Question

If a graph is plotted by taking spectral emissive power along $y-$axis and wavelength along x-axis is:

• A. Emissivity
• B. Total intensity of radiation
• C. Diffusivity
• D. Solar constant

Answer 1

The correct option is A Emissivity

Emissive power varies according to Stefan-Boltzmann law as :

$E=\sigma T^4$

According to Planck’s distribution law:

$E_{\lambda }(\lambda ,T)=\frac{C_1}{{\lambda }^5\left[\exp \right(\frac{C_2}{\lambda T})-1]}$

The graph shows that the emitted radiation varies with wavelength and also it shows Emissivity.