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User talk:Sparo~enwikibooks

Your account will be renamed
Hello,

The developer team at Wikimedia is making some changes to how accounts work, as part of our on-going efforts to provide new and better tools for our users like cross-wiki notifications. These changes will mean you have the same account name everywhere. This will let us give you new features that will help you edit and discuss better, and allow more flexible user permissions for tools. One of the side-effects of this is that user accounts will now have to be unique across all 900 Wikimedia wikis. See the announcement for more information.

Unfortunately, your account clashes with another account also called Sparo. To make sure that both of you can use all Wikimedia projects in future, we have reserved the name Sparo~enwikibooks that only you will have. If you like it, you don't have to do anything. If you do not like it, you can pick out a different name.

Your account will still work as before, and you will be credited for all your edits made so far, but you will have to use the new account name when you log in.

Sorry for the inconvenience.

Yours, Keegan Peterzell Community Liaison, Wikimedia Foundation 23:46, 17 March 2015 (UTC)

Renamed
 This account has been renamed as part of single-user login finalisation. If you own this account you can |log in using your previous username and password for more information. If you do not like this account's new name, you can choose your own using this form after logging in: . -- Keegan (WMF) (talk) 05:31, 19 April 2015 (UTC)

title: User talk:Sparo~enwikibooks


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User:Lando5

Hello, and thanks for visiting my user page. You can find links to my user pages on other Wikimedia Foundation projects by visiting my Wikipedia user page.

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

title: User:Lando5


text:
User talk:Lando5

Thank you for visiting my talk page. If you need an immediate response to something please visit my Wikipedia talk page.

title: User talk:Lando5


text:
User:Neoptolemus/Language list

The following is a list of languages I hope to read and learn about in my spare time here on Wikibooks. This page is solely a reference for myself, so that I can reach the books more quickly. Νεοπτόλεμος 05:10, 5 January 2008 (UTC)

title: User:Neoptolemus/Language list


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Technical Theatre/Lighting/PAR/Lamps

Spot abbreviations

 * VNSP - Very Narrow Spot
 * NSP - Narrow Spot
 * MFL - Medium Flood
 * WFL - Wide Flood
 * EXG - Extra Wide Flood

title: Technical Theatre/Lighting/PAR/Lamps


text:
User:Srhat

About - Hakkında

 * 1) Introduction - Tanıtım
 * 2) About this book - Bu kitap hakkında
 * 3) Computing in Turkish - Türkçe bilgisayar
 * 4) Contributions to this Wikibook - Bu Vikikitap'a katkılar

Pronunciation and Alphabet - Alfabenin okunuşu

 * 1) A - I
 * 2) İ - R
 * 3) S - Z
 * 4) Vowel Classifications and Harmony
 * 5) Consonant Classifications and Harmony

Ways of enhancing your Turkish - Türkçenizi geliştirme yolları

 * 1) Turkish Satellite Television
 * 2) Turkish Music
 * 3) Turkish Movies
 * 4) Turkish on the internet
 * 5) Turkish newspapers & magazines

Lessons - Dersler

 * Unit One - Ünite Bir

 * 1) Lesson One - Greetings - Ders Bir -  Tanışma
 * 2) Lesson Two - I am... - Ders İki -  Ben...
 * 3) Lesson Three - Asking Questions - Ders Üç -  Soru Sorma
 * 4) Lesson Four - Are you busy today? - Ders Dört -  Bugün meşgul müsün?  Needs a lot of work. Give me some ideas, please!
 * 5) Unit One - Test - Ünite Bir - Test

 * Unit Two - Ünite İki

 * 1) Lesson Five - Asking for directions - Ders Beş - Yön Sorma
 * 2) Lesson Six -  Geography of Turkey and the Turkish Republic of Northern Cyprus - Ders Altı - Türkiye ve Kuzey Kıbrıs Türk Cumhuriyeti Coğrafyası[[Image:25%.png]]
 * 3) Lesson Seven - Transport - Ders Yedi -  Taşıma
 * 4) Lesson Eight - Services - Ders Sekiz -  Hizmetler
 * 5) Unit Two - Test - Ünite İki -  Test

 * Unit Three - Ünite Üç

 * 1) Lesson Nine -  Kinship - Ders Dokuz  -  Akrabalık
 * 2) Lesson Ten -  Kinship: Advanced - Ders On  -  Akrabalık:Gelişmiş

Grammar - Dil Bilgisi

 * 1) Word Order - Kelime Sırası
 * 2) Vowel Classifications and Harmony
 * 3) Pronouns - Adıllar
 * 4) Cases - Durumlar
 * 5) Plural - Çoğulluk
 * 6) Verbs - Eylemler
 * 7) Postpositions - İlgeçler
 * 8) Present Tense - Şimdiki Zaman
 * 9) Negative -  Present Continuous Tense - Olumsuz  -  Şimdiki Zaman
 * 10) Interrogative -  Present Continuous Tense - Soru  -  Şimdiki zaman
 * 11) Past Tense - Geçmiş Zaman
 * 12) Past Tense 2 - Geçmiş Zaman 2
 * 13) Negative Past Tense - Olumsuz Geçmiş Zaman
 * 14) Past Continuous Tense - Geniş Zaman
 * 15) Negative Past Continuous Tense - Olumsuz Geniş Zaman
 * 16) Future Tense - Gelecek Zaman

See tr:User:Srhat example All pages:
 * 1) Simple Present Tense (or Aorist Tense) - Geniş Zaman
 * 2) Turkish/Present Continuous Tense - Şimdiki Zaman
 * 3) Turkish/Future Tense - Gelecek Zaman
 * 4) Turkish/Seen Past Tense - Görülen Geçmiş Zaman
 * 5) Turkish/Heard Past Tense - Öğrenilen Geçmiş Zaman
 * 6) Turkish/Compound Tenses - Birleşik Zamanlar

If you're wondering what on Earth that just said, here's what it means: '''Hello! Welcome to your first lesson!''' Your first lesson will start with greetings, as they are what you will use in the beginning of conversations.

