OpenLLM-France/wikimedia huggingface dataset:
# A-level Physics (Advancing Physics)/Potential Dividers

A potential divider, or potentiometer, consists of a number of resistors, and a voltmeter. The voltage read by the voltmeter is determined by the ratio of the resistances on either side of the point at which one end of the voltmeter is connected.
To understand how a potential divider works, let us consider resistors in series. The resistances add up, so, in a circuit with two resistors:
$\Sigma R=R_{1}+R_{2}$
If we apply Ohm's law, remembering that the current is constant throughout a series circuit:
${\frac {\sum V}{I}}={\frac {V_{1}}{I}}+{\frac {V_{2}}{I}}$
Multiply by current (I):
$\Sigma V=V_{1}+V_{2}$
So, just as the resistances in series add up to the total resistance, the potential differences add up to the total potential difference. The ratios between the resistances are equal to the ratios between the potential differences. In other words, we can calculate the potential difference across a resistor using the formula:
$V_{resistor}=\sum V\times {\frac {R_{resistor}}{\sum R_{external}}}$
In many cases, you will be told to assume that the internal resistance of the power source is negligible, meaning that you can take the total potential difference as the EMF of the power source.
A potential divider may work by combining a variable resistor such as an LDR or thermistor with a constant resistor, as in the diagram below. As the resistance of the variable resistor changes, the ratio between the resistances changes, so the potential difference across any given resistor changes.
Alternatively, a potential divider may be made of many resistors. A 'wiper' may move across them, varying the number of resistors on either side of the wiper as it moves, as in the following diagram:

## Questions

1. A 12 kΩ resistor and a 20 kΩ resistor are connected to a 9V battery. A voltmeter is connected across the 12kΩ resistor. What is the reading on the voltmeter? (Assume negligible internal resistance.)
2. A potential divider consists of 100 5Ω resistors, with a wiper which moves on one resistor for every 3.6° a handle connected to it turns. The wiper is connected to a voltmeter, and the circuit is powered by a 120V power source with negligible internal resistance. What is the reading on the voltmeter when the handle turns 120°?
3. A 9V battery with internal resistance 0.8Ω is connected to 3 resistors with conductances of 3, 2 and 1 Siemens. A voltmeter is connected across the 3 and 2 Siemens resistors. An ammeter is placed in the circuit, between the battery and the first terminal of the voltmeter, and reads 2A. What is the reading on the voltmeter?
Worked Solutions
# A-level Physics (Advancing Physics)/Power

Power is a measure of how much potential energy is dissipated (i.e. converted into heat, light and other forms of energy) by a component or circuit in one second. This is due to a drop in the potential energy, and so the voltage, of charge. Power is measured in Watts (commonly abbreviated W), where 1 W is 1 Js$^{−1}$. It can be calculated by finding the product of the current flowing through a component / circuit and the potential difference across the component / circuit. This gives us the equation:
$P={\frac {E}{t}}=IV$
where P is the power dissipated (in W), E is the drop in potential energy (in Joules, J), t is the time taken (in s), I is the current (in A) and V is either potential difference or electromotive force (in V), depending on the component being measured.
Since power is the amount of energy changing form per. second, the amount of energy being given out each second will equal the power of the component giving out energy.
You should be able to substitute in values for I and V from other formulae (V=IR, Q=It) in order to relate power to resistance, conductance, charge and time, giving formulae like these:
$P=I^{2}R$
$P={\frac {V^{2}}{R}}$
$P={\frac {QV}{t}}$

