# data[].attributes.headline
Old Spec Wikibook for entire course - Still VERY Useful

# data[].attributes.subject
Old Spec Wikibook for entire course - Still VERY Useful

# data[].attributes.attachment_link.readable_text
Embed Size (px)

Transcript

<ul><li><p>PDF generated using the open source mwlib toolkit. See http://code.pediapress.com/ for more information.PDF generated at: Mon, 09 Jun 2014 17:01:22 UTC</p><p>A-level PhysicsOCR B (Advancing Physics)</p></li><li><p>ContentsArticlesAS 1</p><p>Optics 2Lenses 2Refraction 4</p><p>Communications 7Digital Storage 7Digital Processing 8Digitisation 11Signal Frequencies 13Bandwidth 17</p><p>Electricity 18Charge 18Current 19Voltage 20Power 21Resistance and Conductance 22Internal Resistance 24Potential Dividers 25Sensors 27Resistivity and Conductivity 29Semiconductors 30</p><p>Material Structure 31Stress, Strain &amp; the Young Modulus 31Metals 33Polymers 35</p><p>Waves 37What is a wave? 37Phasors 40Standing Waves 41</p></li><li><p>Young's Slits 43Diffraction 46Finding the Distance of a Remote Object 47</p><p>Quantum Physics 48Light 48Quantum Behaviour 50Electron Behaviour 53</p><p>Mechanics 55Vectors 55Graphs 58Kinematics 61Forces and Power 63</p><p>A2 65</p><p>Decay 66Exponential Relationships 66Capacitors 68Radioactive Decay 71Half-lives 72</p><p>Gravity 74Force 74Field 76Potential Energy 77Potential 78</p><p>Mechanics 80Simple Harmonic Motion 80Energy in Simple Harmonic Motion 83Damping 84Resonance 85Conservation of Momentum 87Forces and Impulse in Collisions 88Rockets, Hoses and Machine Guns 89Circular Motion 90</p><p>Astrophysics 92</p></li><li><p>Radar and Triangulation 92Large Units 94Orbits 95Doppler Effect 96The Big Bang 97</p><p>Thermodynamics 99Heat and Energy 99Specific Heat Capacity 100Ideal Gases 101Kinetic Theory 103Boltzmann Factor 104</p><p>Magnetic Fields 107Flux 107Induction 108Force 109Transformers 112Motors 113Generators 115</p><p>Electric Fields 117Force 117Field 118Potential 120Potential Energy 121</p><p>Particle Physics 123The Standard Model 123Quarks 125Bosons 126Leptons 128Millikan's Experiment 129Pair Production and Annihilation 130Particle Accelerators 131Cloud Chambers and Mass Spectrometers 132</p><p>Nuclear Physics 135Quantum Principles 135</p></li><li><p>Radioactive Emissions 136Energy Levels 137Fission 138Fusion 139Binding Energy 141Risks, Doses and Dose Equivalents 143</p><p>Appendices 145Trigonometry 145Logarithms 146Delta - 'difference in' 146Sigma - 'sum of' 147Derivation of Equations for Simple Harmonic Motion 147</p><p>Worked Solutions 149Lenses 149Refraction 150Digital Storage 151Digital Processing 152Digitisation 153Signal Frequencies 154Bandwidth 155Charge 156Current 156Voltage 157Power 157Resistance and Conductance 158Internal Resistance 159Potential Dividers 160Sensors 161Resistivity and Conductivity 163Semiconductors 164Stress, Strain &amp; the Young Modulus 164Metals 165Polymers 165What is a wave? 166Phasors 167Standing Waves 167</p></li><li><p>Young's Slits 168Diffraction 169Light 169Electron Behaviour 170Vectors 171Graphs 172Kinematics 175Forces and Power 176Exponential Relationships 176Capacitors 178Radioactive Decay 179Half-lives 180Gravitational Force 181Gravitational Field 182Gravitational Potential Energy 183Gravitational Potential 184Simple Harmonic Motion 185Energy in Simple Harmonic Motion 187Damping 188Conservation of Momentum 190Forces and Impulse in Collisions 192Rockets, Hoses and Machine Guns 193Circular Motion 194Radar and Triangulation 195Large Units 196Orbits 196Doppler Effect 197The Big Bang 198Heat and Energy 198Specific Heat Capacity 199Ideal Gases 199Kinetic Theory 200Boltzmann Factor 201Magnetic Flux 202Induction 203Magnetic Force 204Transformers 205Motors 206</p></li><li><p>Generators 206Electric Force 207Electric Field 208Electric Potential 209Electric Potential Energy 211The Standard Model 211Quarks 212Bosons 212Leptons 213Millikan's Experiment 214Pair Production and Annihilation 215Particle Accelerators 216Cloud Chambers and Mass Spectrometers 217Radioactive Emissions 218Energy Levels 219Fission 220Fusion 221Binding Energy 222Risks, Doses and Dose Equivalents 222</p><p>ReferencesArticle Sources and Contributors 224Image Sources, Licenses and Contributors 228</p><p>Article LicensesLicense 231</p></li><li><p>1</p><p>AS</p></li><li><p>2</p><p>Optics</p><p>Lenses</p><p>Curvature of WavefrontsLight can be viewed as beams travelling between points. However, from most light sources, the light radiatesoutwards as a series of wavefronts. Light from a light source is bent - wavefronts of light have a property known ascurvature.