T.  As the name implies, the termination resistor goes at the end of the conductor.

 * $$ V_r = V_o\frac{Z_C - Z_T}{Z_C + Z_T}$$

 * Current sensing: Measurement of a current cannot be done directly. There are three major ways to measure a current: a resistor, a hall sensor, and an inductor.  The hall sensor and inductor use a property of  the magnetic field to sense the current through a nearby conductor.  According to Ohm's law, if a current I flows through a resistor R, a voltage V = R.I appears across the resistor. Therefore, the resistor can act as a passive current-to-voltage converter.  In this arrangement, the resistor should have a very low value (sometimes on the order of ~0.01Ω), so it does not affect the current flow or heat up; however, a smaller value has a lower voltage to read, which means more noise may be introduced.  This contradiction is  solved in the circuit of an active current-to-voltage converter where the resistor may have a significant resistance as an op-amp compensates the "undesired" voltage drop across it (unfortunately, this remedy may be applied only in low-current measurements). The current sense resistor should be placed as close as possible to where the measurement occurs, in order not to disturb the circuit.

 * Filtering: Filtering is discussed later, after an introduction to capacitors and inductors. Filters are best placed close to where measurement takes place.

Specifications
Resistors are available as pre-fabricated, real-world components. The behavior of such components deviates from an ideal resistor in certain ways. Therefore, real-world resistors are not only specified by their resistance, but also by other parameters. In order to select a manufactured resistance, the entire range of specifications should be considered. Usually, exact values do not need to be known, but ranges should be determined.

Nominal Resistance
The nominal resistance is the resistance that can be expected when ordering a resistor. Finding a range for the resistance is necessary, especially when operating on signals. Resistors do not come in all of the values that will be necessary. Sometimes resistor values can be manipulated by shaving off parts of a resistor (in industrial environments this is sometimes done with a LASER to adjust a circuit), or by combining several resistors in series and parallel.

Available resistor values typically come with a resistance value from a so called resistor series. Resistor series are sets of standard, predefined resistance values. The values are actually made up from a geometric sequence within each decade. In every decade there are supposed to be $$n$$ resistance values, with a constant step factor. The standard resistor values within a decade are derived by using the step factor $$i$$

 * $$i = \sqrt[n]{10}; n = 6, 12, 24, 48$$

rounded to a two digit precision. Resistor series are named E$$n$$, according to the used value of $$n$$ in the above formula.

n Values/Decade Step factor i  Series 6            1.47         E6        12             1.21         E12 24            1.10         E24 48            1.05         E48

For example, in the E12 series for $$n = 12$$, the resistance steps in a decade are, after rounding the following 12 values:

1.00, 1.20, 1.50, 1.80, 2.20, 2.70, 3.30, 3.90, 4.70, 5.60, 6.80, and 8.20

and actually available resistors from the E12 series are for example resistors with a nominal value of 120Ω or 4.7kΩ.

Tolerances
A manufactured resistor has a certain tolerance to which the resistance may differ from the nominal value. For example, a 2kΩ resistor may have a tolerance of ±5%, leaving a resistor with a value between 1.9kΩ and 2.1kΩ (i.e. 2kΩ±100Ω). The tolerance must be accounted for when designing circuits. A circuit with an absolute voltage of 5V±0.0V in a voltage divider network with two resistors of 2kΩ±5% will have a resultant voltage of 5V±10% (i.e. 5V±0.1V). The final resistor tolerances are found by taking the derivative of the resistor values, and plugging the absolute deviations into the resulting equation.

The above mentioned E-series which are used to provide standardized nominal resistance values, are also coupled to standardized nominal tolerances. The fewer steps within a decade there are, the larger the allowed tolerance of a resistor from such a series is. More precises resistors, outside of the mentioned E-series are also available, e.g. for high-precision measurement equipment. Common tolerances, colors and key characters used to identify them are for example:

Series Values/Decade  Tolerance  Color Code  Character Code --   E6          6          ±20%       [none]        [none] E12       12          ±10%       silver          K    E24        24           ±5%       gold            J    E48        48           ±2%       red             G     -         -            ±1%       brown           F     -         -            ±0.5%       -             D     -         -            ±0.25%      -             C     -         -            ±0.1%       -             B

Resistor manufacturers can benefit from this standardization. They manufacture resistors first, and afterwards they measure them. If a resistor does not meet the nominal value within the defined tolerance of one E-series, it might still fit into a lower series, and doesn't have to be thrown away, but can be sold as being compliant to that lower E-series standard. Although typically at a lower price.

Series: Resistors that combine in series add the nominal tolerances together.
 * Derivation: $$dR_T = dR_A + dR_B$$

 * Example: For two resistors in series RA = 1.5kΩ±130Ω and RB = 500Ω±25Ω, the tolerance is 130Ω + 25Ω, resulting in a final resistor value RT = 2kΩ±155Ω.

Parallel: Resistors that combine in parallel have a combined tolerance that is slightly more complex.
 * Derivation: $$dR_P = \frac{dR_A R_B^2 + R_A^2 dR_B}{(R_A+R_B)^2}$$

 * Example: For two resistors in parallel RA = 1.5kΩ±130Ω and RB = 500Ω±25Ω.

Power Rating
Because the purpose of a resistor is to dissipate power in the form of heat, the resistor has a rating (in watts) at which the resistor can continue to dissipate before the temperature overwhelms the resistor and causes it to overheat. When a resistor overheats, the material begins to melt away, which will cause the resistance to increase (usually), until the resistor breaks.

Operating Temperature
Related to power rating, the operating temperature is the temperature that the resistor can continue to operate before being destroyed.

Maximum Voltage
In order to avoid sparkovers or material breakdown a certain maximum voltage over a resistor must not be exceeded. The maximum voltage is part of a resistor's specification, and typically a function of the resistor's physical length, distance of the leads, material and coating.

For example, a resistor with a maximum operating voltage of 1kV can have a length in the area of 2", while a 0.3" resistor can operate under up to several tens of volts, probably up to a hundred volts. When working with dangerous voltages it is essential to check the actual specification of a resistor, instead of only trusting it because of the length.

Temperature Coefficient
This parameter refers to the constant in which the resistance changes per degree Celsius (units in C-1). The change in temperature is not linear over the entire range of temperatures, but can usually be thought of as linear around a certain range (usually around room temperature). However, the resistance should be characterized over a large range if the resistor is to be used as a thermistor in those ranges. The simplified linearized formula for the affect on temperature to a resistor is expressed in an equation:

 * $$R = R_0 [1+\alpha(T-T_0)]$$

Capacity and Inductance
Real world resistors not only show the physical property of resistance, but also have a certain capacity and inductance. These properties start to become important, if a resistor is used in some high frequency circuitry. Wire wound resistors, for example, show an inductance which typically make them unusable above 1kHz.

Packaging
Resistors can be packaged in any way possible, but are divided into surface mount, through hole, soldering tag and a few more forms. Surface mount is connected to the same side that the resistor is on. Through hole resistors have leads (wires) that typically go through the circuit board and are soldered to the board on the side opposite the resistor, hence the name. Resistors with leads are also used in point-to-point circuits without circuit boards. Soldering tag resistors have lugs to solder wires or high current connectors onto.

Usual packages for surface mount resistors are rectangular, referenced by a length and a width in mils (thousands of an inch). For instance, an 0805 resistor is a rectangle with length .08" x .05", with contacts (metal that connects to the resistor) on either side. Typical through hole resistors are cylindrical, referenced either by the length (such as 0.300") or by a typical power rating that is common to the length (a 1/4W resistor is typically 0.300"). This length does not include the length of the leads.

Wikibooks

 * Circuit Idea: Passive voltage-to-current converter shows how the bare resistor can act as a simple voltage-to-current converter.

Wikipedia

 * Voltage-to-current converter builds consecutively the passive and active versions of the voltage-to-current converter.
 * Current-to-voltage converter is dedicated to the passive and active versions of the inverse current-to-voltage converter.

Further Readings

 * Resistors in Series and Parallel: Electronics for Beginners

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Electronics/Resistors


text:
Wikibooks talk:Physics bookshelf/Ranking discussion

wow! you've been busy. I like it! Theresa knott 22:08, 17 Mar 2004 (UTC)

I don't think that "Linear Algebra" should fall after calculus, at the same level as differential equations. That's just me. --Whiteknight (talk) (projects) 19:18, 17 July 2006 (UTC)


text:
Microeconomics

Preface
The goal of this book is to explain how people interact economically, understanding the relationship between people, supply and demand, markets, and efficiency. We will do this by first understanding the nature of the basics concepts of microeconomics, then proceeding to the application of the concepts in specific types of situations.

Readers are expected to have an understanding of arithmetics as well as basic differential calculus. Where needed, we use R for statistical programming. The graphics are also created using R, the needed code can be revealed by clicking on the graphic.

