Electromagnetic Waves

JEE Main level, single correct, medium

32 of 165

Question 32 of 165

Electromagnetic waves travel in a medium with speed of 1.5×108 m s−11.5 \times 10^8 \mathrm{~m} \mathrm{~s}^{-1}. The relative permeability of the medium is 2.0 . The relative permittivity will be:

Show answer and solution

Answer: (A) 2

εm×μmε0×μ0=1v21c2εr×μr=c2v2εr×2=(3×108)2(1.5×108)2εr×2=4εr=2\begin{aligned} & \frac{\varepsilon_{\mathrm{m}} \times \mu_{\mathrm{m}}}{\varepsilon_0 \times \mu_0}=\frac{\frac{1}{\mathrm{v}^2}}{\frac{1}{\mathrm{c}^2}} \\ & \varepsilon_{\mathrm{r}} \times \mu_{\mathrm{r}}=\frac{\mathrm{c}^2}{\mathrm{v}^2} \\ & \varepsilon_{\mathrm{r}} \times 2=\frac{\left(3 \times 10^8\right)^2}{\left(1.5 \times 10^8\right)^2} \\ & \varepsilon_{\mathrm{r}} \times 2=4 \\ & \varepsilon_{\mathrm{r}}=2\end{aligned}

JEE Main question paper PDF

Open a shift to read the full paper on this page, or download it.

JEE Main 2025 Apr 2 Shift 1 question paper

Open Download PDF

Opening paper…

Explain it as a whiteboard videoStep-by-step, in Hinglish or English. Your first video needs no login.Solved it on paper but got it wrong?Upload a photo of your working. Mistake Doctor marks the exact line that broke.

More Physics practice

JEE Main Physics practice question on Electromagnetic Waves (Electromagnetic Waves and Maxwell's equations), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.