</p><p>Decreasing curvatures of wavefronts</p><p>As light travels further away from its source, its curvaturedecreases. Consider a sphere expanding gradually from a point,which represents a given wavefront of light. As the sphereexpands, the curvature of its surface decreases when we look atany part of the surface with a constant area. It should be noted atthis point that light from a source infinitely far away has 0curvature - it is straight. This is useful, as ambient light (light froma source that is far away) can be assumed to have a curvature of 0,as the difference between this and its actual curvature is negligible.The curvature of a wavefront is given as:</p><p>,</p><p>where v is the distance from the wavefront to the in-focus image depicted by the light. Curvature is measured indioptres (D).</p><p>Power of lenses</p><p>Calculating the power of a lens</p><p>The function of a lens is to increase or decrease the curvature of awavefront. Lenses have a 'power'. This is the curvature which thelens adds to the wavefront. Power is measured in dioptres, and isgiven by the formula:</p><p>,</p><p>where f equals the focal length of the lens. This is the distancebetween the lens and the point where an image will be in focus, ifthe wavefronts entering the other side of the lens are parallel.</p><p>http://en.wikibooks.org/w/index.php?title=File%3AWavefronts_circle.svghttp://en.wikibooks.org/w/index.php?title=File%3ALens_power.svg</p></li><li><p>Lenses 3</p><p>The Lens Equation</p><p>The lens equation, applied to a single pixel.</p><p>Overall, then, the formula relating the curvature of the wavefrontsleaving a lens to the curvature of the wavefronts entering it is:</p><p>where v is the distance between the lens (its centre) and thein-focus image formed, u is the distance between the lens (itscentre) and the object which the in-focus image is of, and f is thefocal length of the lens. The power of the lens can be substituted infor the reciprocal of f, as they are the same thing.</p><p>The Cartesian ConventionIf we were to place a diagram of the lens on a grid, labelled with cartesian co-ordinates, we would discover thatmeasuring the distance of the object distance is negative, in comparison to the image distance. As a result, the valuefor u must always be negative. This is known as the Cartesian convention.This means that, if light enters the lens with a positive curvature, it will leave with a negative curvature unless thelens is powerful enough to make the light leave with a positive curvature.</p><p>Types of Lens</p><p>Types of lens</p><p>There are two types of lens:Converging lenses add curvature to the wavefronts, causing themto converge more. These have a positive power, and have a curvedsurface which is wider in the middle than at the rim.</p><p>Diverging lenses remove curvature from the wavefronts, causingthem to diverge more. These have a negative power, and have acurved surface with a dip in the middle.</p><p>MagnificationMagnification is a measure of how much an image has been enlarged by a lens. It is given by the formula:</p><p>where h1 and h2 are the heights of the image (or object) before and after being magnified, respectively. If an image isshrunk by a lens, the magnification is between 0 and 1.Magnification can also be given as:</p><p>where v and u are the image and object distances. Therefore:</p><p>http://en.wikibooks.org/w/index.php?title=File%3ALens_equation.svghttp://en.wikibooks.org/w/index.php?title=File%3ALens_types.svg</p></li><li><p>Lenses 4</p><p>An easy way to remember this in the middle of a exam is the formula:</p><p>where I is image size, A is actual size of the object M is the magnification factor.