Table of Contents

 * 1) /Definition/
 * 2) /Goods and Scarcity/
 * 3) /Economic Systems/
 * 4) /Supply and Demand/
 * 5) /Opportunity Cost/
 * 6) /Perfect Competition/
 * 7) /Monopolistic Competition/
 * 8) /Oligopolistic Competition/

title: Microeconomics


text:
Talk:Cell Biology/Introduction/Cell size

Typo?
"1 µm Diameter of human nerve cell process" Huh? Why's the word process tacked onto the end there?
 * I'm not sure of the history, but it is traditional to call the microscopic appendages of neurons "processes"; it is a general term that includes dendrites and axons. see this

Size of Amoebae
Amoebae are usually much larger than 90 micrometres, if you mean the genus, and show an enormous range in size if you don't, with many much smaller than that listed. What kind of amoebae are you talking about?

The value of 90 µm for an amoeba that was originally in this table had no additional details provided.

This page says Rhizamoeba flabellata has "a very large range of size", they say 50-500 microns.

This page says:

 * The amoebae that most people will be familiar with is Amoeba proteus or Chaos carolinense the so called "giant amoebae".

This protist website says Amoeba proteus can be up to 600 microns.

This page gives several published references for Chaos species in the size range from 700 microns to over 1 mm. JWSurf 13:33, 18 Mar 2004 (UTC)

--According to the Mimivirus wikipedia page, later discovery referenced mimivirus at 800 nm, not 400.


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Electronics/RC

Introduction
An RC circuit is short for 'Resistor-Capacitor' circuit. A capacitor takes an infinite amount of time to discharge through a resistor, which varies with the values of the resistor and capacitor. A capacitor acts interestingly in an electronic circuit, practically speaking as a combination of a voltage source and a variable resistor.

Basics
Below is a simple RC circuit: There is a capacitor in parallel with the resistor and current probe. The way the capacitor functions is by acting as a very low resistance load when the circuit is initially turned on. This is illustrated below: Initially, the capacitor has a very low resistance, almost 0. Since electricity takes the path of least resistance, almost all the electricity flows through the capacitor, not the resistor, as it has considerably higher resistance. As a capacitor charges, its resistance increases as it gains more and more charge. As the resistance of the capacitor climbs, electricity begins to flow not only to the capacitor, but through the resistor as well: Once the capacitor's voltage equals that of the battery, meaning it is fully charged, it will not allow any current to pass through it. All the electricity eventually flows through the resistor. A capacitor's resistance becomes higher and higher as it becomes more charged. Once it is fully charged, for all practical reasons, it has infinite resistance (an open connection). Once the voltage source is disconnected, however, the capacitor acts as a voltage source itself: As time goes on, the capacitor's charge begins to drop, and so does its voltage. This means less current through the resistor: Once the capacitor is fully discharged, you are back to square one:

If one were to do this with a light and a capacitor connected to a battery, what you would see is the following:

 * 1) Switch is hit. Light does not light up.
 * 2) Light gradually becomes brighter and brighter...
 * 3) Light is at full luminosity.
 * 4) Switch is released. Light continues to shine.
 * 5) Light begins to fade...
 * 6) Light is off.

This is how a capacitor acts. However, what if you changed the values of R1? C1? The voltage of the battery? We will examine the mathematical relationship between the resistor, capacitor, and charging rate below.

The Time Constant
In order to find out how long it takes for a capacitor to fully charge or discharge, or how long it takes for the capacitor to reach a certain voltage, you must know a few things. First, you must know the starting and finishing voltages. Secondly, you must know the time constant of the circuit you have. Time constant is denoted by the Greek letter 'tau' or τ. The general formula for percentage change is:

title: Electronics/RC


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File:Electronics RC01.PNG

Electronic diagram drawn in MSPAINT

title: File:Electronics RC01.PNG


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File:Electronics RC02.PNG

A capacitor charging. Drawn in MSPAINT.

title: File:Electronics RC02.PNG


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File:Electronics RC03.PNG

Capacitor Charging. Drawn in MSPAINT.

title: File:Electronics RC03.PNG


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File:Electronics RC04.PNG

Capacitor Charged. Drawn in MSPAINT.

title: File:Electronics RC04.PNG


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Talk:Biochemistry/DNA and RNA

DNA:has a double helix shape. RNA:has a single or alpha strand. (Regarding above, don't dive so shallow in to it.. DNA in all animal/plant/fungi/protist/bacterial enviroments exsists only as a double helix but does occur s a single helix in  many viruses DNA is found as a single strand. Further more RNA will fold back on it's self when ever it can, and not too oftenly will it exsist as a single strand, in most (yes accuratly most.) cases RNA is found it be in a complex folded arrangement that provideds structural and enzymatic activity. Even as a double helix in some viruses!!!)

There are errors in the graphic: the hydrogen bonding in the C-G base pairs are not correct. Dekay 21:00, 20 January 2006 (UTC)

What's the average building blocks(base pairs) of chromosomes
I can't guess it, even DNA itself has a lot of building blocks (an average) Blanc1100 (discuss • contribs) 11:57, 27 November 2019 (UTC)

title: Talk:Biochemistry/DNA and RNA


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Puzzles/Arithmetical puzzles/Hotel Refund

Puzzles | Arithmetical puzzles | Hotel refund

Three men stop at a hotel. There's only one room left, so they agree to share. The desk clerk charges them thirty dollars, and they each give him ten dollars.

Later, the clerk realizes he's over-charged them by five dollars. He gives the bell-boy five one-dollar bills, and tells him to return the money to the three men. The bell-boy keeps two dollars for himself, and gives one dollar to each of the three men.

So, the men paid nine dollars each for the room, for a total of twenty-seven dollars. The bell-hop has two dollars, and that makes twenty-nine. What happened to the other dollar?

And another thing. Two men stop at the same hotel. There's only one room left, so they agree to share. The desk clerk charges them thirty dollars, and they each give him fifteen dollars.

Later, the clerk realizes that once again he has over-charged by five dollars. He gives the bell-boy five one-dollar bills, and tells him to return the money to the two men. The bell-boy, feeling slightly more daring, keeps three dollars for himself, and gives one dollar to each of the two men.

So, the men paid fourteen dollars each for the room, for a total of twenty-eight dollars. The bell-boy has three dollars, and that makes thirty-one. Where did the other dollar come from? And, no, you better not answer that it came from the first puzzle.

solution

(Source: CarTalk is the only place I've heard the second one MikeBorkowski)


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Puzzles/Arithmetical puzzles/Hotel Refund/Solution

Puzzles | Arithmetical puzzles | Hotel refund | Solution

The men paid $27 dollars. The desk clerk has $25 dollars and the bell-hop pocketed $2.

The mistake is expecting that what the men paid and what the bell-boy kept to add up to what the men initially gave the desk clerk. In fact, it is the amount that the room effectively cost them, plus the amount they received back, that should add to $30.

The second puzzle is very similar: $25 is sitting with the clerk, $2 with the men, and $3 with the bellhop. That adds to the required $30.


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Cell Biology/History

Some History of the development of understanding of the Cell
The origin of the idea that living organisms are made of cells is often traced back to observations of thin slices of cork. In 1665 the book Micrographia: Some physiological descriptions of minute bodies made by magnifying glasses was published by Robert Hooke. He wrote:
 * . . . I could exceedingly plainly perceive it to be all perforated and porous, much like a Honey-comb, but that the pores of it were not regular. . . . these pores, or cells, . . . were indeed the first microscopical pores I ever saw, and perhaps, that were ever seen, for I had not met with any Writer or Person, that had made any mention of them before this. ..

We now know that the "cells" Hooke observed were an indication of the cellular structure of multi-cellular organisms. During the 1670s, Antony van Leeuwenhoek used microscopes to observe sperm, red blood cells, and protozoa. While many cells are about 10 microns in diameter, some protozoa are visible to the naked eye, reaching over 1 millimeter in length. Leewenhoek is the inventor of the microscope. Thus, while it is true that the small size of most cells made it difficult to develop the theory that all living organisms are composed of cells, it was also difficult to recognize that living cells have certain functional components such as the nucleus and a surface membrane that allow cells to exist as the basic functional components of all living organisms. In 1833 Robert Brown published a report describing microscopic observations of plant cells in which he used first used the term "cell nucleus":
 * In the compressed cells of the epidermis the nucleus is in a corresponding degree flattened; but in the internal tissue it is often nearly spherical, more or less firmly adhering to one of the walls, and projecting into the cavity of the cell.

