12. Which of these answers correctly describes the action of control rods and moderator in a nuclear power station?
Moderator
Control rods
A.
absorb neutrons
slow down neutrons
B.
act as a coolant
absorb neutrons
C.
slow down neutrons
absorb neutrons
D.
absorb neutrons
act as a coolant
13. The emissivity of a planet surface is defined as ...
  • A. the ratio of the power of reflected radiation to the incident radiation
  • B. the ratio of the power of absorbed radiation to the incident radiation
  • C. the ratio of the power of radiation emitted that is reabsorbed by the atmosphere
  • D. the ratio of the power of radiation emitted to that radiated by a black body
14. Which of the following substances is likely to have a high albedo?
  • A. ice
  • B. water
  • C. sand
  • D. concrete
15. The Earth presents a circular cross-section to the Sun, recieving radiation of intensity S all year, where S is the solar constant. However this radiation is spread over the entire sphere of the Earth's surface.

This means the global average annual intensity on the upper atmosphere is:

  • A. S/8
  • B. S/4
  • C. S/2
  • D. S (no reduction)

16. Black body radiation is the name given to radiation emitted by a hot body. The graph below shows the distibution of radiation emitted.

black body radiation curve graph

If the temperature of a body is doubled, how does this affect the total power output and the peak wavelength?
Peak wavelength
Total power radiated
A.
increases
doubled
B.
increases
16 times higher
C.
decreases
doubled
D.
decreases
16 times higher

17. These 2 planets are radiating energy. Both have the same emissivity and have no atmosphere.

 

Planet X has a surface temperature of 200 K and has 16 times the surface are of Y. If both planets radiate the same power into space, planet Y must have a surface temperature of ...

  • A. 12.5 K
  • B. 400 K
  • C. 1600 K
  • D. 3200 K
18. Which one of these is not a major atmospheric greenhouse gas?
  • A. Carbon dioxide
  • B. Water vapour
  • C. Nitrogen
  • D. Methane

19. Which of these statements best describes the absorption of radiation by a greenhouse gas?

  • A. it absorbs a wide spectrum of infra-red radiation
  • B. it only absorbs narrow bands of infra- red radiation
  • C. it absorbs a wide spectrum of visible light radiation
  • D. it only absorbs narrow bands of visible light radiation

20. Greenhouse gases in the Earth's atmoshere will have several effects on the Earth. As the greenhouse effect increases, what will be the effect on the average global temperature and the mean power radiated into space?

  Avergage global temperature Mean power radiated
A constant increases
B constant decreases
C increases increases
D increases constant