Question

The unit of Stefan's constant $\sigma$ is

• A. $W{m}^{-2}{K}^{-1}$
• B. $W{m}^2{K}^{-4}$
• C. $W{m}^{-2}{K}^{-4}$
• D. $W{m}^{-2}{K}^4$

Answer 1

The correct option is C $W{m}^{-2}{K}^{-4}$

Stefan's law is $E=\sigma \left(T^4\right)\Rightarrow \sigma =\frac{E}{T^4}$
where, $\left[E\right]=\left[\frac{\text{Energy}}{\text{Area}\times \text{Time}}\right]=\frac{\text{Watt}}{m^2}$
$\therefore \left[\sigma \right]=\frac{\text{Watt}{m}^{-2}}{K^4}=W{m}^{-2}{K}^{-4}$