Black Body Radiation

Flashcards about Black Body Radiation and related physics laws

What is black body radiation?

The thermal electromagnetic radiation emitted by an idealized object

What is a black body?

A perfect emitter that absorbs all incident electromagnetic radiation without reflecting any; its radiation emission is only a function of its temperature.

What is Planck's Law?

Describes the spectral density of electromagnetic radiation emitted by a black body in thermal equilibrium at a given temperature.

What is Wien's Displacement Law?

λmax * T = b, where λmax is the wavelength at which emission is maximized, T is the absolute temperature, and b is Wien's constant.

What is the Stefan-Boltzmann Law?

P = σT^4, where P is the total power radiated per unit area, T is the absolute temperature, and σ is the Stefan-Boltzmann constant.

What does Kirchhoff's Law of Thermal Radiation state?

Emissivity 𝜖(𝜆) at a given wavelength is equal to the absorptivity 𝛼(𝜆) at the same wavelength: ϵ(λ) = α(λ)

What is the Prevost Theory of Exchange?

All bodies emit and absorb radiation simultaneously, with temperature determined by the balance between absorbed and emitted radiation.

What is the formula for Intensity Distribution in Black Body Radiation (Planck's Law)?

I(ν,T) = (2hν^3 / c^2) * (1 / (e^(hν/kBT) - 1))

What is the approximate intensity at T = 3000 K and ν = 5 × 10^14 Hz when calculated using Planck's Law?

approximately 4.17 × 10−7 W/m2/Hz

For a black body at T=6000 K, what is the total energy radiated per square meter?

Approximately 7.35 × 10^7 W/m^2

What is the wavelength of visible light emitted from the Sun’s surface temperature (T ≈ 5800 K)?

Approximately 500 nm corresponding to visible light, explaining why the Sun appears yellowish-white.