WAEC Physics 2022 Theory — Question 6

Model answer

(a) The S.I. unit of the intensity of a blackbody radiation is Wm⁻² or Js⁻¹m⁻². The intensity I(λ,T) of blackbody radiation depends on the wavelength λ of the emitted radiation and the temperature of the blackbody. It is the power radiated per unit area. Radiation emitted by materials approximately follows the blackbody radiation curve. (b) Features of the intensity-wavelength graph of a perfect blackbody at different temperatures: - Shape of the curve is non-symmetric. - The line joining the peaks has a negative gradient. - Peaks decrease with wavelength. - Each curve corresponds to a different blackbody temperature, starting from a low temperature (lowest) curve to a high temperature (highest) curve.