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- 1. Key points<br />Formulae<br />Physics IGCSE Revision(Part 2)<br />Simple<br />Easy<br />By: Momina<br />
- 2. Sound Waves-Describing them<br />Amplitude<br />Wavelength<br />
- 3. Transverse Waves<br />The oscillations are at right angles to the direction of the wave.<br />For example light waves.<br />
- 4. Longitudinal Wave<br />( Rarefactions)<br />It consists of compressions and rarefactions.<br />Oscillations are in direction of travel.<br />For example: Sound waves.<br />
- 5. The Wave Equation<br />x<br />x<br />wavelength<br />Frequency<br />V <br />f<br />=<br />Speed <br />=<br />= Lambda<br />
- 6. Wave Effects: Reflection<br /> The waves are reflected from the surface at the same angle they hit it.<br />
- 7. Wave Effects: Refraction<br />Plastic<br /> Due to the plastic the water becomes shallower causing the waves to slow down. This effect is called refraction.<br />
- 8. Wave Effects: Diffraction<br />Diffraction is when the light bends around obstacles.<br />Wider gaps produce less defraction.<br />
- 9. Sound waves<br />Sound waves are caused by vibration<br />Sound waves consist of Longitudinal waves.<br /> - Compression passes Air pressure increases<br /> -Rarefaction passes Air pressure decreases<br />
- 10. Sound Waves<br />Sound waves need a medium to travel in. For instance the air.<br />Sound waves can also be diffracted due to their long wavelength.<br />They can be displayed on an oscilloscope. The sound enters via the microphone, a metal plate vibrates, these vibrations cause electrical oscillations producing a wave front.<br />IT IS NOT A PICTURE OF THE SOUND WAVE BECAUSE SOUND WAVES ARE NOT TRANSVERSE<br />
- 11. Speed of Sound<br />Temperature of air: Sound travels faster through hot air.<br />Does NOT depend on pressure: the pressure may change but the speed of the wave will remain the same<br />The speed of sound is different through different materials.<br />Ultrasound: sounds above the range of human hearing. <br />
- 12. How to Measure the speed of an echo?<br />To measure echo<br /> Take note here the distance is the distance from to the wall and then BACK !<br /> Distance<br />=<br />Speed <br />Time<br />You could use:<br /><ul><li>Echo-sounder
- 13. Electronic tape measure (Works like an echo-sounder)
- 14. Radar</li></li></ul><li>Features of Light<br />Form of radiation<br />Travels in straight lines<br />Transfers energy<br />Transverse waves<br />Can travel through vacuum<br />300,000 m/s<br />
- 15. Law of reflection<br />i˚=r˚<br />i, r and normal lie on the same plane.<br />
- 16. Total Internal Reflection<br />Anything greater than the critical angle does not have a refracted ray. Which means that all the light is reflected thus leading to TOTAL internal reflection.<br />
- 17. Lenses<br />Convex Lens<br />Concave Lens<br />Convex lenses are used in projectors as they form large, inverted, real images on the screen<br />
- 18. When the object is less than F1<br />Original Object<br />Refracted Object<br />Refracted image is <br /><ul><li>Upright
- 19. Larger
- 20. Virtual
- 21. It is also on the same side as F1</li></li></ul><li>When the object is at 2F1<br />Refracted image is <br /><ul><li>At 2F2
- 22. Inverted
- 23. The same size
- 24. Real</li></li></ul><li>When the Object is between F1 and 2F1<br />Refracted image is <br /><ul><li>Beyond 2F
- 25. Inverted
- 26. Larger
- 27. Real</li></li></ul><li>When the object is beyond 2F1<br />Refracted image is <br /><ul><li>Between F2 and 2F2
- 28. Inverted
- 29. Smaller
- 30. Real</li></li></ul><li>The Electromagnetic Spectrum<br />Electromagnetic waves are emitted when a charged particle oscillate or loose energy in some way.<br />
- 31. Electricity<br />Rubbing materials does not MAKE charge, it only separates charges that are already there.<br />Induced charge: this is the charge that ‘appear’ on an uncharged object because of the charged object nearby.<br />Charge is measured in Coulombs.<br />
- 32. Electricity*<br />Electrostatic precipitators: are fitted into chimneys in order to reduce pollution<br />
- 33. Electricity<br />When there are no ions in the air it is a good electrical insulator.<br />When there are ions present in the air it is a good conductor<br />Current is measured in amps.<br />
- 34. Current<br />Current remains the same at all points round a simple circuit.<br />x<br />Time<br />Current<br />Charge <br />=<br />Conventional Current flows from positive to negative.<br />Electron flow is from negative to positive.<br />
- 35. Potential Difference (Voltage)<br />The highest potential difference is when it is not in a circuit and it not supplying current. This is also known as the Electromotive force.<br />In a simple circuit, the sum of the PD’s across the components is equal to the PD across the battery. <br />
- 36. Resistance<br /> PD (Voltage)<br />V<br />=<br />=<br />Resistance<br />R<br />I<br />Current (A)<br />Ohms Law<br /> The current is proportional to the PD.<br />
- 37. How can resistance be increased?<br />1- Length : Doubling the length increases resistance<br />2- Cross-sectional area: halving the surface area. (thin wire is more resistance than a thick one)<br />3- Material<br />4- Temperature: resistance increases with temperature<br />
- 38. CIRCUIT WARS!<br /> Parallel Circuit<br /><ul><li>Gets full PD from the battery
- 39. One bulb removed the other still works
- 40. Total current = Sum of the currents in the branches.
- 41. Resistance:</li></ul>Simple Circuits<br /><ul><li>Bulbs share PD
- 42. One bulb removed, the other one goes out.
- 43. Current through each component is the same
- 44. Resistance:</li></li></ul><li>CIRCUIT WARS!<br /> Parallel Circuit<br />Simple Circuits<br />
- 45. Power<br /> Work done<br />=<br />Power<br />Time take<br />
- 46. Power<br />x<br />x<br />Voltage<br />V<br />I<br />P <br />Current<br />Power <br />=<br />=<br />
- 47. Power<br />x<br />x<br />2<br />Resistance<br />V<br />I<br />P <br />Current<br />Power <br />=<br />=<br />2<br />
- 48. Electrical Energy Equation<br />x<br />x<br />x<br />I<br />x<br />Current<br />Energy Transformed <br />=<br />=<br />E<br />t<br />PD<br />V<br />Time<br />
- 49. In Progress….<br />Part three of this series still remains a work in progress.. <br />Part 3 will contain:<br /><ul><li>Magnets and Currents
- 50. Electrons and Electronics
- 51. Atoms and Radioactivity</li>

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