Such observations of the microscopic cellular components of cells helped make it possible for	Schleiden and Schwann to propose a cell theory specifying that nucleated cells are key structural and functional units in plants and animals (1832-1838). However, they did not understand cell reproduction. About this time microscopists such as the Belgian botanist Barthelemy C. Dumortier observed and reported the binary fission of cells. By 1879 the zoologist Walther Flemming was using chemical staining of "fixed" cells to allow clear visualization of chromosomes during cell division.

During the 1890s, Ernest Overton, developed a theory of lipid membrane structure and function, based largely on the osmotic properties of cells. Visualization of lipid bilayer membranes at the surface of cells had to wait until the development of electron microscopy.

<< | Size of cells

Cell Biology | ../Introduction/

title: Cell Biology/History


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Template:CellBio

 Cell Biology  | Introduction | Types of cells | Parts of the cell | Cell division | Gene expression and translation /Templates

title: Template:CellBio


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Talk:Arabic/Arabic alphabet (by group)

Untitled
I was thinking a fun exercise would be to get people to write English words in Arabic. This would be useful because 1) people don't have an English vocabulary 2) it would help them dissociate writing system from spoken languages (although this isn't always possible). Of course we could be cheeky and say, "since we don't know any arabic words, let's borrow a few from English", those being Alcohol, algorithm, etc, etc. Maybe we could even have them read an English sentence like: اف يو كن ريد ثيس، يو رد اربيك  (this is meant to say "if you can read this, you can read arabic")

Anyone care to propose a list of exercise-words? -- Kowey 17:52, 18 Mar 2004 (UTC)

Arabic letter size
Is there any possibility in increasing the arabic letter size? It's really hard to copy even with the text sized turned up.

Maybe also any chance of a printable "copy along" page like those in most hiragana/katakana self learn books?

 * Well... i tried, but cranking up the font size doesn't seem to make a difference (i.e. from +2 to +5 is the same). Maybe somebody else knows how? Can't help you on the "copy along" pages... my Arabic book doesn't show how to write the letters.  I've sort of given up on learning the language for now though.  Looks like somebody else will have to take over.  -- Kowey 08:08, 2 Feb 2005 (UTC)

 * Fixed. -- Kowey 13:50, 19 Feb 2005 (UTC)

Isolated
An anonymous editor (hi!) made some changes to the table: but the formatting to these changes is messed up, so it would be useful to correct it first. Also, I've recently set aside the Arabic, but I think the point of the extra _ is to show context, i.e. where other letters go. It is not intended to represent the letter shape itself. But maybe I misunderstood your comment. Best -- Kowey 10:39, 23 October 2005 (UTC)

title: Talk:Arabic/Arabic alphabet (by group)


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User:Alex S~enwikibooks

My name is Alex, and I am interested in electronic engineering.

title: User:Alex S~enwikibooks


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Electronics/Static Electricity

Static Electricity
This is a rough draft.

''As this is a book, it should have historical stories and stuff to make it more interesting. Greeks and amber in this section, for instance.''

When a solitary atom has the same number of electrons and protons, it has no overall charge. The individual charges cancel out. It is said to be neutral.

An atom that has more electrons than protons is negatively charged. The atom will have a tendency to attract other particles that have a positive charge, and repel particles with a negative charge.

An atom that has less electrons than protons is positively charged. The atom will attract negative particles (like solitary electrons or negatively charged atoms) and repel positive particles (like solitary protons or positively charged atoms).

If a solitary proton and electron are placed near each other (or even far away, as long as nothing else is nearby), they will move closer together, until the electron becomes "attached" to the proton and they form a hydrogen atom. An atom of metal that is positively charged (missing electrons) and a free electron will behave the same way.

The same goes for macroscopic objects. A metal sphere that has a significant amount of atoms that have the same number of electrons and protons is neutral. Also, if there are several atoms that are positively charged or negatively charged, it is said that the whole object is charged. This may not be noticeable if only a few atoms on the object are charged.

Charged metal spheres will attract and repel each other according to the same rules as individual particles.

A solitary metal sphere with an excess of electrons will tend to have the extra electrons spread out evenly across the surface of the sphere (not in the interior). This is because the electrons repel each other, and try to get as far apart as possible. On a positively charged sphere, the positive charge (absence of electrons) also spreads evenly across the surface due to its lack of electrons. (Talk about the neat shielding properties of Faraday cages) In the space inside to the sphere there is no charge.

In the case of insulating spheres charge does not move throughout the object, it just sits there. The electrons in this object are not constantly moving from atom to atom, so the empty holes have no way to be filled by their neighbors.

A Van de Graaff generator is basically a pump for electrons (or a "charge pump"). It uses the triboelectric effect to take electrons from one conductor and deposit them on another. The triboelectric effect is caused when two different materials are brought into contact and then separated. One material will have more of a tendency to attract extra electrons, and some of the electrons will transfer from one material to the other. The Van de Graaff generator accomplishes this with a silk or rubber belt held tightly between two rollers of different materials. As the belt comes into contact with one roller and then separates, it picks up charge from the roller. When it comes into contact with the other roller and then separates, it deposits the charge.

It thus makes one roller positively charged and the other negatively charged. The electrons are supplied to one roller and extracted from the other by metal brushes, connected to the large conductors. This creates a voltage between the conductors, due to their distance.

(Should we really be going into so much detail about it though?... I guess as an example of a very basic electric circuit, it is a good example.  Maybe we could just link to Wikipedia triboelectric effect?  That's the thing I don't like about wikibooks.  You have to provide all of the background instead of just directing them to it.)

title: Electronics/Static Electricity


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Electronics/Formulas

Conductor's Properties

 * Voltage
 * $$V = \frac{W}{Q}$$

 * Current
 * $$I = \frac{Q}{t}$$

 * Energy
 * $$E = \frac{W}{t} = \frac{W}{Q} \frac{Q}{t} = V \cdot I$$

 * Conductance
 * $$Y = \frac{I}{V} = \frac{1}{R}$$

 * Resistance
 * $$R = \frac{V}{I} = \frac{1}{Y}$$

Resistance and Temperture
Resistance of a conductor increase with increasing temperature
 * For Conductor
 * R = Ro + N T

 * For Semi Conductor
 * $$R = R_o e^NT$$

Ohm's Law

 * Resistance
 * $$R = \frac{V}{I}$$

 * Voltage
 * $$V = I \cdot R$$

 * Current
 * $$I = \frac{V}{R}$$

 * Power
 * $$P = I \cdot V$$

Power Delivered
Electric Power delivered through resistive network is equal to Electric Power Supply minus Electric Power Loss as Heat through resistance of the resistive network

 * Electric Power Supply
 * $$P_v = I V$$

 * Electric Power Loss
 * $$P_r = I^2 R = \frac{V^2}{R}$$

 * Electric Power Delivered
 * $$P = P_v - P_r$$
 * $$P = IV - I^2 R = I (V - IR)$$
 * $$P = IV - \frac{V^2}{R} = V \left ( I - \frac{V}{R} \right )$$

Work Done

 * $$W = P \cdot t$$

 * $$W = F \cdot s$$
 * $$W = F \cdot s \cdot \cos \theta$$

title: Electronics/Formulas


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File:Electronics RC05.PNG

Capacitor releasing charge

title: File:Electronics RC05.PNG


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File:Electronics RC06.PNG

Capacitor half-full

title: File:Electronics RC06.PNG


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User:Pilaf~enwikibooks

I'm mostly active in the Spanish Wikipedia, though I write at the English Wikipedia from time to time.

title: User:Pilaf~enwikibooks


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Cookbook:Pea

| Legume The pea (Pisum sativum) is a legume cooked as a vegetable in many cultures. It should not be confused with the pigeon pea, cowpea, or other legumes sometimes referred to as peas. There are many varieties and cultivars, and both the greens and fruits (pods and seeds) are eaten. Often the term "pea" refers specifically to the seeds extracted from the pods, although some varieties have edible pods.

Characteristics
Pea pods and their seeds are typically green, and sometimes yellow or purple. The shoots are green.

Harvest and processing
Fresh immature peas, sometimes called garden peas, are harvested in their pods when tender. The pods may be sold whole and the seeds extracted at home, or they may be commercially seeded and sold frozen or canned. Mature peas, sometimes called marrowfat or field peas, are left to dry in the field. They are then shelled before cooking. Split peas are made by peeling of the outer skin of harvested dried peas before splitting them in half. Sugar peas or mangetout, which include snap peas and snow peas, have edible pods and smaller seeds—these are typically eaten whole.

Pea sprouts are the first few inches of freshly-sprouted peas. Pea greens, also called pea shoots or tendrils, are tender young stems, tendrils, and leaves of the plants. Both sprouts and shoots are used as fresh vegetables.

Uses
Dried peas are often made into a soup or stew or simply eaten on their own. Fresh peas are often eaten boiled and flavored with butter as a side dish vegetable. Fresh peas are also used in pot pies, stews, salads, and casseroles. Sugar peas are used in stir fried dishes.