Greetings
Read the following dialogues. You can hover your mouse pointer over the parts of the dialogue, specific words or suffixes to see what they mean, but you don't have to understand every part of the word, each suffix from the first lesson. You will learn the rules later, so don't worry about them.

title: User:Srhat


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A-level Physics (Advancing Physics)/Stress, Strain & Young's Modulus

Stress
Stress is a measure of the internal force an object is experiencing per unit cross sectional area:

$$ \sigma = \frac{F}{A}$$

Where σ is stress (in Newtons per square metre or, equivalently, Pascals), F is force (in Newtons, commonly abbreviated N), and A is the cross sectional area of the sample.

This is identical to the formula for pressure. Two distinctions should be made between stress and pressure: Firstly, while pressure is typically used to describe fluids (liquids or gases), stress is used to describe solids. Secondly, while pressure can only act perpendicular to a surface, stress is also able to act parallel to a surface. Stresses acting parallel to a surface are known as shear stresses.

Tensile Strength
The (ultimate) tensile strength is the maximum tensile stress of a material can experience before breaking (and a change of cross-sectional area as a result) will occur.

Yield Stress
On a stress strain graph beyond the yield point (or elastic limit) the material will no longer return to its original length. This means it has become permanently deformed. Therefore the yield stress is the level of stress at which a material will deform permanently. This is also known as yield strength.

Strain
Stresses lead to strain (or deformation). Putting pressure on an object causes it to stretch. Strain is a measure of how much an object is being stretched. The formula for strain is:

$$\ \epsilon = \frac{\Delta l}{l_0} = \frac{l - l_0}{l_0} = \frac{l}{l_0} - 1$$,

where $$l_0$$ is the original length of a bar being stretched, and l is its length after it has been stretched. Δl is the extension of the bar, the difference between these two lengths.

Young's Modulus
Young's Modulus is a measure of the stiffness of a material, and describes how much strain a material will undergo (i.e. how much it will stretch) as a result of a given amount of stress. The Young's Modulus E of a material is calculated as:

$$E = \frac{\sigma}{\epsilon}$$

The values for stress and strain must be taken at as low a stress level as possible, provided a difference in the length of the sample can be measured. Strain has no units due to simply being the ratio between the extension and original length of a material, so Young's Modulus is measured by the same units as stress, i.e. newtons per square metre (Nm-2) or Pascals (Pa). As Young's Modulus is measured per unit area, it is an intensive property, meaning it only depends on the material being used, and not on the size of the material.

Stress-Strain Graphs

Stress (σ) can be graphed against strain (ε). The toughness of a material (i.e., how much it resists stress, in J m−3) is equal to the area under the curve, between the y-axis and the fracture point. Graphs such as the one on the right show how stress affects a material. This image shows the stress-strain graph for low-carbon steel. It has three main features:

Elastic Region
In this region (between the origin and point 2), the ratio of stress to strain (Young's modulus) is constant, meaning that the material is obeying Hooke's law, which states that a material is elastic (it will return to its original shape) if force is directly proportional to extension of the material

Hooke's Law
Hooke's law of elasticity is an approximation that states that the Force F (load) is in direct proportion with the extension (denoted by x or e) of a material, provided this load does not exceed the proportional limit. The constant k is inherent to the material being measured. Materials for which Hooke's law is a useful approximation are known as linear-elastic, or 'elastic materials'.

 * $$F = -kx\,$$

The relation is often denoted

 * $$F \propto x$$

The work done to stretch a wire or the Elastic Potential Energy is equal to the area of the triangle on a Tension/Extension graph, but can also be expressed as

 * $$\tfrac{1}{2}kx^2$$

Plastic Region
In this region (between points 2 and 3), the rate at which extension is increasing is going up, and the material has passed the elastic limit - it will no longer return to its original shape when the load is removed, and will now undergo plastic (permanent) deformation. After point 1, the amount of stress decreases due to necking at one point in the specimen. If the stress were recorded where the necking occurs we would observe an upward curve and an increase in stress due to this reduction in area(stress = Force / area, thus stress increases during necking). The material will now 'give' and extend more under less force.

Fracture Point
At point 3, the material has been fractured and so no further measurements can be taken.

Other Typical Graphs
In a brittle material, such as glass or ceramics, the stress-strain graph will have an extremely short elastic region, and then will fracture. There is no plastic region on the stress-strain graph of a brittle material.

Questions
/Worked Solutions/
 * 1) 100N of force are exerted on a wire with cross-sectional area 0.50mm2. How much stress is being exerted on the wire?
 * 2) Another wire has a tensile strength of 70MPa, and breaks under 100N of force. What is the cross-sectional area of the wire just before breaking?
 * 3) What is the strain on a Twix bar (original length 10 cm) if it is now 12 cm long?
 * 4) What is this strain, expressed as a percentage?
 * 5) 50N are applied to a wire with a radius of 1mm. The wire was 0.7m long, but is now 0.75m long. What is the Young's Modulus for the material the wire is made of?
 * 6) Glass, a brittle material, fractures at a strain of 0.004 and a stress of 240 MPa. Sketch the stress-strain graph for glass.
 * 7) (Extra nasty question which you won't ever get in an exam) What is the toughness of glass?
 * 8) Wire has a tensile strength of 0.95Mpa, and breaks under 25N of force. what is the cross-sectional area of the wire before and after breaking?
 * 9) Estimating the Young's Modulus of a diamond to be 900GPa, how many centimeters would a diamond cylinder stretch if it had a 2 millimeter diameter and a length of 10 kilometers?  Assume the force to be 10 Newtons. Also assume that the diamond does not break (it is currently unknown whether this would break the diamond and calculations on an object this bizarre should probably not be trusted anyway.)
 * 10) How many pounds is 10 Newtons? (This question is so nasty you should either skip it or just google the question! The "Worked Solutions" below is a botched attempt not worth repeating.)


text:
A-level Physics (Advancing Physics)/Stress, Strain & the Young Modulus/Worked Solutions

'''1. 10N of force are exerted on a wire with cross-sectional area 0.5mm2. How much stress is being exerted on the wire?'''

