waves - black body radiation Flashcards
what is the best absorbers and emitters of infrared radiation?
matt black surfaces
what do all objects no matter what temperature emit and absorb?
infrared radiation
what will a hotter object emit more of?
infrared radiation in a give time compared with a cooler object
what does wavelength and intensity of radiation depend on?
temperature of an object
very hot objects emit?
short wavelength radiation than cooler objects
why do very hot objects produce visible light?
as they emit short wavelength radiation than
when does intensity of radiation increase?
at higher temperature
what does a perfect black body do?
absorbs all radiation incident on it. no radiation reflected or transmitted. also best possible emitter of radiation
what will happen if an object is warmer than its surroundings?
emit more radiation than it absorbs + temp will decrease
what will happen if an object is cooler than its surroundings?
absorb more radiation than it emits causing temp to increase
e.g burgers on a barbecue
what happens if an object is at a constant temperature?
it is absorbing radiation at same rate as it is emitting radiation
how can earth gain or lose energy?
by absorbing or emitting radiation
what type of radiation does the sun emit? where does it travel?
short wavelength radiation such as visible light and ultraviolet light which then travels to the earth
what happens to radiation emitted by the sun to earth?
- some reflected e.g by clouds
- remaining radiation then absorbed by surface of earth causing temp of earth to increase causing infrared to be emitted again
- however some energy of infrared is trapped by greenhouse gases in the atmosphere e.g carbon dioxide
what is human activity increasing?
levels of greenhouse gases meaning more heat energy trapped in atmosphere and less radiated into space