In the UK, dried, rehydrated and mashed marrowfat peas, known by the public as "mushy peas", are popular, originally in the north of England but now ubiquitously, and especially as an accompaniment to fish and chips or meat pies, particularly in "chippies" or fish and chip shops. They may also be used to make the traditional dish pease pudding. These same peas are also sold in cans, but not mashed. These are sold as "Processed Peas", named after the process of drying, rehydrating, then adding artificial colour and sometimes artificial mint flavouring. Sodium bicarbonate is sometimes added to soften the peas.

In Japan and other Far Eastern countries, such as Thailand, Taiwan and Malaysia, peas are roasted, salted, and eaten as snacks.

title: Cookbook:Pea


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Electronics/TTL

Introduction
TTL stands for Transistor-Transistor Logic. It is the system based on combining transistors in such a way that they can be used for logic gates. Transistors have the capability of becoming parts of very complex devices when combined. An average microprocessor uses upwards of 40 million transistors. Transistors in microprocessors, however, are microscopic as opposed to the discrete components used in consumer electronics and circuitboards.

The NOT Gate
The NOT gate works by inverting the input. The TTL version of the NOT gate contains one transistor, seen below:

 * [[Image:Electronics_TTLNOT.PNG]]

When the input, A, is high (+5V), the base of the transistor is saturated, allowing current to flow from the collector of the transistor to the emitter. Since this is possible, the current does not take the higher resistance path through the output (assuming it has a resistive load attached to it such as an LED). When the input is low (0V), the current has no choice but to flow out of the inverted A output (the A with the line overtop to indicate it is negated). The two resistors in the circuit are for limiting current as to not destroy the transistor, and sometimes may not even be required depending on the transistor.

(note: this image is considered *Resistor-Transistor Logic* The proper TTL representation is below.)

To further explain, the NOT gate has been integrated into a circuit by connecting it to a current probe and a battery. When the switch for the input of the not gate is not hit, the current flows in the path indicated by the red diagram below. The current flows through the resistor because the transistor does not conduct when the base is not saturated.:

However, when the switch is hit, making the input high, the circuit is shorted and current flows directly from one terminal of the battery through the transistor, to the other terminal. This is illustrated further in the next figure: In real logic gates, several more transistors are used in order to stabilize the input and output. Although this may seem like a large hike in complexity and price, creating transistors in ICs is a lot cheaper and easier to do, as they do not have to even have a shell or casing, and are a lot smaller.

title: Electronics/TTL


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File:Idealtemp Engineering Thermodynamics.png

Ideal Gas temperature


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Cookbook:Kohlrabi

| Brassicas

Kohlrabi (also kohl-rabi) is a low and stout biennial. It originated in Germany around 4,000 years ago and is a member of the cabbage family (Gongylodes group). It is a cabbage that was selected for its swollen stems -- in German 'kohl' is cabbage and 'rabi' is turnip and it is so called because it has cabbage-like leaves and a turnip-like bulb above ground.

Varieties include White Vienna and Purple Vienna. Some varieties are food for cattle.

Recipes

 * Kawlata
 * Minestra

Kochbuch/ Kohlrabi

title: Cookbook:Kohlrabi


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Cookbook talk:Kohlrabi

* (cur) (last). . 08:45, 14 Mar 2004. . Secretlondon * (cur) (last). . 09:27, 24 Feb 2004. . Imc (internal link) * (cur) (last). . 09:26, 25 Nov 2003. . Rmhermen * (cur) (last). . 09:24, 25 Nov 2003. . Rmhermen * (cur) (last). . 09:23, 25 Nov 2003. . Rmhermen (missed a ') * (cur) (last). . 09:22, 25 Nov 2003. . Rmhermen * (cur) (last). . m 15:28, 17 Sep 2003. . Menchi (food for cattle) * (cur) (last). . m 04:15, 1 Jun 2003. . Hofoen (lat. author) * (cur) (last). . m 06:24, 5 Nov 2002. . Tarquin * (cur) (last). . m 21:46, 14 Oct 2002. . 63.12.7.185   * (cur) (last). . m 21:45, 14 Oct 2002. . 63.12.7.185   * (cur) (last). . m 23:31, 8 Sep 2002. . Ben-Zin (de: ) * (cur) (last). . 09:41, 5 Jun 2002. . 203.0.230.172   * (cur) (last). . m 05:51, 25 Feb 2002. . Conversion script (Automated conversion) * (cur) (last). . m 04:33, 16 Oct 2001. . Malcolm Farmer (MS Word `smart' quotes removed for non-Micrososft browsers)
 * (cur) (last) . . 08:57, 14 Mar 2004 . . Bevo (added external link)

title: Cookbook talk:Kohlrabi


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Cookbook:Lemongrass

| Spices and herbs

Cymbopogon citriodora West-Indian lemon grass Cymbopogon flexuosus East-Indian lemon grass Cymbopogon winterianus Jowitt Citronella grass Cymbopogon martini

Lemon grass or lemongrass is a perennial herb used in Asian (particularly Thai and Vietnamese) and Caribbean cooking. It has a lemony flavor and can be dried and powdered, or used fresh. Commonly used in teas, soups, and curries it is also suitable for poultry, fish and sea food.

There are over 50 species of Cymbopogon. The East-Indian lemon grass (Cymbopogon flexuosus) is native to India, Sri Lanka, Burma and Thailand while the West-Indian lemon grass (Cymbopogon citratus) is assumed to have its origins in Malaysia. While they both can be used interchangeably C. citratus is more suited for cooking. In India C. citratus is used both as a medicinal herb and in perfumes.

Other species used in the perfume industry are Cymbopogon martini distilled into palmarosa oil and citronella grass (Cymbopogon winterianus Jowitt).

title: Cookbook:Lemongrass


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Cookbook talk:Lemongrass

* (cur) (last). . m 09:01, 19 Jun 2003. . Heron (wikified) * (cur) (last). . 08:05, 11 Mar 2003. . Jacquez (basic description & use)
 * (cur) (last) . . 05:25, 19 Jan 2004 . . Sbyholm (Added more information)

title: Cookbook talk:Lemongrass


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Cookbook:Okra

Okra is also known as lady fingers, gumbo and, in south Asia, India, Nepal and some other countries, as bhindi (and, less commonly, bamia and bindi). Gumbo is also the name of a stew that usually contains okra.

Okra grows in an elongated, lantern shape vegetable. It is a fuzzy, green, ribbed, fibrous pod. It is usually two to four inches long, but it can grow to fourteen inches long. When cut open on the bias, it has rows of tiny seeds and a slimy or sticky texture.

The seeds of an okra can be toasted, ground, and served as a coffee substitute. Okra is common in African, Middle Eastern, Greek, Turkish, Indian, Caribbean, and South American cuisines. Okra is commonly associated with US Southern, Creole, and Cajun cooking since it was initially introduced into the United States in the US South. Okra is one of the most popular vegetables in late 20th century Japanese cuisine.

Along with roux, okra is the normal thickening agent in gumbo.

The best okra, like almost all vegetables, is young and fresh right out of the garden. Okra is easy to grow, prolific, and beautiful. Okra is in the hibiscus family, and has very pretty yellow flowers. Okra gets very woody when it gets too mature, so be sure to pick often, even if you stick it in the refrigerator for a few days until you are ready to eat it. Fresh okra should be used the same day that it was purchased or stored paper bag in the warmest part of the refrigerator for 2-3 days. Severe cold temperatures will speed up okra decay.

Steam okra until tender, either whole or sliced about ½ inch thick. Smother it with butter. Okra can also be boiled with tomatoes or fried in a cornmeal batter. Okra can be pickled. Okra is a sensitive vegetable and should not be cooked in pans made of iron, copper or brass since the chemical properties turns okra black.

Slime
If you are not fond of the slime characteristic to okra, you can take a few measures:

 * Before cooking the okra, trim off the ends, being careful not to cut so deeply you expose hollow space inside and seeds.
 * Avoid washing the okra pods too early before you cook.
 * Do not puncture the okra capsule before or during cooking.
 * Do not overcook the okra.
 * Cook the okra with tomatoes or some other acid.

title: Cookbook:Okra


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Cookbook talk:Okra

* (cur) (last). . m 23:26, 20 Feb 2004. . Crayfish * (cur) (last). . 07:13, 6 Feb 2004. . WormRunner (change genus, taxobox) * (cur) (last). . m 08:01, 7 Aug 2003. . Jimbreed (typo) * (cur) (last). . 22:09, 3 May 2003. . Zoe (photo) * (cur) (last). . m 00:19, 19 Jan 2003. . Tarquin * (cur) (last). . m 19:44, 18 Jan 2003. . Arthur3030 * (cur) (last). . 18:57, 18 Jan 2003. . Koyaanis Qatsi * (cur) (last). . 18:47, 18 Jan 2003. . 205.188.209.12   * (cur) (last). . 18:44, 18 Jan 2003. . Zoe (Trying to make an encyclopedia article out of this) * (cur) (last). . 18:38, 18 Jan 2003. . 65.96.131.126   * (cur) (last). . 17:00, 27 Nov 2002. . 65.96.131.145 (Okra - an oft-slandered vegetable)
 * (cur) (last) . . m 06:54, 21 Feb 2004 . . WormRunner (links to authors and centering)

When my dad makes Bhindi (an indian dish), it is, as you say, slimy. It is also delicious. I think that the paragraph on "Slime" is too western a perspective (for an oriental/african food) and should probably be redone.

