# $\mu$ and $\in _0$ denote the permeability and permitting of free space, the dimensions of $\mu_0\in _0$ are

$(a)\;LT^{-1} \quad (b)\;L^{-2}T^{2} \quad (c)\;M^{-1}L^{-3}Q^2T^2 \quad (d)\;M^{-1}L^{-3}I^2T^2$

We Know $\large\frac{1}{\sqrt {\mu_0 \in_0}}=c$
Where $c$ is velocity of light.
Therefore $\mu_0 \in _0=\large\frac{1}{c^2}$
$\mu_0 \in_0=\large\frac{1}{[LT^{-1}]^2}$
$\qquad=[L^{-2}T^{2}]$
The dimensions of $\mu_0 \in_0$ are $L^{-2}T^{2}$
Hence b is the correct answer.

edited Jan 9, 2014 by meena.p