0.5mm2 = 0.5 x (10−3)2m2 = 0.5 x 10−6m2

$$\sigma = \frac{10N}{0.5 \times 10^{-6} m^{2}} = 20 \ 000 \ 000 \mbox{ Pa} = 20\mbox{ MPa}$$

'''2. Another wire has a tensile strength of 70MPa, and breaks under 100N of force. What is the cross-sectional area of the wire just before breaking?'''

$$70 \times 10^6 = \frac{100}{A}$$

$$A = \frac{100}{70 \times 10^6} \approx 1.43 \times 10^{-6}\mbox{ m}^2 = 1.43\mbox{ } \mu \mbox{m}^2$$

3. What is the strain on a Twix bar (original length 10 cm) if it is now 12 cm long?

$$E = \frac{12 - 10}{10} = \frac{2}{10} = 0.2$$

4. What is this strain, expressed as a percentage?

0.2 x 100 = 20%

'''5. 50N are applied to a wire with a radius of 1mm. The wire was 0.7m long, but is now 0.75m long. What is the Young's Modulus for the material the wire is made of?'''

$$Y = \frac{(\frac{50}{\pi \times (1 \times 10^-3)^2})}{(\frac{0.75 - 0.7}{0.7})} \approx \frac{16000000}{0.0714} \approx 224000000\mbox{ Pa} = 224\mbox{ MPa}$$

'''6. Glass, a brittle material, fractures at a strain of 0.004 and a stress of 240 MPa. Sketch the stress-strain graph for glass.'''

7. (Extra nasty question which you won't ever get in an exam) What is the toughness of glass?

Toughness equals the area under the above graph. Since glass is brittle, we can assume that the gradient of the graph is constant, and, since the graph passes through the origin, it is a triangle. So:

$$A_{triangle} = \frac{\mbox{base } \times \mbox{ height}}{2} = \mbox{ Toughness } = \frac{\mbox{strain } \times \mbox{ stress}}{2} = \frac{0.004 \times 240 \times 10^6}{2} = 480000 \mbox{ Jm}^{-3} = 480 \mbox{ kJm}^{-3}$$


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User talk:Jahang ajang

Welcome!
Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally.--Laleena (talk) 12:50, 5 January 2008 (UTC)

title: User talk:Jahang ajang


text: User talk:91.124.152.128

title: User talk:91.124.152.128


text:
A-level Physics (Advancing Physics)/Metals

There are several physical properties of metals you need to know about:

Electrical Properties
Metals on a microscopic scale consist of positive metal ions in 'sea' of free (delocalised) electrons. The electrons act are able to freely move around the metallic lattice, in and between the ions. Metallic bonding is therefore described as non-directional, in contrast to the directional bonds found between atoms in covalently-bonded materials (e.g. carbon atoms in diamond).

As the delocalised electrons each carry charge and are able to move freely, they are described as 'mobile charge carriers'. Electricity is simply the flow of charged particles, and so the presence of a high number of mobile charge carriers per unit volume in metals means they tend to be very effective conductors. In contrast, ionically-bonded materials involve ions in fixed positions. The ions are charged particles, however as they are immobile they are not described as mobile charge carriers, making ionic substances (eg sodium chloride) unable to carry electric current when solid.

When a current flows through a metal, the delocalised electrons collide with the metal ions, transferring kinetic energy to them, resulting in an increase in the temperature of the metal. As the temperature of the metal increases and its metal ions vibrate more, electrons are more likely to collide with them, meaning the flow of current is resisted. The resistance of a metal therefore increases with temperature.

Similarly, as higher currents involve a faster flow of electrons, they cause more collisions between electrons and metal ions, and so cause the conducting material to increase in temperature. This is exemplified by the UK power grid - electricity is transferred throughout the country at extremely high voltages (typically 275kV or 400kV) but low currents, therefore allowing the electricity to travel at a high power without significant heating occurring in the wires.

Mechanical Properties
This 'sea' of free electrons can also be described as a glue that does not dry. The negatively charged electrons have an electro-static attraction to the positively charged metal ions. This is what holds the entire metal structure together and gives metals their strength, i.e. the ability of the material to resist coming apart.

It also means that metals will change shape without coming apart completely (breaking). This is known as plastic deformation, which is when a material changes permanently (unlike elastic deformation) and also does not fracture (like when a glass fibre is stretched too far). Pure metals are usually incredibly ductile and malleable and can worked into a wide variety of shapes. The sea allows the atoms to move past each other. Atoms can move out of their place on the lattice. Other atoms can then go and fill that place. Entire layers of atoms in a crystal lattice can slip past one another, and the free electrons flowing between will keep them stuck together [see dislocations]. The glue allows movement of atoms without breaking the metallic bond, i.e. the electrostatic attraction between the free-flowing electrons and the positive ions.

Of course, metals do eventually fracture, however, they tend to show necking first.

This could not happen in a material where the strength comes from covalent bonds because the electrons need to be in specific positions. When ionic bonds or covalent bonds are broken, they do not generally go back together. Materials held together entirely by covalent or ionic bonds tend to be very brittle. The bonding in metals is not directional and not permanent. This gives metals their strength and plasticity, their most useful mechanical properties.

List of Mechanical Properties
Stiffness

As the electrostatic attraction between the sea of electrons and metal ions hold the layers quite strongly, metals resist deformation quite well. This is especially true with alloys, where atoms of different sizes prevent the layers slipping past each other.

Ductile

Since the bonding is non-directional and non-permanent, with electrons that are free to move around, atoms can move about and slide past each other. This makes metals relatively ductile.

Toughness

Metals are tough for the same reason as they are ductile: the positive ions can slide past each other while still remaining together. So, instead of breaking apart, they change shape, resulting in increased toughness. This effect is called plasticity. When a tough material breaks the ratio of 'energy used / new surface area created' is very large.