 * looks like some anon put in the slime thing and it was toned down by a bunch of people. I'm going to change it.

MisterSheik 06:42, 16 Jun 2005 (UTC)

How is okra "less commonly" known as "gumbo"? Last I checked, that's how it's known to quite a large number of people in Louisiana, the Carribean, and Africa. Do we not count? :) Alainna 06:11, 26 November 2006 (UTC)

title: Cookbook talk:Okra


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Cookbook:Chive

Chives are a member of the onion family grown for their stems, which are used as an herb.

Characteristics
Growing in bunches, chives consist primarily of thin, hollow, green stems. Unlike garlic chives, chive stems are rounded instead of flattened and have a mild onion rather than garlic flavor. Chives also produce edible purple flowers.

Selection and storage
When selecting fresh chives, look for bright green and unblemished stems. They shouldn't be wilted or slimy. Store them in the fridge in an airtight container for up to a few days. Dried chives are also available, but they are much less vibrant.

Use
Due to their mild aromatic flavor and delicate texture, chives are commonly used as garnish. For example, they may be very finely sliced or chopped so they appear as small green speckles. Because they are so delicate and vibrant, avoid long or high-heat cooking.

title: Cookbook:Chive


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Cookbook:White Radish

White radish or Asian radish is a large group of radishes common to Southeast and East Asian cuisines.

Characteristics
While there are a few different varieties of white radish, they are all very similar, with crisp, white, juicy flesh and a milder flavor than that of red radish. The daikon or Japanese variety is typically large and elongated, somewhat resembling a carrot. The mu or Korean variety is rounder, with a shape somewhat like that of a potato.  Cantonese lo bak is considered a little "spicier", though not much. The chonggak variety is small, with a wider bottom than top. When cooked, white radish mellows out in flavor.

The radish greens are also edible, with a slightly peppery flavor.

Selection and storage
When selecting white radishes, you want to look for those with firm and heavy flesh with no softness, bruising, sponginess, or wrinkling. If the greens are still attached, they should be bright green and healthy-looking. The root keeps well, wrapped in a paper towel inside a plastic container, for a couple weeks. Make sure to remove the leaves from the root before storage, because they will otherwise sap the root and make it spongy. The leaves will keep in a plastic container for a few days.

Use
White radish is served in a variety of ways, from raw to cooked, and across a variety of cuisines. Cooked, it can be braised, made into cakes, or added to soups and stir-fries. Raw, it can be slivered, ribboned, or grated for garnish or incorporation into salads and other raw preparations. It is also pickled, as in kimchi, danmuji, takuan, and more.

The radish is often peeled before use, though the skin is thin and technically edible.

Substitution
If you can't find any variety of white radish, jicama will provide a similar crisp and watery texture, though the flavor is quite different.

title: Cookbook:White Radish


text:
Cookbook talk:White Radish

* (cur) (last). . m 15:26, 20 Nov 2003. . Cyan (Reverted to last edit by Akira742) * (cur) (last). . 15:22, 20 Nov 2003. . 203.108.4.66   * (cur) (last). . 15:18, 20 Nov 2003. . 203.108.4.66   * (cur) (last). . 15:18, 20 Nov 2003. . 203.108.4.66   * (cur) (last). . 15:16, 20 Nov 2003. . 203.108.4.66   * (cur) (last). . 22:03, 1 Nov 2003. . Akira742 * (cur) (last). . 20:04, 29 Oct 2003. . 130.54.12.243 (+ja:) * (cur) (last). . m 17:53, 17 May 2003. . Synthetik (+Kanji) * (cur) (last). . m 15:14, 7 Feb 2003. . Arthur3030 (oops. linked supermarket) * (cur) (last). . 15:13, 7 Feb 2003. . Arthur3030 (giant white radish)
 * (cur) (last) . . 01:36, 13 Mar 2004 . . Chris 73 (added pictire of daikon)

title: Cookbook talk:White Radish


text:
Field Guide

 * Animal Tracks
 * Bats
 * Birds
 * Clouds
 * Constellations
 * Frogs
 * Insects
 * Beetles
 * Butterflies and Moths
 * Caterpillars
 * Dragonflies and Damselflies
 * Mammals
 * Mushrooms
 * Newts and Salamanders
 * Reptiles
 * Rocks and Minerals
 * Scat
 * Scorpions
 * Sea Mammals
 * Sea Shells
 * Sharks
 * Snakes
 * Snakes of Europe
 * Spiders
 * Plants
 * Cacti
 * Edible Wild Plants
 * Mosses
 * Lichens, Liverworts, and Mosses
 * Trees
 * Wildflowers

title: Field Guide


text:
Cookbook:Coconut

| Basic Foodstuffs

Coconuts are large tropical seeds with many uses in cooking.

Characteristics
When young, coconuts are smooth and green on the outside. The inside contains a thin layer of white, jelly-like flesh with a good amount of clear liquid, called coconut water. As the coconut ages, the outside becomes brown and fibrous, the amount of coconut water decreases, and the inner flesh thickens and hardens. The flavor of the meat is mild but aromatic.

Mature coconut flesh is edible as is, but it is often separated from the hull and processed to make various coconut products. When shredded and processed with hot water, the flesh yields coconut milk, a rich, white liquid. When this is allowed to separate and thicken, it produces coconut cream, which has a much lower water content. When pressed, the flesh yields coconut oil. It can also be shaved or shredded—either sweetened or unsweetened—to make various grades of dried coconut. Coconut syrup can be produced by cooking the milk with sugar.

Seasonality
As the tree fruits regularly, coconuts are in season year-round.

Selection and storage
When choosing coconuts, you'll want to give them a shake to make sure they still contain liquid—if they do not, they are too dry. You also want to avoid cracked or moldy coconuts. Mature coconuts are very hardy and can be kept at room temperature. Young coconuts can also be kept at room temperature, but they only last about a week before the inside may start to ferment. Dried coconut can be kept in an airtight container at room temperature away from light, heat, and moisture. Because of the high fat content, it will eventually go rancid.

Preparation
When working with whole coconuts, some preparation is required. For young coconuts, use a large, sharp knife or cleaver to make a square cut in the top, and remove it to leave an opening. The water can then be poured out, and the soft flesh can just be scooped out with a spoon. With mature coconuts, the first step is to punch holes in the eyes to drain out any coconut water. The next step is to use a mallet to crack open the coconut, then use a peeler or knife to peel the brown skin from the flesh.

Use
With all its different components and products, coconut is used in a wide range of dishes. The shoots can be eaten as hearts of palm, and the young coconut flesh and water are often consumed on their own. The milk and cream are usually cooked in both sweet and savory dishes, such as curries and puddings, where they add a rich character. Coconut oil has some similar characteristics to butter, which makes the oil a good dairy-free substitute. Dried coconut is often used in patisserie and confectionery, where it adds richness, flavor, texture, and aesthetic character.

title: Cookbook:Coconut


text:
Russian/Lesson 3

 * Я студeнт.

This means "I am a student" in Russian.

 * "Я" means "I".
 * "студе́нт", as you may remember from Lesson 1, means "student".
 * Russian does not distinguish "a student" from "the student"; that is, it does not use articles ("a", "an", "the"). So the above sentence could also be translated as "I am the student."
 * Russian does not use the verb to be in the present tense. Instead, a dash separates the subject of the sentence from the predicate (but the dash is not put between a pronoun and a verb).

Examples

Russian has eight personal pronouns altogether:

Grammar vs. vocabulary; "getting by" vs. "good Russian"
Are you learning Russian to "get by" on a one-week business trip to Moscow? Or do you want to learn "good Russian"?

To "get by" you need basic grammar, but not the byzantine grammar of "good Russian." You could treat all nouns as if they were masculine, and all verbs as if you are the person doing the action, and Russians would understand your meaning. But you should read over the many grammar rules so that you have a clue what Russians are saying. E.g., you should be able to recognize when a Russian uses the prepositional case, even if you only use the nominative case.