## Questions

1. The potential difference across a 9 W light bulb is 240 V. How much current is flowing through the light bulb?
2. How much energy is dissipated by a 10 W component in 1 hour?
3. The potential difference across a top-notch kettle, which can hold up to 1 litre of water, is 240 V, and the current is 12.5 A. 4.2 kJ of energy is required to raise the temperature of 1 kg of water by 1 °C. Assuming 100% efficiency and that the temperature has to be raised 80 °C (20 °C to 100 °C), how long does it take to boil 1 litre of water?
4. How much energy is dissipated by a 100Ω resistor in 10 seconds if 2A of current are flowing?
5. The charge on an electron is -1.6 x 10$^{−19}$ C. How long does it take for a mole (6 x 10$^{23}$ particles) of electrons to flow through a 40 W light bulb on a 240 V circuit?
Worked Solutions
# A-level Physics (Advancing Physics)/Phasors

Consider the image on the right. It shows a wave travelling through a medium. The moving blue dot represents the displacement caused to the medium by the wave. It can be seen that, if we consider any one point in the medium, it goes through a repeating pattern, moving up and down, moving faster the nearer it is to the centre of the waveform. Its height is determined by the amplitude of the wave at that point in time. This is determined by a sine wave.
Phasors are a method of describing waves which show two things: the displacement caused to the medium, and the point in the repeating waveform which is being represented. They consist of a circle. An arrow moves round the circle anticlockwise as the wave pattern passes. For every wavelength that goes past, the arrow moves 360°, or 2π$^c$, starting from the right, as in trigonometry. The angle of the arrow from the right is known as the phase angle, and is usually denoted θ, and the radius of the circle is usually denoted a. The height of the point at the end of the arrow represents the displacement caused by the wave to the medium, and so the amplitude of the wave at that point in time. The time taken to rotate 360° is known as the periodic time, and is usually denoted T.
Phase difference is the difference between the angles (θ) of two phasors, which represent two waves. It is never more than 180°, as, since the phasor is moving in a circle, the angle between two lines touching the circumference will always be less than or equal to 180°. It can also be expressed in terms of λ, where λ is the total wavelength (effectively, 360°). You can use trigonometry to calculate the displacement from the angle, and vice-versa, provided you know the radius of the circle. The radius is equal to the maximum amplitude of the wave.
Phasors can be added up, just like vectors: tip-to-tail. So, for example, when two waves are superposed on each other, the phasors at each point in the reference material can be added up to give a new displacement. This explains both constructive and destructive interference as well. In destructive interference, the phasors for each wave are pointing in exactly opposite directions, and so add up to nothing at all. In constructive interference, the phasors are pointing in the same direction, so the total displacement is twice as much.

## Questions

1. A sine wave with wavelength 0.1m travels through a given point on the surface of the sea. A phasor arrow representing the effect of this wave on this point rotates 1000°. How many wavelengths have gone past in the time taken for the phasor to rotate this much?
2. A sine wave has a maximum amplitude of 500 nm. What is its amplitude when the phasor has rotated 60° from its start position?
3. Two waves have a phase difference of 45°. When the first wave is at its minimum amplitude of -0.3m, what is the total amplitude of the superposed waveforms?
Worked Solutions
# A-level Physics (Advancing Physics)/Power/Worked Solutions

1. The potential difference across a 9 W light bulb is 240 V. How much current is flowing through the light bulb?
9 = 240I
$I={\frac {9}{240}}=0.0375{\mbox{ A}}$
2. How much energy is dissipated by a 10 W component in 1 hour?
$10={\frac {E}{60^{2}}}$
E = 60$^2$ x 10 = 36000 J = 36 kJ
3. The potential difference across a top-notch kettle, which can hold up to 1 litre of water, is 240 V, and the current is 12.5 A. 4.2 kJ of energy is required to raise the temperature of 1 kg of water by 1C. Assuming 100% efficiency and the temperature has to be raised 80K (20C to 100C), how long does it take to boil 1 litre of water?
$12.5\times 240=3000={\frac {4.2\times 10^{3}\times 80}{t}}$
$t={\frac {4.2\times 10^{3}\times 80}{3000}}=112{\mbox{ s}}$
In practice it may take longer than this as energy will be lost heating the surrounding air, heating the materials used in the kettle and the water may be colder than 20C.
4. How much energy is dissipated by a 100Ω resistor in 10 seconds if 2A of current are flowing?
${\frac {E}{10}}=2^{2}\times 100=400$
E = 4000 J = 4 kJ
5. The charge on an electron is -1.6 x 10$^{−19}$ C. How long does it take for a mole (6 x 10$^{23}$ particles) of electrons to flow through a 40 W light bulb on a 240 V circuit?
Total charge = 1.6 x 10$^{−19}$ x 6 x 10$^{23}$ = 96000 C
$40={\frac {96000\times 240}{t}}={\frac {23040000}{t}}$
$t={\frac {23040000}{40}}=576000{\mbox{ s}}=9600{\mbox{ min}}=160{\mbox{ h}}=6{\mbox{ days }}16{\mbox{ hours}}$
# A-level Physics (Advancing Physics)/Potential Dividers/Worked Solutions