</p><p>Questions1. A lens has a focal length of 10cm. What is its power, in dioptres?2. Light reflected off a cactus 1.5m from a 20D lens forms an image. How many metres is it from the other side ofthe lens?3. A lens in an RGB projector causes an image to focus on a large screen. What sort of lens is it? Is its powerpositive or negative?4. What is the focal length of a 100D lens?5. The film in a camera is 5mm from a lens when automatically focussed on someone's face, 10m from the camera.What is the power of the lens?6. The light from a candle is enlarged by a factor of 0.5 by a lens, and produces an image of a candle, 0.05m high, ona wall. What is the height of the candle?Worked Solutions</p><p>Refraction</p><p>Reflection</p><p>Angles of reflection and incidence</p><p>Reflection is when light 'bounces' off a material which is differentto the one in which it is travelling. You may remember fromGCSE (or equivalent) level that we can calculate the direction thelight will take if we consider a line known as the 'normal'. Thenormal is perpendicular to the boundary between the twomaterials, at the point at which the light is reflected. The anglebetween the normal and the ray of light is known as the angle ofreflection (r). The ray of light will be reflected back at the sameangle as it arrived at the normal, on the other side of the normal.</p><p>http://en.wikibooks.org/w/index.php?title=A-level_Physics_%28Advancing_Physics%29/Lenses/Worked_Solutionshttp://en.wikibooks.org/w/index.php?title=File%3AReflection_refraction_angles.svg</p></li><li><p>Refraction 5</p><p>RefractionRefraction is when light changes velocity when it travels across the boundary between two materials. This causes itto change direction. The angle between the normal and the refracted ray of light is known as the angle of refraction(r).</p><p>The Refractive IndexThe refractive index is a measure of how much light will be refracted on the boundary between a material and a'reference material'. This reference material is usually either air or a vacuum. It is given by the following formula:</p><p>where c0 is the speed of light in a vacuum (3 x 108 m/s) and c1 is the speed of light in the material.</p><p>Snell's LawWe can relate the refractive index to the angles of incidence (i) and refraction (r) using the following formula, knownas Snell's Law:</p><p>Total Internal ReflectionNormally, when light passes through a non-opaque material, it is both reflected and refracted. However, sometimes,rays of light are totally internally reflected; in other words, they are not refracted, so no light goes outside thematerial. This is useful in optic fibres, which allow a signal to be transmitted long distances at the speed of lightbecause the light is totally internally reflected.</p><p>Critical AngleThe critical angle is the minimum angle of incidence, for a given material, at which rays of light are totally internallyreflected. At the critical angle (C), the angle of refraction is 90, as any smaller angle of incidence will result inrefraction. Therefore:</p><p>Since sin 90 = 1:</p><p>In word form, in a material with refractive index n, light will be totally internally reflected at angles greater than theinverse sine of the reciprocal of the refractive index.</p></li><li><p>Refraction 6</p><p>Questions1. A ray of light is reflected from a mirror. Its angle to the normal when it reaches the mirror is 70. What is its angleof reflection?2. The speed of light in diamond is 1.24 x 108 m/s. What is its refractive index?3. The refractive index of ice is 1.31. What is the speed of light in ice?4. A ray of light passes the boundary between air and a transparent material. The angle of refraction is 20, and theangle of incidence is 10. What is the speed of light in this material? Why is it impossible for this material to exist?5. What is the critical angle of a beam of light leaving a transparent material with a refractive index of 2?Worked Solutions</p><p>http://en.wikibooks.org/w/index.php?title=A-level_Physics_%28Advancing_Physics%29/Refraction/Worked_Solutions</p></li><li><p>7</p><p>Communications</p><p>Digital Storage</p><p>Digital DataThere are two different types of data: analogue and digital. Analogue data can, potentially, take on any value.Examples include a page of handwritten text, a cassette, or a painting. Digital data can only take on a set range ofvalues. This enables it to be processed by a computer. Examples include all files stored on computers, CDs, DVDs,etc.