Black Bodies Final Flashcards
1
Q
Black Body Definition
A
A BB is an ideal absorber of all radiation that strikes it.
It is an ideal emitter at the same time
2
Q
Classical Approach to Spectral Emittance
A
- I(λ) ~ T/λ^4
- Good approximation as λ -> infinity
- Does not work for λ -> 0
- Leads to the UV catastropher
3
Q
Plancks Approach to Spectral Emittance
A
- Quantised energy into discrete units
- E = nhf
- Average energy = hf / exp(hf/kBT) -1
- I(λ) = (2πhc^2/λ^5) (1/ exp(hf/λkBT) -1
4
Q
Wien’s Displacement Law
A
λmax T = 2.898 x 10^-3
5
Q
Stephan Boltzmann Law
A
I = σT^4
