Question

Dimensions of ohm are same as (where $h$ is Planck's constant and $e$ is charge)

• A. $\frac{h}{e}$
• B. $\frac{h^2}{e}$
• C. $\frac{h}{e^2}$
• D. $\frac{h^2}{e^2}$

Answer 1

Answer: (C)

$\frac{h}{e^2}$

Answer 2

$\left[\frac{h}{e^{2}}\right]=\frac{\left[ML^{2}T^{-1}\right]}{\left[AT\right]^{2}}=\left[ML^{2}T^{-3}A^{-2}\right]$ [Resistance] $=\frac{\text{[Potential difference]}}{\text{[Current]}}$ $=\frac{\left[ML^{2}T^{-3}A^{-1}\right]}{\left[A\right]}=\left[ML^{2}T^{-3}A^{-2}\right]$ The $SI$ unit of resistance is ohm Therefore, the dimensions of ohm are same as that of $\frac{h}{e^{2}}$