If you want to marry a Russian, learn good Russian. Russians (and people all over the world) are impressed by good language skills. Note that in English the words "conjugate" (to produce the different forms of a verb) and "conjugal" (relating to marriage) come from the same root word (meaning "to join together"). In other words, Russians think that someone who can say "I study, you study, he studies, she studies, we study, they study" correctly (in Russian) will make a good spouse!

Native speakers learn grammar as children, by listening to adults talk, and being corrected by their peers. A child who reads a lot, and whose parents speak correctly, doesn't need to learn grammar rules. As an adult learning Russian, you'll learn best if a native Russian listens to you and corrects your mistakes. But the grammar rules will act as shortcuts, to help you learn faster.

When learning anything, some people are auditory learners, some are visual, and some are movement learners. (See "The Open Mind," by Dawna Marcova, for more about this.) But all three learning styles are needed for organizing and committing to long-term memory. You may prefer to hear spoken Russian, or see written Russian, or (for movement learners) write a Russian word and then write how it sounds in English. You may need to do an activity, such as cooking dinner, to pay attention. But all of us need to do all of these things to learn well.

Gender
You may guess correctly that the correct way to say "He is a student" in Russian is "Он студент." However, things change a bit when talking about "она". As in many Indo-European languages—including English until several hundred years ago—gender is an important feature of Russian grammar. Every noun, as well as the three third-person singular pronouns, has a characteristic gender: masculine, feminine, or neuter.

Masculine nouns end in a consonant. Remember that й is a consonant.

Feminine nouns end in а or я.

Neuter nouns end in о or е.

Nouns ending in ь can be masculine or feminine. Nouns ending in ь that describe abstract concepts are generally feminine, but otherwise there's no rule; you just have to memorize these words.

quiz
{Она Арти́стка - masculine + feminine - neuter
 * type=""}

Formal and Informal
Russians differentiate between formal and informal social relationships. Two words translate to "you": Вы (pronounced "vee" but make it short, don't draw out the vowel) is how you say "you" to a teacher, police officer, etc. Ты (pronounced "tee") is how you say "you" to a friend or family member. Russians are more formal than Americans, so if in doubt use Вы!

Вы is also "you plural" or "you all." In other words, you address a superior person as if he or she were several people.

The greeting здравствуйте (formal) and здравствуй (informal) has two forms.

The word "your" also comes in formal and informal: ваш (formal) and твой (informal).

quiz
{Привет ! Меня зовут Андрей. А тебя? - formal + informal
 * type=""}

{Здравствуйте! Меня зовут Петр, а Вас? + formal - informal
 * type=""}

Russian names
Russians use three names: first name, or имя; middle or patronymic name, or отчество, which is their father's first name plus a suffix meaning "son of" (ович) or "daughter of" (овна); and the last name or family name, or фамилия. Women's last names add an а to the masculine form of the name.

To address a Russian formally, don't use "Mr." or "Ms." Instead, address the person using his or her first name and patronymic.

Russians use relatively few first names. There are only a dozen or so men's first names, and maybe three dozen women's first names. Creativity in baby-naming isn't encouraged.

Russians also use diminutives or nicknames. Each name typically has a version used by your best friend, another used by your other friends, another used by your teachers, another used by your grandmother, another used when you are scolded, etc.

Noun Cases
English uses word order to indicate a sentence's subject and object. E.g., "Bob eats lunch" and "Lunch eats Bob" have different meanings in English. Word order is less important in Russian. Instead, meaning is conveyed by suffixes. It would be like an eaten lunch becoming "lunchoo," so you could say "Bob eats lunchoo" or "Lunchoo eats Bob," and still make it clear that it's the lunch that is eaten (not Bob).

This would be straightforward enough if there were simply one case for the subject of a sentence, and a second case for the object of the sentence. Instead, Russian has six cases, conveying such meanings as where you are vs. where you're going, or whether the object of the sentence is animate or inanimate!

Nominative case
The primary case, used for the subject of the sentence ("Bob"), is called the nominative case. This is the case you find in dictionaries.

Accusative case
"Lunch" is the direct object of "Bob eats lunch." The direct object is used in the accusative case. Inanimate masculine and neuter nouns in the accusative case are the same as nouns in the nominative case. Feminine nouns change their а or я ending to у or ю, respectively. E.g., "car" is машина (pronounced "masheena") in nominative case, and машину (pronounced "masheenoo")in the accusative case.

Prepositional case
When a sentence contains a complement of location, the noun is in the prepositional case. In general, you add е (pronounced "yeh") to end of the word. E.g., "I live in Michigan" becomes "I live in Michigane." If the word ends in й, а, or я, replace that letter with е. E.g., "She works in Minnesota" becomes "She works in Minnesote."

There are two exceptions to the е ending. Never write ие, instead write ии (yes, Russians pronounce both, like "ee-ee"). The other exception is foreign nouns ending in о, и, or у. These look the same as the nominative case. E.g., Colorado, Kentucky, and Peru don't change.

Nouns in the prepositional case are always preceded by "in" or "about." Each word comes in two versions. If "in" is an activity, or a place where an activity is done (for example, the ballet) use на (pronounced "na"). For other places, use в (pronounced "veh" or pronounced with the next word if it starts with a vowel, e.g., "in Atlante" would be "vatlante").

"About" is о, or, if the following word starts with a vowel, об. There are several cases when "about" is обо, e.g. обо мне.

Куда vs. где
Куда asks "where (whither) are [you/he/she/etc.] going?" It's pronounced "koodá.".

Где asks "where are [you/he/she/etc.]?" I.e., куда is moving, где is static. It's pronounced "gdye," with the d palatalized.

Statements that could answer the question куда are in the accusative case. E.g., "We're driving to St. Petersburg, Florida" would be in the accusative case, if you said it in Russian.

Statements that could answer the question где are in the prepositional case. E.g., "We live in Moscow, Idaho" would be in the prepositional case.

This is easy to remember because the vowels in Куда are у and а—nouns that end in а (feminine nouns) change to у in the accusative case. The vowel in где is е, the letter you add to end nouns in the prepositional case.

Genitive case
The genitive case is used to show possession, negation, and quantity such as numbers. E.g., I have six chairs (У меня есть шесть стульев) is plural both in English and in Russian! It's genitive case.

Genitive nouns
Masculine and neuter nouns form the genitive case the same way: add а at the end. E.g., стол (sing. table) becomes стола́, but столы́ (pl. tables) becomes столо́в. The exceptions are masculine words ending in й or ь add я. if the word ends in a vowel, drop the vowel then add a.

Feminine nouns drop the а and add ы. E.g., лампа (lamp) becomes лампы. The exceptions are if the word ends in я or ь, or for the 7-letter spelling rule, add и.

Genitive adjectives
Masculine and neuter adjectives form the genitive case the same way: change the ending to ого. This is pronounced "ovo"! The exceptions are masculine words ending in й or ь, or for the 5-letter spelling rule with the ending unstressed, change to его (pronounced "yevo").

Feminine adjectives change the ending to ой (rhymes with "boy"). The exceptions are feminine words ending in й or ь, or for the 5-letter spelling rule with the ending unstressed, change to ей (pronounced "yay").

Genitive case of possessive pronouns
The possessive pronouns его́, её, and их (his, hers, theirs) never change.

"I have something"
Genitive case is also used for saying you have something, or you don't have something. To say that you have something, start with У (means by or next to ). Then change the pronoun (я, ты, вы, etc.) to the following:

In many cases, the genitive ого́ ending is irregularly pronounced ovo.

In other words, Russians don't say Ivan has a dacha, but rather say By Ivan is dacha.

"No something"
In Russian, you use genitive instead of nominative with negative word нет n'et "no" when you want to say that there isn't something or one does not have something. If there is none of it, it can't be the subject, right?

Dative case
Dative case is used with the indirect object of a sentence. It is, when people want to say something to her or to give(to sell, to show and etc.) something to him, etc. (for example: He shows to her this beautiful picture (Он пока́зывает ей э́ту прекра́сную карти́ну). Note here the difference between the direct object from earlier and the indirect object: Ivan gives a letter (direct object, accusative case) to his sister (indirect object, dative case; also depending on the vowel. If it is silent or not. But that rarely happens in modern Russian)

Dative case quiz
/Dative case quiz/

Russian lacks "a," "the," and "to be"
Russian lacks the articles "a," "an," and "the." English uses the definite article "the" to indicate a specific place, thing, etc.: "I ate the orange" suggests there was only one orange, or it was special or something. English uses the indefinite articles "a" and "an" to indicate that the following noun is not a specific, e.g., "I ate an orange" suggests there were several oranges.

Russian also lacks the verb "to be," and its conjugations "am," "are," and "is."

