Black Bodies Flashcards
1
Q
Black Body Definition
A
- Ideal absorber of all radiation that strikes the body
- Ideal emitter of radiation at the same time
2
Q
Stephan Boltzmann Law
A
I = σT^4
3
Q
Blackbody Radiation Spectrum
A
- Continuous spectrum of radiation emitted by a black body
- I(λ) is spectral emittance
- As temperature increases, peak grows and shifts to shorter λ
4
Q
Wien’s Displacement Law
A
λmax T = 2.898 x 10^-3
5
Q
Rayleigh-Jeans Law (Classical Approach)
A
- Leads to UV catastrophe
- As wavelength decreases, I(λ) tends to infinity
- I(λ) ~ T/λ^4
6
Q
Plancks Model of BB
A
- Quantised Energy
- Allowed Energy levels E = nhf
- Average Energy = hf/ exp(hf/kbT) -1
