Revision lecture Flashcards
(12 cards)
What is a blackbody
an idealised physical body that absorbs all incident electromagnetic radiation, at all wavelengths
What is blackbody radiation
the radiation emitted by a blackbody which is in thermal equilbrium with its environment
what is a black body radiator
if a black body is in thermal equilibrium then its temperature remains constant
what is Planks laww
the spectrum of radiation is determined by the temperature of the blackbody alone, the shape or composition does not affect the blackbody spectrum
what key properties does an ideal blackbody have
- ideal emitter = at every frequency, it emits as much or more thermal radiative energy as any other body at the same temperature
- diffuse emitter = the energy radiated is independent of direction of emission
what happens if the blackbody temperature is high
- the more thermal radiation it emits at all wavelengths
what radiation does the sun emit
infrared and UV
while its emission peak is in the visible spectrum
what is a shift in the peak of a spectrum called
displacement law
black body ____ all radiation falling on it and reemits it as a function of ________
- absorbs
- surface temperature
what does Stefan-blotzmann law suggest
warmer objects emit energy more intensely than cold objects
what does Weins law suggest
warmer objects emit a higher proportion of their energy at short wavelengths than cold objects
