Question

The unit of Stefan's constant is

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

Answer 1

Answer: (C)

According to Stefan's law, the energy radiated per second or power radiated is given by $P=\sigma A{{T}^{4}}$ $\therefore$ $\sigma =\frac{P}{A{{T}^{4}}}$ Therefore, unit of $\sigma =\frac{W}{{{m}^{2}}{{K}^{4}}}=W{{m}^{-2}}{{K}^{-4}}$