1. A 12 kΩ resistor and a 20 kΩ resistor are connected to a 9V battery. A voltmeter is connected across the 12 kΩ resistor. What is the reading on the voltmeter? (Assume negligible internal resistance.)
$V_{12k\Omega }=9\times {\frac {12}{12+20}}=3.375V$
2. A potential divider consists of 100 5Ω resistors, with a wiper which moves on one resistor for every 3.6° a handle connected to it turns. The wiper is connected to a voltmeter, and the circuit is powered by a 120V power source with negligible internal resistance. What is the reading on the voltmeter when the handle turns 120°?
First, work out the number (n) of resistors between the terminals of the voltmeter:
$n={\frac {120}{3.6}}=33.{\bar {3}}$
The handle, then, has not turned enough to reach the 34th resistor, so the voltmeter is connected just after the 33rd resistor.
$V=120\times {\frac {33\times 5}{100\times 5}}=39.6{\mbox{ V}}$
3. A 9V battery with internal resistance 0.8Ω is connected to 3 resistors with conductances of 3, 2 and 1 Siemens. A voltmeter is connected across the 3 and 2 Siemens resistors. An ammeter is placed in the circuit, between the battery and the first terminal of the voltmeter, and reads 2A. What is the reading on the voltmeter?
First, work out the resistances of the resistors:
$R={\frac {1}{G}}={\frac {1}{3}},{\frac {1}{2}},1{\mbox{ }}\Omega$
Then, work out the external potential difference (i.e. excluding the potential difference lost due to the battery's internal resistance):
V$_{external}$ = E - IR$_{internal}$ = 9 - (2 x 0.8) = 7.4V
$V_{3\Omega ,2\Omega }=7.4\times {\frac {{\frac {1}{3}}+{\frac {1}{2}}}{{\frac {1}{3}}+{\frac {1}{2}}+1}}\approx 3.36{\mbox{ V}}$
# Blender 3D: Noob to Pro/Modeling a Human Character - Preparations

Actually, this model is made without any background reference images but enough knowledge of human figure makes this possible. Modeling the human body or any model in that case requires knowledge of it beforehand. Even with the background image references, there are still some details (like the armpit) that is not easily visible or are difficult to comprehend with just simple orthogonal projections. It is advised to make some study on basic human figure and proportions first.
For those who likes to have a background reference image to use while modeling, use this orthogonal views of the model. You could still try and test your knowledge on the human figure later by trying to model one without image references.
# Blender 3D: Noob to Pro/Modeling with the Spin Tool

| previous module: "Modeling a picture" | • Table of Contents • Glossary | next module: "Spin Tool Introduction" |
The Spin tool is a great tool for modeling objects you might make on a lathe quickly and easily.
Lathe objects have circular cross sections along a certain axis. That is to say, when you cut such objects perpendicular to a certain axis you'll get circles. Examples of such objects includes rods, poles, wineglasses, and pails. A Blender render at the left shows some of these.
With the Spin tool you only have to "model" half the outline of your object. The object is completed after you spin this outline. A bit of cleanup here and there and your model is finished.
| previous module: "Modeling a picture" | • Table of Contents • Glossary | next module: "Spin Tool Introduction" |
# Blender 3D: Noob to Pro/Modeling tips

