NAT 5 - Waves and Radiation Powerpoint Answers

Transcription

1 NAT 5 - Waves and Radiation Powerpoint Answers 1. Light is a form of energy. 2. Angle of incidence = 60º. Angle of reflection = 60º. 3. Refraction is the change in the speed of light when moving from one medium to another. 4. P Refraction and Q Reflection. 5. Refraction ray diagram 6. Angle of incidence = X and angle of refraction = Z. 7. Cornea and the lens. 8. Short sight Concave lens and long sight Convex lens. 9. Short sight diagram.

2 10. Corrected short sight diagram. 11. The critical angle is the angle of light in a medium that will come out into air at 90º. 12. Critical angle = 37º. 13. An optical fibre is a long strand of flexible glass. 14. Optical fibre reflection diagram. 15. Frequency is defined as the number of waves that pass a point per second. 16. f = 20Hz.

3 17. Small amplitude and high frequency. Large amplitude and small frequency. 18. Speed of sound in descending order is Solids, Liquids and then Gases. 19. Speed of sound in air experiment. Speed of sound in air = Distance between mic A and mic B Time for sound to travel from mic A to mic B

4 20. Wall to the rear of the car = 0.34m. 21. Sound level meter decibels (db). 22. Range of human hearing - 20Hz to 20,000Hz. 23. Ultrasound involves frequencies greater than 20,000Hz. 24. Baby scan pictures. High frequency sound waves reflect off the baby tissue as echoes. These echoes are built up and turned into a computerised image. This image then shows the position and the movement of the baby. 25. Ear protectors absorb sound energy to protect a persons hearing. 26. Transverse waves The direction that a wave is travelling in is perpendicular to the dirction of the particles vibrating in the wave. Longitudinal waves The direction that a wave is travelling in is parallel or anti-parallel to the dirction of the particles vibrating in the wave. 27. P Transverse wave and Q Longitudinal wave.

5 28. Sound waves are longitudinal. 29. Transverse waves Gamma rays, X-rays, UV, Visible light,ir, microwaves, TV waves, radio waves and water waves. 30. EM spectrum waves all have a speed of 3x10 8 ms EM spectrum waves all have different frequencies and wavelengths. 32. Option 3 only is correct. 33. P X-rays, Q visible light, R microwaves. 34. λ = 0.05m. 35. f = 4.48x10 14 Hz. 36. a) Amplitude = 10m. b) Speed = 216ms -1. c) Wavelength = 27m. d) Frequency = 8Hz. 37. Period T = 4s. 38. The longer the wavelength the greater the diffraction.

6 39. Longer wavelength waves with diffraction. 40. a) Red light has a longer wavelength. b) Refraction of light in the prism. 41. a) X-rays, b) Infra-red. c) Gamma rays. d) Microwaves. 42. X Neutron, Y Proton and Z Electron. 43. Ionisation occurswhen an atom gains or loses an electron. 44. B 45. X Gamma rays and Y Gamma rays. 46. A Geiger-Muller tube is a radiation detector. 47. A radioactive tracer should have a short half-life and emit gamma rays.

7 48. a) To monitor their exposure to ionising radiation. b) Photographic film with windows of different materials placed on top of the film. c) The type of radiation and the quantity of radiation that they are exposed to. 49. Activity The number of atoms decaying/disintegrating per second. Activity is measured in Becquerels.(Bq) A = N/t. 50. A = 10Bq. 51. Absorbed Dose Radiation energy absorbed per kilogram of the absorbing tissue. Absorbed Dose is measured in Grays (Gy) or Joules per kilogram (Jkg -1 ). D = E/m. 52. D = 4Gy. 53. Equivalent Dose The biological harm caused by radiation on living tissue. Equivalent Dose is measured in Sieverts (Sv). H = DW R. 54. H = 1.2x10-3 Sv. 55. Option 3 is correct. 56. Half-Life The time taken for the activity of a radioactive source to half.

8 57. time = 140 years. 58. A = 4800Bq. 59. Half-life = 2 hours. 60. a) Radon gas in the atmosphere. b) Cosmic rays coming from the Sun and outer space. c) Rocks such as granite contain low levels of radioactive material. d) Workers in contact with radioactive materials in hospitals and nuclear power plants. 61. Options 1 and 3 are correct. 62. Options 1 and 3 are correct. 63. Neutrons must be released for the chain reaction to occur. 64. Advantages No greenhouse gases and a lot of energy can be created from a small mass of fuel. Disadvantages Nuclear waste is produced and the possible dangers of a nuclear accident which would cause mass devastation. 65. a) N = 1.2x10 11 decays. b) D = 0.2 µgy. c) H = 2x10-6 Sv.