Black-Bodies and Colours Flashcards
1
Q
What are
Black-Bodies
A
- BBs are perfect emitters
- Absorb all incoming radiation
- B_λ is power emitted per unit area per unit wavelength
2
Q
Facts about
Black-Body spectra
A
- Spectra is smooth (differentiable and integratable)
- Cuts of sharply at short wavelengths (Wien’s Tail)
- Decline slowly at longer wavelengths (Rayleigh-Jeans Tail)
- B_λ increases at all wavelengths as temperature increases
- Peak shifts to smaller wavelengths as temperature increases
- Plotted as B_λ against wavelength
3
Q
What is the equation for
Wien’s Displacement Law
A
λ_max T = 2.898 x 10^-3
λ_max = wavelength of peak, T = Temperature
4
Q
What is the equation for
Stephan-Boltzmann Law
A
J = σ T^4
J = Total power emitter per unit area, σ = 5.67x10^-8, T = Temperature
5
Q
What is the equation for
Luminosity-Radius-Temperature relation
A
L = 4πR^2σT^4
L = luminosity, R = Radius, σ = 5.67x10^-8, T = Temperature
