Physical World Units And Measurements Ques 8

8. The dimension of $\frac{1}{2} \varepsilon_0 E^{2}$, where $\varepsilon_0$ is permittivity of free space and $E$ is electric field, is:

[2010]

(a) $[ML^{2} T^{-2}]$

(b) $[ML^{-1} T^{-2}]$

(c) $[ML^{2} T^{-1}]$

(d) $[MLT^{-1}]$

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Answer:

Correct Answer: 8.(b)

Solution:

  1. (b) $\frac{1}{2} \varepsilon_0 E^{2}$ represents energy density i.e., energy per unit volume.

$\Rightarrow[\frac{1}{2} \varepsilon_0 E^{2}]=\frac{[M L^{2} T^{-2}]}{[L^{3}]}=[ML^{-1} T^{-2}]$