Elasticity

When a metal is stretched, it can return to its original shape because the sea of electrons which bonds the ions together can be stretched as well.

Brittle

The opposite of tough: a material is likely to crack or shatter upon impact or force. It will snap cleanly due to defects and cracks. Metals can be brittle in certain circumstances, and a metal can be made more brittle by alloying or by work hardening.

Malleability

Metals are malleable because their atoms are arranged in flat planes that can slide past each other. Their bonds are non-directional. Metals also contain dislocations which mean that ions in the structure can be moved unilaterally rather than as a whole layer, which takes less energy to do.

Thermal Properties
Metals conduct electricity well for 2 main reasons. Firstly, they are in a lattice. The atoms are arranged both closely and neatly. This means that atoms transmit forces very efficiently through the material, so thermal vibrations pass heat energy along easily. This effect is also observed in ionic lattices and in silicon and diamond which are covalent lattices.

Secondly, the free electrons move more when heated, which is another method of passing heat through the lattice.

Transformation
Diffusive transformation: occur when the planes of atoms in the material move past each other due to the stresses on the object. This transformation is permanent and cannot be recovered from due to energy being absorbed by the structure

Diffusionless transformation: occurs where the bonds between the atoms stretch, allowing the material to deform elastically. An example would be rubber or a shape memory metal/alloy (often referred to as SMA) such as a nickel-titanium alloy. In the shape memory alloy the transformation occurs via the change of phase of the internal structure from martensitic to deformed martensitic, which allows the SMA to have a high percentage strain (up to 8% for some SMA's in comparison to approximately 0.5% for steel). If the material is then heated above a certain temperature the deformed martensite will form austenite, which returns to twinned martensite after cooling.

Arrangement of atoms
Metal atoms form lattices. These are neat ordered rows of atoms that stack together to make layers, which in turn stack neatly to make a 3D structure. The fact metals stay in ordered structures is key to their properties. The neat ordered rows will stretch billions and billions of atoms across. However, they do not go on forever. Metals are usually formed from a molten state. When the liquid solidifies, this happens in many places at once. Therefore many crystals form at once, and the crystals are oriented randomly with respect to one another. Metals are polycrystalline.

How grains affect the mechanical properties is beyond the scope of the A-level course, however, as a rule of thumb, smaller grains mean a higher strength. Single crystal metals can be grown, and they have interesting unique properties related to their geometry. However, this is a difficult and specialised process, but single crystal metals can be used for turbine blades inside aeroplane engines.

Questions
1. Would you expect a metal to have more or less conductivity than a semiconductor? Why?

2. How can the stress-strain graph for a metal be explained in terms of ions in a sea of electrons?

3. As a metal heats up, what happens to its conductivity? Why?

/Worked Solutions/


text:
A-level Physics (Advancing Physics)/Metals/Worked Solutions

'''1. Would you expect a metal to have more or less conductivity than a semiconductor? Why?'''

A metal has more conductivity than a semiconductor because a metal has more ions than a semiconductor, and hence more free (delocalized) electrons.

2. How can the stress-strain graph for a metal be explained in terms of ions in a sea of electrons?

In the elastic region, the ions are held together by the charge between them and the electrons, and they can move apart when under stress. Then, once the ions are too far apart, the bonds aren't strong enough to pull them back together, so the metal entends under the stress. Eventually, the bonds cannot maintain the structural integrity of the metal any more, so the metal 'necks' in one place, and then the metal fractures.

'''3. As a metal heats up, what happens to its conductivity? Why?'''

As a metal heats up, both ions and electrons vibrate more. This means that the collision rate between ions and electrons goes up, so it is harder for electrons to travel through the metal. So, as a metal heats up, its conductivity goes down.


text:
A-level Physics (Advancing Physics)/Internal Resistance

Batteries, just like other components in an electric circuit, have a resistance. This resistance is known as internal resistance. This means that applying Ohm's law (V = IR) to circuits is more complex than simply feeding the correct values for V, I or R into the formula.

The existence of internal resistance is indicated by measuring the potential difference across a battery. This is always less than the EMF of the battery. This is because of the internal resistance of the battery. This idea gives us the following formula:

PD across battery = EMF of battery - voltage to be accounted for

Let us replace these values with letters to give the simpler formula:

Vexternal = E - Vinternal

Since V = IR:

Vexternal = E - IRinternal

You may also need to use the following formula to work out the external potential difference, if you are not given it:

Vexternal = IΣRexternal

You should also remember the effects of using resistors in both series and parallel circuits.

Questions
1. A 9V battery is short-circuited. The potential difference across the battery is found to be 8V, and the current is 5A. What is the internal resistance of the battery?

2. What is the EMF of the battery in the following circuit?

3. What is the internal resistance of the battery in the following circuit?

/Worked Solutions/


text:
Cookbook:Rhubarb Fool

| Dessert

Rhubarb fool is a traditional dessert in Swedish cuisine. Its sweet and sour taste makes it a perfect summer dessert, to be served after a heavy meal.

Ingredients

 * 500 g fresh or frozen rhubarb
 * 4 dl water
 * 1 dl white granulated sugar
 * 3 tbsp potato starch
 * Milk, or a mixture of milk and cream, for serving

Procedure

 * 1) Rinse the rhubarb and cut it into smaller pieces, about 1–3 cm in length. If the rhubarb is coarse or of low quality, it may be necessary to peel it first.
 * 2) Bring the water and sugar to a boil. Add the rhubarb and boil until soft, about 3–5 minutes. Meanwhile, mix the starch with a bit of water until it dissolves.
 * 3) When the rhubarb is soft, whisk or stir vigorously to make sure all the rhubarb pieces break up into strings. There should be no whole pieces left—if necessary boil some more.
 * 4) Remove the rhubarb from the heat. Add the dissolved starch to the rhubarb while stirring. Keep stirring and bring the rhubarb to a boil once again.
 * 5) Pour the rhubarb fool into serving bowls and sprinkle some sugar on top to prevent a skin from forming. Leave to cool off and then refrigerate.
 * 6) Serve at room temperature or chilled, with milk.

