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Question: Answered & Verified by Expert
In terms of resistance $R$ and time $T$, the dimensions of ratio $\frac{\mu}{\varepsilon}$ of the permeability $\mu$ and permittivity $\varepsilon$ is:
PhysicsUnits and DimensionsJEE MainJEE Main 2014 (11 Apr Online)
Options:
  • A
    $\left[\mathrm{RT}^{-2}\right]$
  • B
    $\left[\mathrm{R}^2 \mathrm{~T}^{-1}\right]$
  • C
    $\left[\mathrm{R}^2\right]$
  • D
    $\left[\mathrm{R}^2 \mathrm{~T}^2\right]$
Solution:
2013 Upvotes Verified Answer
The correct answer is:
$\left[\mathrm{R}^2\right]$
Dimensions of $\mu=\left[\right.$ MLT $\left.^{-2} \mathrm{~A}^{-2}\right]$
Dimensions of $\in=\left[\mathrm{M}^{-1} \mathrm{~L}^{-3} \mathrm{~T}^4 \mathrm{~A}^2\right]$
Dimensions of $\mathrm{R}=\left[\mathrm{ML}^2 \mathrm{~T}^{-3} \mathrm{~A}^{-2}\right]$
$$
\begin{aligned}
&\therefore \frac{\text { Dimensions of } \mu}{\text { Dimensions of } e}=\frac{\left[\mathrm{MLT}^{-2} \mathrm{~A}^{-2}\right]}{\left[\mathrm{M}^{-1} \mathrm{~L}^{-3} \mathrm{~T}^4 \mathrm{~A}^2\right]} \\
&=\left[\mathrm{M}^2 \mathrm{~L}^4 \mathrm{~T}^{-6} \mathrm{~A}^{-4}\right]=\left[\mathrm{R}^2\right]
\end{aligned}
$$

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