| previous module: "Modeling Realistically" | • Table of Contents • Glossary | next module: "Cheat the 3D" |
This is not really a tutorial, but a list of handy tricks you will probably use a lot when modeling.
1: Extrusion: To extrude, press E in edit mode with the vertices selected, move and click to place the extrusion. You'll basically need this for every model in blender, without it, most models would be really hard to create.
2: Set Smooth: Enabling smoothing on the face of a mesh will create a smooth gradient between it and the faces around it. To enable smooth shading on a face, select the faces you want to smooth and then go to Mesh → Shading → Smooth Faces.
3: Merge by Distance: Sometimes when editing, you might accidentally create duplicate geometry or have small holes in your model. To clean these up, select your entire model (or part of it) and then go to Mesh → Clean Up → Merge by Distance. The Merge Distance variable when performing this action determines the maximum distance between vertices for them to be merged.
4: Topology Flow: One of the most important things to keep in mind while modeling is the topology of the model. Topology is the arrangement and flow of the edges and faces that make up a mesh. Generally, you want to make your model with quads (faces with four edges) so that it is easy to perform actions such as loop cuts or ring selections. This isn't to say that triangles and faces with more than four edges shouldn't be used, but quads are preferable.
Example use of these techniques:
Topology Flow: https://web.archive.org/web/20210423191525/https://topologyguides.com/loop-reduction
If you want to add more handy techniques, please add them.
| previous module: "Modeling Realistically" | • Table of Contents • Glossary | next module: "Cheat the 3D" |
# Blocking the Figure

As with many models done in box modeling, let's start with a cube. The model is symmetrical so let's make use of it. Add a loop running vertically at the middle and delete the vertices on the left, leaving you with only half of the cube. Now add a mirror modifier.
* Initial box
Now add a loop running horizontally and fashion out the torso.
* Forming the torso
Add a vertical loop on the torso so that we will have more geometry to work on.
* Adding more geometry
Extrude the head and the legs. Add loops around the head and the bottom of the legs and extrude out the head and feet.
* Extrude head and legs
* The model at another view
Now add a loop around the torso and extrude out the arms. This is all for blocking
* Extruding out the arms
* From another view

# Detailing and Finishing

Add a loop that goes through the torso and the arms and another at the sides. This geometry will enable us to round and shape the figure.
* Adding more geometry and rounding the figure
Extrude out to form a rough hand. Add an extra loop around the hand and extrude out the thumb.
* Extruding the hand and thumb
Add more loops around the arm, thumb and hand. Work out this additional geometry to shape the parts.
* Shaping the hand
Add this loop to add more geometry on the legs and to the torso.
* Adding geometry
And then shape.
* Shaping
Add more loops on the leg and shape out the form.
* Forming the legs
Now time to shape the foot add more geometry and shape out the foot.
* Initial form of the foot
* Final form of the foot
Now take a look at your model. Adjust the form until satisfied. Work finished.
* Doing finishing touches
# Blender 3D: Noob to Pro/Modeling a Mug using Spinning and Extrusion

Start by deleting the default cube. In front view, Add a circle. Move the vertices around to form a backwards "L" shape. Select the vertex on the bottom left and go to Mesh-snap-cursor to selection. Then, in top view, select all the vertices and spin it 360 degrees. Then, select all verticies, hit wkey, and click remove doubles. Then, on one of the sides, select the middle face. Extrude it 0.7, and make an fgon with the three triangles on the side of the main part. Select the two squares on the top of the extrusion and extrude them to 1.82. then subdivide the inner part of the handle. Select the
middle edges and move them up. Extrude the faces above into the base. Position the camera and add a level three light source. Render the model. You can add color, texture, or anything else.
# Cherokee/Classification