Notes, tips, and variations

 * Depending on the type of rhubarb and whether it is peeled or not, the color of the rhubarb fool can vary from pale yellow to clear red.
 * Cornstarch can substitute for the potato starch.
 * To reduce the amount of carbohydrates in the recipe, consider use an artificial sweetener instead of the sugar. If using artificial sweetener then add that ingredient late. Unlike sugar it does not need to be dissolved in hot water.

title: Cookbook:Rhubarb Fool


text:
A-level Physics (Advancing Physics)/Internal Resistance/Worked Solutions

'''1. A 9V battery is short-circuited. The potential difference across the battery is found to be 8V, and the current is 5A. What is the internal resistance of the battery?'''

8 = 9 - 5Rinternal

5Rinternal = 1

Rinternal = 0.2Ω

2. What is the EMF of the battery in the following circuit?

$$\sum R_{\mathrm{external}} = \left( \frac{1}{8 + 4} + \frac{1}{4} \right)^{-1} = \left( \frac{1}{3} \right)^{-1} = 3 \mbox{ }\Omega$$

Vexternal = 5 x 3 = 15 V

15 = E - (5 x 10)

E = 50 + 15 = 65 V

3. What is the internal resistance of the battery in the following circuit?

$$\sum R_{\mathrm{external}} = \left( \frac{1}{2 + 4} + \frac{1}{3 + 6 + 1} \right)^{-1} = \left( \frac{4}{15} \right)^{-1} = 3.75 \mbox{ }\Omega$$

Vexternal = 7.5 x 3.75 = 28.125

Which actually makes this question impossible because the current is too high for the resistance supplied to the circuit.


text:
More C++ Idioms/Making New Friends

= Making New Friends =

Intent
To simplify creation of friend functions for a class template.

Motivation
Friend functions are often used to provide some auxiliary additional interfaces for a class. For example, insertion (<<), extraction (>>) operators and overloaded arithmetic operators are often friends. Declaring friend functions of a class template is a little more complicated compared to declaring a friend function for a non-template class. There are four kinds of relationships between classes and their friends when templates are involved:

 * One-to-many: A non-template function may be a friend to all template class instantiations.
 * Many-to-one: All instantiations of a template function may be friends to a regular non-template class.
 * One-to-one: A template function instantiated with one set of template arguments may be a friend to one template class instantiated with the same set of template arguments. This is also the relationship between a regular non-template class and a regular non-template friend function.
 * Many-to-many: All instantiations of a template function may be a friend to all instantiations of the template class.

The one-to-one relationship is of interest here because setting that up in C++ requires additional syntax. An example follows.

The above example is no good for us because the inserter is not a template but it still uses a template argument (T). This is a problem since it’s not a member function. The operator<< must be a template so that distinct specialization for each T can be created.

Solution here is to declare a insertion operator template outside the class before friend declaration and adorn the friend declaration with <>. It indicates that a template declared earlier should be made friend.

A disadvantage of the above solution is that it is quite verbose.

Solution and Sample Code
Dan Saks suggested another approach to overcome the verbosity of the above solution. His solution is known as "Making New Friends" idiom. The idea is to define the friend function inside the class template as shown below.

Such a friend function is not a template, but the template acts as a factory for "making" new friends. A new non-template function is created for each specialization of Foo.

title: More C++ Idioms/Making New Friends


text:
Talk:Ethnomedicine/Home Remedies/Saline Nasal Wash

Is the link to the Dr. Hoffman site needed? I think at most it can be in a reference tag, not linked blatantly and disruptively in the body of the text. Besides, this is common information, so I don't know that it really needs attribution.

The first step says something about water coming out of the throat?! Should be the other nostril, shouldn't it? —The preceding unsigned comment was added by 85.218.27.187 (talk • contribs).

external site contradicts
The link to the external site says one should close off one nostril when expelling water from the nose while the wikipedia article says it is not to be done.

Also... the repeated use of the word isotonic regarding saline solution seems wrong. Probably isosmotic was intended.


text:
More C++ Idioms/Multi-statement Macro

= Multi-statement Macro =

Intent
To write a multi-statement (multi-line) macro.

Motivation
Sometimes it is useful to group two or more statements into a macro and call them like a function call. Usually, an inline function should be the first preference but things such as debug macros are almost invariably macros rather than function calls. Grouping multiple statements into one macro in a naive way could lead to compilation errors, which are not obvious at first look. For example,

would fail in an if statement if a semi-colon is appended at the end.

The above statement expands to

giving a compiler error. Therefore, people came up with a widely used idiom for multi-statement macros, which is based on a do-while loop.

Solution and Sample Code
Here is an example of the multi-statement macro idiom.

When the caller appends a semicolon, this expansion becomes a single statement regardless of the context. Optimizing compilers usually remove any dead tests, such as while(0). This idiom is not useful when macro is used as a parameter to a function call. Moreover, this idiom allows return statement.

Known Uses
ACE_NEW_RETURN, ACE_NEW_NORETURN macros in Adaptive Communication Environment (ACE).

title: More C++ Idioms/Multi-statement Macro


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User talk:12.215.186.235

Mattb112885 (talk to me) 18:59, 5 January 2008 (UTC)

title: User talk:12.215.186.235


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User talk:65.42.87.48

Νεοπτόλεμος 20:31, 5 January 2008 (UTC)

title: User talk:65.42.87.48


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User talk:Sherifmosaad

Welcome!
Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally.--Laleena (talk) 21:43, 5 January 2008 (UTC)

title: User talk:Sherifmosaad


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User talk:Yso3

Welcome!
Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally.--Laleena (talk) 21:43, 5 January 2008 (UTC)

title: User talk:Yso3


text: User talk:203.122.32.22

title: User talk:203.122.32.22


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User talk:80.139.232.235

Join Us!
--Laleena (talk) 21:46, 5 January 2008 (UTC)

title: User talk:80.139.232.235


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Talk:Non-Programmer's Tutorial for Python 2.6/Boolean Expressions

Boolean expressions is jargon.

