6.3 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 3

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

Answer 3

none.

Question 4

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

Answer 4

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

Question 4

why is a perfect black body the best possible emitter of radiation?

Answer 4

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

Question 5

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

Answer 5

the body is absorbing and emitting radiation at the same rate.

Question 6

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

Answer 6

the body is absorbing radiation faster than it is emitting it.

Question 7

give two factors that affect the temperature of the earth.

Answer 7

1. the earth’s rate of absorption and emission of radiation
2. the amount of reflection of radiation into space