Cherokee is an Iroquoian language, the sole extant member of the Southern Iroquoian branch. The Northern Iroquoian branch consists of the languages of the Six Nations of the Haudenosaunee, historically known by the exonym “Iroquois.” These consist of the Mohawk, Oneida, Onondaga, Cayuga, Seneca, and Tuscarora. Of the Iroquoian languages, Mohawk has the most speakers, at around 3,500. Cherokee has the second highest number of speakers, at around 2,000. The other Iroquoian languages are severely endangered, and Cherokee and Mohawk also unfortunately face a moribund trajectory unless revitalization efforts are successful.
Within Cherokee, there are two extant dialects, the North Carolina (Middle, or Kituwah) and Oklahoma (Overhill, or Western) dialects. There was historically a third dialect, the Lower dialect, spoken near the South Carolina-Georgia border, but it is now extinct.
# Cherokee/Consonants

The Cherokee language has 13 main consonants. Most sonorant consonants also have one (or in the case of [ʥ], two) devoiced form which occurs when adjacent to h.

### Stops

[ʔ], often used to separate adjacent vowel sounds; often used between the syllables in the English interjection “uh-oh”
[g] which is also aspirated to make [kʰ]; resembles the sounds used in the English “get” and “kit”
[gʷ], a labialized velar stop which is also devoiced as [kʷʰ]; for many speakers, especially in modern-day Oklahoma Cherokee, the articulation of this consonant is weakened and pronounced as [ɣʷ ~ w]. This consonant is usually pronounced like the sounds in the English words “iguana” and “question,” but sometimes is pronounced more closely to the sound in the English word “wear.”
[d], a voiced alveolar stop, can also be aspirated as the devoiced [tʰ]. This sound can be pronounced like the sounds in the English words “dam” and “taboo.”

### Nasals

[n] and its voiceless allophone [ʰn̥]; pronounced like the sound in the sound in the English word “no,” though there isn’t an English example of the devoiced form of this consonant.
[m], which is rarely used outside of loan words; pronounced like the sound in the English word “moon.”

### Fricatives

[h]; resembles the sound in the English word “hair”
[s], more commonly pronounced [ʂ ~ ʃ] in the Eastern dialect; pronounced like the sounds in the English words “silent” and “shook”

### Affricates

[ʥ], a voiced alveolo-palatal affricate, which has two voiceless equivalents in Oklahoma Cherokee: [ʨ] or a voiceless alveolar affricate [ʦ]. Occasionally, [ʥ] may be pronounced as [ʣ], a voiced alveolar affricate, though this is uncommon in Oklahoma Cherokee. This sound is more common in some communities in North Carolina Cherokee, along with the voiceless [ʦ]. However, in the Snowbird community, [ʥ] and [ʨ] are retained. These sounds are pronounced like those in the English words “jaguar,” “cheat,” “tsunami,” and “dead zone,” respectively.
[dɮ], a voiced lateral affricate, which may be devoiced as [tɬ], commonly pronounced simply as a lateral fricative [ɬ]. In the Eastern dialect, this consonant is merged with the alveolar affricate. There is no English equivalent to this sound, which is formed by pressing the tip of the tongue against the roof of one's mouth and letting air pass over the sides of the tongue, making a “slurpy” version of the sound one might hear in English words like “beetle.”