Sometimes you want to compare two values, to find out if they are the same or different. The result of a comparison is true or false. Expressions which return true or false are called Boolean expressions.


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User talk:Brandue

Welcome!
Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally.--Laleena (talk) 00:52, 6 January 2008 (UTC)

title: User talk:Brandue


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User talk:Ilio Costalis

Welcome!
Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally.--Laleena (talk) 00:52, 6 January 2008 (UTC)

title: User talk:Ilio Costalis


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User talk:Sparklez 365

Welcome!
Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally.--Laleena (talk) 00:52, 6 January 2008 (UTC)

title: User talk:Sparklez 365


text: User talk:66.26.58.109

title: User talk:66.26.58.109


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User:AtholM

G'day
Welcome my page. You probably got here by accident. :)

AtholM is a contraction of my real name, Athol Mullen.

For more information about me, see my user page on the English language wikipedia.

I also contribute photographs to wikipedia commons, and have a gallery of images there.

title: User:AtholM


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User talk:AtholM

Come introduce yourself at the new users page. If you have any questions, you can ask there or contact me personally. – Mike.lifeguard  | talk 03:30, 6 January 2008 (UTC)

title: User talk:AtholM


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User talk:75.156.106.118

Mattb112885 (talk to me) 02:17, 6 January 2008 (UTC)

title: User talk:75.156.106.118


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User talk:Mike.lifeguard/Archive 10

VIN
I split material from Vehicle identification number into several modules - the history of the version from which all are derived exists at Vehicle Identification Numbers (VIN codes)/Overview; does the history need to be duplicated in all modules derived from that material? (generally this isn't needed for an article split on Wikipedia, but I'm not familiar with Wikibooks policy). Random832 (talk) 06:58, 22 December 2007 (UTC)
 * If I understand you correctly, then the current state of affairs is fine. As long as there is some indication in the edit history for each page that the content added came from some other page, then the history is intact. Hope that helps. – Mike.lifeguard  | talk 17:31, 22 December 2007 (UTC)

Double Redirect
Hello Mike, I'm new here and my first edit was to fix a double-redirect. The page (Javascript/List of Contributers) was not removed from the list (as has been the case on all other wikis with which I have had experience), but marked out. Is there some mistake I have made? Thanks for your help, Νεοπτόλεμος 18:37, 22 December 2007 (UTC)
 * Nope, that's how it's supposed to be. Good work. – Mike.lifeguard  | talk 23:53, 22 December 2007 (UTC)

Unsure
We have this & this which all instinct tells me should be one page? I got there from this which may be worth keeping an eye open for. Cheers -- Herby talk thyme 13:31, 23 December 2007 (UTC)
 * Thanks; will take care of this later – Mike.lifeguard  | talk 16:33, 23 December 2007 (UTC)
 * [[Image:Yes_check.svg|15px| ]]  – Mike.lifeguard  | talk 02:35, 25 December 2007 (UTC)

AWB
Hi Mike, I asked WKnight if there are tools available that could help an eventual cleanup of the uncategorized pages (since I did the categories). In his answer he pointed me to AWB saying that you were a regular user of that tool. Before I take a detailed look at the tool I have a couple of questions for you if you have a minute:
 * Are you effectively using that tool?
 * Does it work?
 * Do we need special permission to use it at wikibooks (there is at wikipedia)?
 * Do you think it could help in the uncategorized pages cleanup?

Reagrds, -- Jacques (talk) (email) 14:07, 23 December 2007 (UTC)
 * I'm not sure how useful it would be for categorizing uncategorized pages - pywikipediabot would be more useful (I also have that). That process obviously can't be fully-auto, since the program can't decide how to categorize pages, but it is fairly straightforward. I'm fairly busy over the holidays, but come January, I can invest some time into categorization if you like. If you want to do it, go for it. No programming required, but it's bit more involved to get up and running. If you do it yourself, just remember that unless you have a bot account, you can't go full-speed (you're of course welcome to ask for a bot flag on a secondary account). – Mike.lifeguard  | talk 16:30, 23 December 2007 (UTC)
 * Thanks for the answers. The idea is to try to do it myself to save you time. Tool looks good from the documentation. I'll try to install it and start one page at a time. If it works I will come back for further advice (bot account, etc.). -- Jacques (talk) (email) 18:49, 23 December 2007 (UTC)

Health issues for gardeners
Hi Mike. I want to work on some health and safety stuff for the garden book, including proper lifting, carpel tunnel, eye washing, etc. If I start (and/or transwiki) some material for it, could you look it over for me? -- SB_Johnny | PA! 14:10, 23 December 2007 (UTC)
 * Abolutely! I'm a tad busy for now, but come Jan, I'll be around with more time. – Mike.lifeguard  | talk 16:31, 23 December 2007 (UTC)

Quick dewikify
Do you still need this? As you can tell, I don't come on WP often and people rarely talk to me. -raylu 06:23, 29 December 2007 (UTC)
 * If you can do it, I think it'd be very useful. Thanks! – Mike.lifeguard  | talk 16:11, 29 December 2007 (UTC)
 * w:User:raylu/monobook.js There it is. My only concern is that it removes all blank lines following it. So if there is a wikify tag followed by intended blank lines, it will remove them. Not a big deal, I hope. I won't be using it for long, so you should probably mirror it somewhere. -raylu 07:47, 1 January 2008 (UTC)
 * Thanks! Copied, and will try to optimize later. – Mike.lifeguard  | talk 00:02, 4 January 2008 (UTC)