</p><p>Pixels</p><p>Enlarged image of a computer, showing individualpixels.</p><p>Digital images are made up of pixels. A pixel represents the valueof an individual square of the image, and it has a value assigned toit. The total number of pixels in an image is just like the formulafor the area of a rectangle: number of pixels across multiplied bynumber of pixels down. When representing text, each pixel is acomponent of one character (for example, a letter, a number, aspace, or a new line), it is not the entirety of a character. Forinstance if the letter 'E' was to be taken as an example and asection was to be taken through the three protrusions; a minimumof seven (7) pixels would be used, one white pixel at the top, then one black (for the first protrusion), then one whitefor the gap, then a black one for the centre - and so on. A type face - such as Helvetica, or Times New Roman,maybe made up of a more complex pattern of pixels to allow for serif details.</p><p>BitsEach pixel's value is digital: it takes on a definite value. In a higher quality image, each pixel can take on a greatervariety of values. Each pixel's value is encoded as a number of bits. A bit is a datum with a value of either 0 or 1.The more values a pixel can take on, the more bits must be used to represent its value. The number of values (N) thata pixel represented by I bits can take on is given by the formula:N = 2I</p><p>Hence:</p><p>Log base 10 used here. For ratios, the base of the log does not matter, now we have</p><p>evaluated log 2 using base 10 log N must be base 10 as well.A pixel may be represented by values for red, green and blue, in which case each colour channel will have to beencoded separately. When dealing with text, the number of values is equal to the number of possible characters.Overall, for an image:Amount of information in an image (bits) = number of pixels x bits per pixel.</p><p>http://en.wikibooks.org/w/index.php?title=File%3APixel-example.png</p></li><li><p>Digital Storage 8</p><p>BytesA byte is equal to 8 bits. The major difference between bytes and SI units is that when prefixes (such as kilo-, mega-,etc.) are attached, we do not multiply by 103 as the prefix increases. Instead, we multiply by 1024. So, 1 kilobyte =1024 bytes, 1 megabyte = 10242 bytes, 1 gigabyte = 10243 bytes, and 1 terabyte = 10244 bytes.</p><p>Questions1. An image transmitted down a SVGA video cable is 800 pixels wide, and 600 pixels high. How many pixels arethere in the image?2. A grayscale image is encoded using 3 bits. How many possible values can each pixel have?3. The characters in a text document are numbered from 0 - 255. How many bits should each character be encodedwith?4. A page contains 30 lines of text, with an average of 15 characters on each line. Each character is represented by 4bits. How many megabytes of uncompressed storage will a book consisting of 650 pages like this fill on a computer'shard disk?5. A 10cm wide square image is scanned into a computer. Each pixel is encoded using 3 channels (red, green andblue), and each channel can take on 256 possible values. One pixel is 0.01 mm wide. How much information do...</p></li></ul>

# data[].attributes.attachment_link.keywords[]
download a-level physics - wikispaces physics.pdf a-level physics ocr b (advancing physics) contents ...

# data[].attributes.attachment_link.title
A-level Physics - Wikispaces Physics.pdf A-level Physics OCR B (Advancing Physics) Contents ...

# data[].attributes.attachment_link.description
Embed Size (px) Transcript PDF generated using the open source mwlib toolkit. See http://code.pediapress.com/ for more information.PDF generated at: Mon, 09 Jun 2014 17:01:22 UTC A-level PhysicsOCR B (Advancing Physics) ContentsArticlesAS 1 Optics 2Lenses 2Refraction 4 Communications 7Digital Storage 7Digital Processing 8Digitisation 11Signal Frequencies 13Bandwidth 17 Electricity 18Charge 18Current 19Voltage 20Power 21Resistance and Conductance 22Internal Resistance 24Potential Dividers 25Sensors 27Resistivity and Conductivity 29Semiconductors 30 Material Structure 31Stress, Strain & the Young Modulus 31Metals 33Polymers 35 Waves 37What is a wave?