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

Answer: (C)

Stefan’s law $E=\sigma \left(T^4\right)\Rightarrow \sigma =\frac{E}{T^4}$

$E=\frac{\text{Energy}}{\text{Area}\times \text{Time}}=\frac{\text{watt}}{m^2}$

$\sigma =\frac{W-m^{-2}}{K^4}=W-m^{-2}{K}^{-4}$