Physics 2

Physics 2

1. The most efficient solar collectors track the position of the Sun.

2. A photocell transfers light energy into electrical energy.

3. Photocells produce Direct Current (DC) electricity as the electrons go in one direction.

4. The more intense the light on a photocell, the larger the voltage produced.

5. The larger the area of the photocell, the larger the voltage produced.

6. Wind is caused by convection currents.

7. You need a magnet, a coil of wire and movement to generate electricity.

8. Generating electricity is called the dynamo effect.

9. You can make more electricity by increasing the number of coils, the strength of the magnet or the speed of the movement.

10. Light has a shorter wavelength than infrared.

11. Hot objects emit infrared radiation.

12. Glass, and the greenhouse gases, let light through.

13. Glass, and the greenhouse gases, don’t let infrared through.

14. As the number of greenhouse gases increases, less infrared can get out and so the Earth warms up.

15. The greenhouse gases are carbon dioxide, water vapour and methane.

16. Natural sources of carbon dioxide include: respiration, forest fires and volcanic eruptions.

17. Man-made sources of carbon dioxide include: burning of fossil fuels, deforestation; waste incineration and cement manufacture

18. Natural sources of methane include: when organic material decays.

19. Man-made sources of methane include: the mining and burning of fossil fuels, farmed animals like cattle and rice paddies.

20. Fuels release heat energy

21. Water vapour mainly occurs naturally.

22. Power stations use the following fuels: fossil fuels (coal, oil, gas), biomass (wood, straw, manure), nuclear fuel (uranium or plutonium).

23. Power in measured in Watts (W)

24. The kilowatt hour (kWh) is a unit of electrical energy supplied

25. Step-up transformers increase the voltage

26. Step-down transformers decrease the voltage

27. The national grid uses step-up transformers to increase voltages as this decreases the current and therefore the energy lost through heating the power lines.

28. Step-down transformers are used to decrease the voltage to a safer 230V for use in our homes.

29. Radioactive substances give out nuclear radiation.

30. Alpha (α), Beta (β) and Gamma (γ) are the 3 types of nuclear radiation.

31. Background radiation is caused by rocks, medical uses, cosmic rays, building materials, food.

32. Ionising means the removal or addition of electrons to make positive or negatively charged particles.

33. Nuclear radiation can ionise atoms, which can cause body cells to mutate.

34. Nuclear waste can be disposed of by burying in landfill, burying underground in glass containers, or by reprocessing.

35. The planets in order are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto (dwarf planet)

36. The planets orbit the Sun as gravity pulls the planets towards the Sun.

37. The force towards the centre of a circle is called the Centripetal force.

38. A light year is the distance light would travel in year.

39. Unmanned space probes are useful as they do not need food, oxygen or water.

40. An asteroid is a rock which orbits the Sun.

41. The Moon is a natural satellite of Earth

42. Comets are balls of ice and dust.

43. Comets have highly elliptical orbits and come from outside of Pluto’s orbit.

44. Closest to a star a comet has a stronger gravitational pull, so it speeds up.

45. A NEO is a Near Earth Object (asteroid or comet) which may collide with Earth.

46. We use telescopes and satellites to monitor NEOs.

47. If a NEO is approaching we can launch a rocket containing explosives to break the NEO up.

48. The Big Bang theory states that the universe started by a massive explosion

49. Evidence for the Big Bang includes cosmic microwave radiation and red shift of galaxies.

50. Red shift of galaxies show they are moving away from us.

51. The further away a galaxy is, the faster it is moving away from us.

52. The most stable part of a star’s life is called the main sequence.

53. The most stable part of a star’s life is called the main sequence.

54. Red giants are red because they are cooler.

55. Thermonuclear fusion happens in a star, where hydrogen burns to make helium.

56. When supermassive stars die, they become black holes.

57. Black holes have such a strong gravitational pull that nothing can escape out again, including light.