Aly4alo
I noticed you had welcomed this user. Just because you are relative to him, he has uploaded a non-tracable image. Could you please trace him with your tools, if possible? Laleena (talk) 01:43, 31 December 2007 (UTC)
 * CheckUser can't help in this case. I've deleted the unlicensed duplicates, and if no license info is provided for the remaining image after 1 week from the upload date, it'll be deleted as normal. Thanks for keeping an eye out. – Mike.lifeguard  | talk 00:05, 4 January 2008 (UTC)

Happy New Year!
Happy New Year! All the best for you and your family. Thanks for helping my integration into the project. Your support has allowed the .NET Development Foundation book to reach a first milestone with the integration of all the content into a more “textbook like” structure. -- Jacques (talk) (email) 19:43, 31 December 2007 (UTC)

Welcome back
A great 2008 to you. Recent Meta "activity" noted :) Regards -- Herby  talk thyme 08:27, 4 January 2008 (UTC)

Re:Warn.js
I'll see what I can do about the watchlist thing. The problem is that the code is part of a reusable library, so if i change the library it is going to affect all the rest of the scripts that rely on it (which is quite a lot at this point). If i set it to not watch the page, then scripts that I use on my talk page (for instance) will cause my talk page to be removed from my watchlist.

The likely solution will be for me to create an entirely new function with specifiable options (such as watch page, minor edit, etc) and then slowly transition all scripts over to use this new function. I'll get to work on it this evening when I get back home, and I'll let you know how it progresses. --Whiteknight (Page) (Talk) 18:02, 8 January 2008 (UTC)

 * Wrote a long thing, then realize I misread you. Yes, changing (or not) the watched status of a page would need to be a parameter, which isn't the case now. Thanks a ton. – Mike.lifeguard  | talk 18:05, 8 January 2008 (UTC)

 * Okay, i completely rewrote a few functions, and updated the library. The script now uses your default values for page watching and minor edits. These will be the same as what you have set in the preferences. So, if you have "watch pages I edit" or "watch pages I create" enabled in the preferences, that's what will happen with the script. Same with the minor edits thing ("mark all edits minor by default").
 * Do me a favor, I want to get some people to test this script out so that I know I didnt mess it up worse. Also, give me some feedback about whether you want me to change the default behavior (mark them all as minor by default, don't ever watch them by default, etc). --Whiteknight (Page) (Talk) 00:08, 9 January 2008 (UTC)
 * Excellent! There was one missing comma (literally) that I poked darklama to find and fix. I think it'd be best to never watch those edits; it's just a welcome/warn. If there's some special case (like you're expecting a reply to a vandal warning or whatever) then you can watch the page separately for those special cases. As well, those are definitely minor edits, so that should be on. Great work though. – Mike.lifeguard  | talk 03:27, 11 January 2008 (UTC)

An edit of yours
One of your edits was recently vandalized by 70.248.55.77 (actually a few minutes ago). I thougth you would be interested. (I reverted.). Thanks, Laleena (talk) 00:08, 9 January 2008 (UTC)

no problem
Np, sorry I forgot to patrol them before. Mattb112885 (talk to me) 23:01, 10 January 2008 (UTC)

Ancient History/China/Ancient History
All that page is, is a template and four links to pages that have been moved. The page itself isn't needed anymore. It was intended as a link to four periods in ancient China, but those periods are linked to from the main China page. Νεοπτόλεμος 01:54, 11 January 2008 (UTC)
 * Ahh; if the content is elsewhere, that changes things. Deleted. – Mike.lifeguard  | talk 02:01, 11 January 2008 (UTC)
 * Thanks! Νεοπτόλεμος 02:02, 11 January 2008 (UTC)

Stupid question
Why do the Bulletin Board topics appear on the Watchlist page? Just wondering, the bulletin board seems quite accessible. -- Jacques (talk) (email) 04:16, 11 January 2008 (UTC)
 * That's a coincidence for right now. Actually, the Bulletin Board is not watched by much of the community, I think. In the future, I hope to change it regularly, and it probably won't always be a re-hash of the BB. —The preceding unsigned comment was added by Mike.lifeguard (talk • contribs) 04:27, January 11, 2008.
 * Thanks for the answer. Jacques —The preceding unsigned comment was added by Jacques Bergeron (talk • contribs) 14:59, January 11, 2008.

Honors World History Study Guide
I have agreed to transwiki the study guide. —The preceding unsigned comment was added by Xz64 (talk • contribs) 04:38, January 11, 2008.
 * OK. Do you need help to do that? To which wiki is it being moved? – Mike.lifeguard  | talk 04:39, 11 January 2008 (UTC)
 * If you have any trouble with the move to Wikiversity, just let me know. I have contacts there ;) Once the content has moved, please put at the top of the pages. Thanks!  – Mike.lifeguard  | talk 15:40, 11 January 2008 (UTC)

Too tempting
Sorry - had to edit (?) - feel free to "rollback"! -- Herby talk thyme 19:15, 11 January 2008 (UTC)
 * More thinking - to revoke the rights there should be a minimum of two admin/'crats agree on wiki that removal was necessary? Can't see I would do/want to do that on my own (I'd block for disruptive editing but not revoke?).  Cheers -- Herby  talk thyme 19:27, 11 January 2008 (UTC)
 * Well, I don't like what I had very much, so feel free. For rollback abuse, I'd warn then revoke if they do it again. If it's not a big deal for +rollbacker then it's not for -rollbacker either. For that, I'd say any admin can revoke for misuse after a warning.
 * Patroller is a bit more tricky. I'd say that the granting admin can revoke with no other process. If someone else wants to revoke patroller then they need another admin to agree.
 * /me edits some more. – Mike.lifeguard  | talk 19:39, 11 January 2008 (UTC)
 * Yeah - basically I agree with you. I think I'd want someone else's opinion on any removal anyway (emergencies excepted obviously).  It would be good to get this off the ground, cheers -- Herby  talk thyme 13:41, 12 January 2008 (UTC)
 * And... thinking... inactivity... If someone had been inactive for say 6 months would you want them to still have patroller rights?  I'll think too -- Herby  talk thyme 13:50, 12 January 2008 (UTC)
 * I'm with you on inactivity - the shorter the better for me. I'd like to keep the +patroller pool small as well, to better supervise them. It's easier to see bad rollbacks than bad patrols, since the whole point is that once it's patrolled nobody needs to look at it. – Mike.lifeguard  | talk 17:07, 12 January 2008 (UTC)
 * Agree completely - however not everyone here shares my views on inactivity..:) I inclined to say anyone who has been active for a month or so is "eligible" but equally more than a handful here is unlikely (& PLEASE let us avoid the en wp bureaucracy/dramas!)  Cheers -- Herby  talk thyme 17:10, 12 January 2008 (UTC)