Thus the English four-word sentence "I am a student" is just two words in Russian: "Я студент." In written Russian, when a sentence has two nouns in a row, a — is written between the nouns to indicate the verb "to be." E.g., "Tanya is a student" translates to "Таня — студентка."

"This," "these," and "those"
Russian has the adjectives "this" and "these." To "get by" in Russian use это (pronounced "eta") for both "this" (singular) and "these" (plural). To speak "good Russian" it gets confusing. If a word is between "this" (or "these") and the noun ("This is my suitcase") then это doesn't change. But if the noun immediately follows "this" or "these" ("This suitcase is mine") then, if the noun is masculine, это changes to этот (pronounced "etot") ; if the noun is feminine then это changes to эта (pronounced "eta") ; if the noun is neuter then это doesn't change; and if the noun is plural ("these") then это changes to эти (pronounced "etee").

Russian also has the adjective "those": те. This follows the conjugation for 'that', implying that the noun is in a remote location (not here). Masculine is тот, Feminine is та, Neuter is то, and Plural is те.

this these and those quiz
This these and those quiz

Plural nouns
In English we add "s" (or "es") to indicate that a noun is plural. Russian isn't so simple.

Masculine nouns ending in a "hard" consonant add ы. E.g., студент (student) becomes студенты (students). Masculine nouns ending in the "soft" consonants й or ь add и. E.g., словарь (dictionary) becomes словари (dictionaries). If you speak Russian (without writing) you can "get by" without learning this distinction, as ы and и sound similar.

Feminine nouns ending in а change the а to ы. This is not always the case. Sometimes а is replaced by и e.g. груша → груши. Feminine nouns ending in я change the я to и. Thus masculine and feminine nouns follow a similar pattern for plural. Again, if you only want to speak "get by" Russian you can ignore this distinction because a and я sound similar.

Neuter nouns have a different pattern for plural. Neuter nouns ending in o change the o to a. This is not always the case. Sometimes o is replaced by и e.g. яблоко → яблоки. Neuter nouns ending in e change the e to я. Thus, neuter plural nouns look like feminine singular nouns.

Note that these rules are for plural nouns. Plural adjectives follow different rules.

The 7-letter spelling rule
Now it gets complicated. After the letters к, г, х, ш, щ, ж, and ч, always add (or change a or я to) и, not ы. E.g., книга (book) becomes книги (books).

Exceptional plurals
Some masculine nouns drop the last vowel before adding ы or и. E.g., подарок (present or gift) becomes подарки.

Some masculine nouns add a for plural. E.g., дом (house) becomes дома (houses).

Words of foreign origin ending in o, и, or у don't change between singular and plural. E.g., радио means "radio" or "radios." Note that foreign nouns with these endings also don't change in prepositional case (e.g., Colorado, Kentucky, and Peru).

The personal pronouns "he," "she," and "it"
The personal pronouns are straightforward:

"He" (masculine) is он.

"She" (feminine) is она.

"It" (neuter) is оно.

"They" (plural) is они.

Note that in English we use "he" and "she" for animate objects (people and animals) and "it" for everything else, but Russians use "he" for all masculine nouns, "she" for all feminine nouns, and "it" for all neuter nouns. Thus, a car (машина) is always "she" because машина is feminine.

"Whose?"
The English question word "whose" translates to four Russian words, depending on gender:

чей (pronounced "chey") is masculine.

чья (pronounced "chyah") is feminine.

чьё (pronounced "chyo") is neuter.

чьи (pronounced "chyee") is plural.

If you just want to "get by," say "chee" and you'll be right about 50% of the time.

The possessive pronouns "my," "your," "our," "his," "her," and "their"
To learn to conjugate verbs as well as possessive pronouns, memorize the following order of pronouns:

я (I) ты (you, informal) он/она (he/she) мы (we) вы (you, formal and plural) они (they)

In this order, in English the possessive pronouns are "my, your, his, her, our, (no formal your), their." Russian makes this complicated because four of these words change depending on whether the following noun is masculine, feminine, neuter, or plural. Three don't change.

The three possessive pronouns that don't change are "his," "her," and "their." In Russian these are его ("his"), pronounced "yehvo" (not "yehgo"); её, pronounced "yehyo" ("her yo-yo" would sound like "yeh-yo yo-yo"); and их (pronounced "eech," like the German word for "I").

The four possessive pronouns that change are "my," "your" (informal and formal), and "our."

"My" is мой (masculine, pronounced "moy," which sounds vaguely like a New York Yiddish version of "my"); моя (feminine, pronounced "mo-yah"); моё (neuter, pronounced "mo-yo"), and мои (plural, pronounced "mo-ee").

"Your" (informal Ты) is твой (masculine, pronounced "tvoy"); твоя (feminine, pronounced "tvo-yah"); твоё (neuter, pronounced "tvo-yo"), and твои (plural, pronounced "tvo-ee").

"Our" (Мы) is наш (masculine, pronounced "nash," not like "Nashville" but rhymes with "wash"); наша (feminine, pronounced "nasha"); наше (neuter, pronounced "nashyeh"), and наши (plural, pronounced "nashee").

"Your" (formal Вы) is ваш (masculine, pronounced "vash", rhymes with "wash"); ваша (feminine, pronounced "vasha"); ваше (neuter, pronounced "vash-yeh"), and ваши (plural, pronounced "vashee"). A memory aid is "your car is a washing machine." Picture opening the hood of a car and finding a washing machine where the engine should be. "Your car" is ваша машина (sounds like "washing machine").

Adjective endings (nominative case)
Russian adjectives agree with their nouns in gender, number, and case. Here we will learn the adjective endings for gender and number (singular vs. plural). (Cases will be later.)

The dictionary form of adjectives end in ый (pronounced "ee"). This is the ending with masculine nouns. E.g., "new pencil" is новый карандаш (pronounced "no-vee karandash").

With feminine nouns, the adjective ends in ая. E.g., "new car" is новая машина (pronounced "no-vah-yah masheena").

With neuter nouns, the adjective ends in ое. E.g., "new dress" is новое платье (pronounced "no-vo-yeh plat-yeh"). As a memory aid, think of "oh yeah."

With plural nouns, the adjective ends in ые. E.g., "new students" is новые студенты (pronounced "no-vih-yeh studentih"). As a memory aid, think of plural as one masculine and one neuter object. Take the first letter from the masculine ending (ы) and the second letter from the neuter ending (е) and you get ые.

Adjectives with "soft endings" (й or ь) have the same second letter in their endings, but the first letter of the endings change. The masculine ending ый becomes ий, the feminine ending ая becomes яя, the neuter ending ое becomes ее (like the "yeah-yeah" chorus of 1965 Beatles songs), and the plural ending ые becomes ие (maintaining the memory aid that you take a masculine object and a neuter object to get two objects).

5- and 7-letter spelling rules
Recall that with plurals, after the letters г, ж, к, х, ч, ш, and щ, you use и, not ы. This 7-letter spelling rule also applies to adjectives. As a memory aid, ч, ш, and щ are together in the alphabet.

The 5-letter spelling rule is that after the letters ж, ц, ч, ш, and щ, don't write an unstressed o, but instead write e. As a memory aid, ц, ч, ш, and щ are together in the alphabet.

"What?" and "which?"
Что (pronounced "shto," not "chto") and какой both mean "what." As a loose rule, какой means "which." The correct rule is that if a noun follows "what," use какой. If no noun follows "what," use что.

As a memory aid, the following noun's gender and number change какой. Какой precedes masculine nouns, какая precedes feminine nouns, какое precedes neuter nouns, and какие precedes plural nouns. Because что does not modify nouns, it does not change according to gender.

If you just want to "get by," always use что for "what."

Showing Ownership
In English, "my" and "I have" are different, just as "your" and "you have" are different. Russian makes a similar distinction—but it's more complicated.

First, the pronoun is in the genitive case (меня, тебя etc.), which indicates possession/ownership. The preposition used with the genitive pronouns to indicate ownership is У (pronounced "oo"), meaning roughly "with".

The forms are as follows:

"I have": У меня (pronounced "oo meen-yah", meaning roughly "with me")

"You have" (informal): У тебя (pronounced "oo teeb-yah", meaning roughly "with you")

"You have" (formal): у вас (pronounced "oo vas")

"He has": у него (pronounced "oo nee-go", meaning "with him")

"She has": у неё (pronounced "oo nee-yo", meaning "with her")

"We have": у нас (pronounced "oo nas", meaning "with us")

"They have": у них (pronounced "oo neech", meaning "with them")

Thus the question "У тебя есть карандаш?" when interpreted rather literally, means "With you is a pencil?" It is easy to see how this can be correctly interpreted as "Do you have a pencil (with you)?" or even just "Do you own a pencil?"

