Q45 / 110 · NTA Abhyas (NEET) 2020 · Physics · Units and Dimensions

The unit of Stefan's constant $σ$ is

A
$W m^{- 2} K^{- 1}$
B
$W m^{2} K^{- 4}$
Correct answer
C
$W m^{- 2} K^{- 4}$
D
$W m^{- 2} K^{4}$

Solution

Stefan's law is $E = σ (T^{4})$ $\Rightarrow$ $σ = \frac{E}{T^{4}}$

where, $E =$ $\frac{Energy}{Area \times Time}$ $= \frac{Watt}{m^{2}}$

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

Hence, the correct answer is option: 'C'.

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