I was hoping the only policy would be "admin discretion, and they're responsible for their own rights changes" - I'm trying to keep this as minimalist as possible. I'm going to wait to see some more comments at the !vote before making more changes, I think. – Mike.lifeguard  | talk 17:15, 12 January 2008 (UTC)

Explanation of New Category
Hi, Mike.lifeguard! I've seen your name all over but have never chatted with you. Thanks for being a great admin. Anyway, I am a GA at Old Dominion Univ. in Virginia, and for the past couple years, our students have taken part in the creation of their own textbook Social and Cultural Foundations of American Education. Now, times have changed, so we've decided to create a new book--the one you found. When I categorized all the modules in the old book, User:SBJohnny told me that it would be ok for me to categorize every module with the book's title. If you'd like me to try something else this time, I'll be happy to, but I thought I'd better explain.

By the way, if you have any suggestions for me, I'd sure appreciate it! Thanks, and keep in touch if you have time.

Pete (talk) 23:12, 11 January 2008 (UTC)
 * Didn't notice the category matched the title - that's perfect. Normally when pages are created with no content I'll tag it with, but I recognized your username from that previous project. As long as those page aren't mistakes I'll go back and patrol them. Thanks for the note. If you need help, this is one place. – Mike.lifeguard  | talk 23:14, 11 January 2008 (UTC)

 * Ah, yep... Pete knows what he's doing, no worries Mike! -- SB_Johnny | PA! 02:03, 12 January 2008 (UTC)

WB:AUTOBLOCK
could you delete this? I made a better one - WB:AUTO. Thanks, --- Anonymous Dissident  Talk 08:26, 12 January 2008 (UTC)
 * Actually, deletion is prob not needed - what's the harm in it staying? Thanks anyway. --- Anonymous Dissident  Talk 08:27, 12 January 2008 (UTC)
 * Put both up as shortcuts - no problem having both. – Mike.lifeguard  | talk 17:08, 12 January 2008 (UTC)

Cover for New Book
Hi, I am working to find a nice cover photo for my new book from the Commons. As you probably remember, my ignorance caused me to misrepresent the license of an Asian Fan Dance photo last semester, and I wonder if you can remind me again about this policy. I would like to save a copy of a Commons image on my local machine, and then edit in text including the book's title and contributors. After this is done, I would like to upload the image to the Commons again and use it as the cover photo. What type of license should I attach to this modified version of the image? I surely appreciate your help. Wikibooks is a great community, and I definitely don't want to abuse it.

Pete (talk) 15:27, 12 January 2008 (UTC)
 * I'm not an expert, but I think it'll be the same license that the original image had. You might ask on commons:Commons:Help desk - folks at Commons deal only with images, so they really know their stuff. See commons:Commons:Licensing for an example(!) – Mike.lifeguard  | talk 17:04, 12 January 2008 (UTC)

Your note
I have that option enabled but it doesn't work any more (I don't see the tabs). I use Firefox, if that's helpful. Laleena (talk) 21:47, 12 January 2008 (UTC)
 * That's odd; it's working for me. The warn tab should appear on Contribs and user talk pages; the welcome tab should appear when editing a non-existing user talk page. Do you have javascript enabled? Try a hard-reset (in firefox: CRTL+SHIFT+R) and let me know if you still have problems. – Mike.lifeguard  | talk 21:49, 12 January 2008 (UTC)
 * The tabs still won't appear. They did before, and I enabled it, and I did as you suggested, but it won't work. Huh? Laleena (talk) 12:48, 13 January 2008 (UTC)
 * Huh? is right. If you have javascript enabled, and you're using a browser that's not ancient, it should work. I'm using firefox, and it works fine for me. Can you go to a page where the tabs should appear, and report whether you're getting warnings in Tools>Error Console? – Mike.lifeguard  | talk 16:20, 13 January 2008 (UTC)
 * Works now. Thanks! Laleena (talk) 17:43, 13 January 2008 (UTC)

Re:warn.js
I did a few tests this morning, and I have to admit that i'm not getting any errors on this script. Do me a favor and clear your cache, just to make sure that your browser is using the most recent version of the script. You say that you get the error, but that the script still posts messages? --Whiteknight (Page) (Talk) 15:00, 13 January 2008 (UTC)
 * Done and still getting it. It's an error after everything important has happened. The user gets warned/welcomed; this doesn't affect function, but it's strange. I wouldn't have noticed anything except that firebug tells me 1 error, and then the message & code I quoted before. I suppose no fix is really necessary. – Mike.lifeguard  | talk 16:17, 13 January 2008 (UTC)

Weird...
Hey Mike, could you figure out what's going on here? This page's TOC box links to Ancient History/Greece/Introduction, but sends you straight to editing the page. The TOC is also here, but sends you straight to the artcile. Νεοπτόλεμος 16:56, 13 January 2008 (UTC)
 * I'm not getting that; it sends me to the page each time. purge the page cache, then confirm it still happens? – Mike.lifeguard  | talk 17:06, 13 January 2008 (UTC)
 * Works now. That was strange. Thanks! Νεοπτόλεμος 17:07, 13 January 2008 (UTC)

Your note
I didn't realize, but never mind. Thanks! Laleena (talk) 17:59, 13 January 2008 (UTC)

title: User talk:Mike.lifeguard/Archive 10