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Question: Answered & Verified by Expert
Using mass $(M)$, length $(L)$, time $(T)$ and current $(A)$ as fundamental quantities, the dimension of permittivity is
PhysicsUnits and DimensionsAIIMSAIIMS 2004
Options:
  • A $\left[\mathrm{ML}^{-2} \mathrm{~T}^2 \mathrm{~A}\right]$
  • B $\left[\mathrm{M}^{-1} \mathrm{~L}^{-3} \mathrm{~T}^4 \mathrm{~A}^2\right]$
  • C $\left[\mathrm{MLT}^{-2} \mathrm{~A}\right]$
  • D $\left[\mathrm{ML}^2 \mathrm{~T}^{-1} \mathrm{~A}^2\right]$.
Solution:
2429 Upvotes Verified Answer
The correct answer is: $\left[\mathrm{M}^{-1} \mathrm{~L}^{-3} \mathrm{~T}^4 \mathrm{~A}^2\right]$
Force of attraction between two charges is given by
$$
\begin{aligned}
F & =\frac{1}{4 \pi \varepsilon_0} \frac{q_1 q_2}{r^2} \\
\Rightarrow \quad \varepsilon_0 & =\frac{1}{4 \pi} \frac{1}{F} \frac{q_1 q_2}{r^2}=\frac{\mathrm{A}^2 \mathrm{~T}^2}{\mathrm{MLT}^{-2} \mathrm{~L}^2} \\
& =\left[\mathrm{M}^{-1} \mathrm{~L}^{-3} \mathrm{~T}^4 \mathrm{~A}^2\right] .
\end{aligned}
$$
(where $4 \pi$ is dimensionless)
$=\left[\mathrm{M}^{-1} \mathrm{~L}^{-3} \mathrm{~T}^4 \mathrm{~A}^2\right]$

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