6.3 Waves (black body radiation)

Question 1

What do all bodies (objects) emit and absorb?

Answer 1

infrared radiation

Question 2

What happens to the quantity of infrared radiation emitted by an object as temperature increases?

Answer 2

the hotter the object, the more infrared radiation it will emit

Question 3

What is a perfect black body?

Answer 3

an object that absorbs all of the radiation that is incident upon it

Question 4

How much radiation does a perfect black body reflect or transmit?

Answer 4

none

Question 5

Why is a perfect black body the best possible emiter of radiation?

Answer 5

• it is a perfect absorber since it absorbs all radiation incident on it
• a perfect absorber is also a perfect emitter

Question 6

Other than the intensity of radiation emitted, how does increasing the temperature of an object affect its emissions?

Answer 6

the wavelength distribution of any emission is dependent on the object’s temperature

Question 7

What can be said about the rates of emission and absorption for a body at a constant temperature?

Answer 7

the body is absorbing and emitting radiation at the same rate

Question 8

What can be said about the rates of emission and absorption for a body increasing in temperature?

Answer 8

the body is absorbing radiation faster than it is emitting it

Question 9

Give two factors that affect the temperature of the Earth?

Answer 9

1. The Earth’s rate of absorption and emission of radiation
2. The amount of reflection of radiation into space