Radiation

• What do all bodies (objects) emit and absorb?

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

  More infrared radiation is emitted.
• What happens to the type of radiation emitted by an inject as temperature increases?

  The hotter the body the shorter the wavelength of radiation released.
• What is required for a body to be at constant temperature?

  The body would need to emit radiation at the same rate it absorbs it - it needs to radiate at the same average power that it absorbs.
• What is meant by intensity?

  The power transferred per unit area; it is a measure of the energy transferred by a wave.
• What will happen if the average power that an object radiates is less than it absorbs?

  The temperature of the object will decrease.
• What can be said about the rates of emission and absorption for a body increasing in temperature?

  The body is absorbing radiation faster than it is emitting it.
• Give two factors that affect the temperature of the Earth

  The Earth’s rate of absorption and emission of radiation, the amount of reflection of radiation into space.
• How does the Earth‘s atmosphere affect radiation?

  The atmosphere largely absorbs or reflects radiation from the sun, preventing it from reaching Earth. Some radiation, however, is alllowed to pass through and warms the earth.
• What happens to the radiation emitted from the Earth?

  It is absorbed by and re-emitted in all directions by greenhouse gases, resulting in the greenhouse effect which warms the earth.