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}} $