These three phrases are sometimes followed by есть (pronounced "yehst", meaning "is"). Есть questions the existence of something, e.g., У вас есть синий костюм? ("Do you have a blue suit?").

Verb conjugation, present tense
In English we say, "I study," "you study," "he studies," "she studies," "we study," "they study." Note that some pronouns use "study," while other pronouns use "studies." "Verb conjugation" is how verbs change with pronouns. English has simple two-form verb conjugation for the present tense.

Russian verbs conjugate in six forms, for "I", "you (singular and informal)", "he" and "she", "we", "you (plural and formal singular)" and "they". In addition, Russian verbs conjugate in either of two ways. In other words, some verbs are first conjugation, when others are second conjugation.

All verbs have an infinitive form, which is listed in dictionaries. Typically this form ends in -ть.

First-conjugation verbs usually end in something other than -ить (e.g. in -ать). These verbs conjugate by dropping the ть and replacing it with the following endings:

Second-conjugation verbs usually end in -ить. These verbs conjugate by dropping the -ть and replacing it with the following endings:

Verb conjugation, past tense
Past tense verbs are somewhat simpler. They conjugate with the gender (or number) of the pronoun. Thus, "I understood" changes depending on whether the speaker is a man or a woman. But the verb is the same for "he understood" or for "I understood," where the speaker is a man. "We understood" and "they understood" are the same.

To form a past tense verb, drop the ть and add л (pronounced "l") for masculine pronouns ("I," "you," "he"), ла (pronounced "la") for feminine pronouns ("I," "you," "she"), and ли (pronounced "lee") for plural pronouns (мы, они, "we," "they"). (Neuter subjects can't talk.)

Verb conjugation, future tense
Russian future tense is incredibly more complex in meaning than English future tense. Russian future tense also contains information pertaining to the aspect of the verb.

Imperfective Aspect

The simplest, and imperfective aspect of a verb can be attained by the use of the verb "быть." By placing the correct form of "быть," in front of a Russian infinitive, you can create a verb in imperfective future tense.

Form будь is imperative of to be, but in this case it roughly means "will"

Can you decipher these?

 * Я буду играть.
 * Ты будешь говорить.

As an FYI, the imperfective aspect in Russian refers to a habitual action that we would not go out of our way to delineate. While "Я играю в игру" (I am playing the game) shows current action in a way not unlike English, "Я играла в игру" (I played-feminine the game) relates a habitual action to the playing of the game in the past. English leaves this ambiguous.

Perfective aspect For perfective aspect verbs, just use the table above for present tense endings, and you will get future tense (do you remember that perfective verbs have no present tense?) E.g. заиграть 'to begin playing' - я заиграю 'I shall begin to play'.

Prepositional case adjectives
Recall that the prepositional case is used when the object of a sentence is a location. Earlier you learned how to modify nouns (usually by adding е).

Russian adjectives must agree with their following noun in gender, number, and case.

With a masculine noun in the prepositional case, a preceding adjective usually ends in ом. The ending is ем for the 5-letter spelling rule, and for soft-ending (й or ь) adjectives.

With a feminine noun in the prepositional case, a preceding adjective usually ends in ой (pronounced "oy"). The ending is ей (pronounced ("yee") for the 5-letter spelling rule, and for soft-ending (й or ь) adjectives.

Prepositional case plural adjectives and nouns
With a plural noun in the prepositional case, a preceding adjective usually ends in ых (pronounced "eeh"). The ending is их (pronounced ("ih") for the 7-letter spelling rule, and for soft-ending (й or ь) adjectives.

Plural nouns in the prepositional case usually end in ах (pronounced "ach"). The ending is ях (pronounced ("yach") for soft-ending (й or ь) nouns.

Prepositional case personal pronouns
The personal pronouns change (considerably!) in the prepositional case.

Я ("I") becomes обо мне (pronounced "obo mnyeh").

Ты ("you" informal) becomes о тебе (pronounced "o tyehbyeh").

Он ("he") becomes о нём (pronounced "o nyom").

Она ("she") becomes о ней (pronounced "o nyee").

Мы ("we") becomes о нас (pronounced "o nas").

Вы ("you" formal) becomes о вас (pronounced "o vas").

Они ("they") becomes о них (pronounced "o neech").

Prepositional case possessive pronouns
If the object possessed is masculine or neuter, use the following possessive pronouns: моём ("my"), твоём ("your" informal), нашем ("our'), вашем ("your" formal), чьём ("whose?"), этом ("this").

If the object possessed is feminine, use the following possessive pronouns: моей ("my"), твоей ("your" informal), нашей ("our'), вашей ("your" formal), чьей ("whose?"), этой ("this").

If the objects possessed are plural, use the following possessive pronouns: моих ("my"), твоих ("your" informal), наших ("our'), ваших ("your" formal), чьих ("whose?"), этих ("this").

(Russian schools teach all that to second-graders! Now you understand why Ronald Reagan called the Soviet Union the "evil empire"!)

Prepositional case question words
Some question words change in the prepositional case. Что ("what," pronounced "shto") changes to о чём (pronounced "o chyom"). Кто ("who," pronounced "kto") changes to о ком.

Conjunctions: "and," "yes but," and "but"
Let's do something simpler.

И (pronounced "ee") means "and."

А (pronounced "ah") means "yes, but."

Но (pronounced "no") means "but."

Reflexive verbs
In English we add "self" to a pronoun to indicate reflexive action. E.g., "I wash myself" is different from "I wash my dog." In Russian, reflexive action is in the verb, not in the pronoun. E.g., a Russian would say something like "I washself."

This reflexive action is indicated by the suffix ся added to the verb, if the verb ends in a consonant. But if the verb ends in a vowel you instead add сь. Note that the former adds a syllable but the latter doesn't!

The verb учиться means "study" (pronounced "oo-cheet-syah"). The verb conjugates:

Three words for "study"
Russia has three words that translate to "study." (You can imagine that Russians must study three times harder than Americans to learn language skills!)

Учиться (pronounced "oo-cheet-syah") usually refers to where you go to school, e.g., "I go to Harvard University." As a memory aid, picture that Russians students cheat.

Изучать (pronounced "ee-zoo-chat") usually refers to the subject you study, e.g., "I study physics." As a memory aid, think that the zoo is where you study subjects such as monkeys, elephants, etc.

заниматься (pronounced "zan-ee-mat-syah") usually refers to doing homework, e.g., "I'm studying at the library." As a memory aid, think that your "zany mother makes you do your homework."

There is also a fourth verb, готовиться (perf. подготовиться), which means to prepare yourself, in this case to study for something, e.g. an exam. This is used with the preposition к + dative case. Например: Я готовлюсь к экзамену по русскому языку.

Two words for "also"
Russian has two words that translate to "also."

Тоже (pronounced "to-zheh") means that two people are doing the same thing (e.g., "I'm a student and my sister is also a student").

Также (pronounced "takzheh") means that one person does two different things (e.g., "I'm a student and I also work part-time").

As a memory aid, picture that Emperor Tojo of Japan is also the emperor of Russia. He has a reclusive brother Takzhye who only does things by himself.

Going by foot, by car, and going regularly
Russian has three words that translate to "going."

Идти (pronounced "eed-tee") means to go by foot. As a memory aid, think the conjugation он идёт ("he walks," pronounced "on eed-dyot") which sounds like "he's an idiot to walk (with the traffic so dangerous)."

ехать (pronounced "ee-hot") means to go by car, bus, etc. Note that conjugations are еду, едешь, едет, едем, едете, едут—none have the х!

ходить (pronounced "hod-deet") means to go back and forth habitually, e.g., "I go to school every day." As a memory aid, think of hod carriers going back and forth up and down ladders (a hod carrier carries morter to a bricklayer).

Necessity and freedom
"I have to" translates to я должен (pronounced "dol-zhen," sort of like "dolphin")—if the subject is masculine! If the subject is feminine, it's должна. If the subject is neuter, it's должно. If the subject is plural, it's должны.

Remember that "have to" is an adjective, not a verb! Don't try to conjugate it as a verb.

The opposite of "have to" is freedom. E.g., "I'm free this evening" means there's nothing you have to do. The adjectives are свободен (masculine, pronounced "sva-bod-den"), свободна (feminine, pronounced "sva-bod-na"), свободно (neuter, pronounced "sva-bod-no") and свободны (plural, pronounced "sva-bod-nih").

Note that вы ("you" formal, and "y'all") uses the plural forms, regardless of the gender of the person you're addressing.

Note that кто ("who") uses the masculine form, regardless of the gender of the person you're asking about

Lesson 4 >>

title: Russian/Lesson 3


text:
Talk:Indonesian/Lessons/This and that

Untitled
I think "These not are books" should be "These are not books"...

Zoro 12:32, 19 Mar 2004 (UTC)

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title: Talk:Indonesian/Lessons/This and that