### Approximants

[l] with a voiceless allophone [l̥], often pronounced as a lateral fricative /ɬ/; an extinct dialect of Cherokee used an alveolar tap [ɾ] resembling the Spanish r. This sound pronounced like the sound in the English word “letter”
[w ~ ɰ] and devoiced as [ʍ]; pronounced like the sounds in the English word “wait” and “whip”
[j] and its devoiced equivalent [j̥ ~ ç]; pronounced like the sounds in the English word “you” and the interjection “hyah!”
# Cherokee/Accessibility

This site is dedicated to continuously monitoring and improving accessibility features so that everyone is able to learn the content with as few obstacles as possible. We welcome comments, concerns, or questions about accessibility on the Discussion page associated with this page.
Here are the people this website aims to be particularly accessible for in the medium term:
* dyslexics
* autists
* ADHDers
* colorblind people
# Cherokee/Body Parts

Description, Citation
Please help us elicit the missing information in this chart! BMA only tells us so much!
Cherokee Body Parts :
| Body Part | Normal Term | Set | INC Tonic Plural | Normally Unpossessed | Unpossessed Alternative | Method of Depossession |
| bone | khoóla | NA | (no) | yes | NA | NA |
| blood | giíga | NA | (no) | yes | NA | NA |
| meat, flesh | hawiiya | NA | (no) | yes | NA | NA |
| ear | qlẽni | A-ga | (no) | (no) | | |
| nose | hyvvsõli | A-ga | (no) | (no) | | |
| finger | :x́yesaqdṽqi | A-ga | yes | (no) | | |
| tooth | hndóhgṽqi | A-ga | yes | (no) | | |
| shoulder | nvvwõqi | A-ga | (no) | (no) | | |
| leg | nvv̀sgeéni | A-ga | (no) | (no) | | |
| backbone, spine | teèsgeéni | A-ga | (no) | (no) | | |
| thigh | áagalo | A-ga | (no) | (no) | | |
| butt | aagwali | A-ga | (no) | (no) | | |
| heel | :digẽna | A-ga | (no) | (no) | | |
| forehead | gvdegẽna | A | (no) | (no) | | |
| mouth | hõli | A | (no) | (no) | | |
| body | yelṽli | A | yes | (no) | | |
| cheek | qgwali | A | (no) | (no) | | |
| tongue | hngõqi | A-ga | (no) | (no) | GA hnga | |
| arm | hnoogẽni | A-ga | (no) | (no) | | |
| tooth | hndóhgṽqi | A-ga | yes | (no) | | |
| throat | hyvjẽni | A | (no) | (no) | | |
| hip | kasgẽni | A | (no) | (no) | | |
| eye | gahtõli | A | (no) | (no) | A gahta | mutation |
| head | skõli | A | (no) | (no) | B ska | setflip mutation |
| hand | oòyẽni | B | (no) | (no) | | |
| fingernail | asuhgahlṽqi | B | yes | (no) | | |
| skin | neegalṽqi | B | yes | (no) | GA neega | setflip mutation |
| lips | dee + ahanéégalv | B | ? | (no) | | |
| face | akátṽ | B | ? | (no) | | |
| foot | alahstééna | B | (no) | (no) | | |
| heart | adaahndo | B | (no) | (no) | | |
| navel | adiiyvvdi | B | (no) | (no) | | |
| chin | yuukálv | B | ? | (no) | | |
| hair | stigv | B | ? | (no) | | |
| hair (animal) | giihli | B | (no) | (no) | | |
| liver | eéla | B | (no) | (no) | | |
| butt | aksẽni | B | (no) | (no) | | |
| scar | hneelv́v́sṽqi | B | yes | (no) | oo ~ | oo |
| rib | nulaji | B | (no) | (no) | ga ~ | setflip |
# AVCE Information and Communication Technology/Programming
## Contents

* Program specification
* Program design
* Documentation
* Testing programs
* Standard ways of working
# A Beginner's Arduino Guide
## Table of Contents

Introduction
What is Arduino?
Where to get Arduino
Setting up Including software and materials.
Arduino Sketch
Arduino Language
First projects
* The Blink Lab Getting one LED to flash
* Reading input Reading an analog input
* Motor Speed - Using a digialWrite to change motor speed
Something a bit more complex
* Sensors
* Digital Display

## Read more

* General Engineering Introduction/Arduino and Motors