JEEPhysics

A magnetic field vector in an electromagnetic wave is represented by \(\vec{B}={B}_{0}\sin \left(2\pi \nu t-\frac{2\pi x…

Q1 FREE PREVIEW
PYQ

A magnetic field vector in an electromagnetic wave is represented by \(\vec{B}={B}_{0}\sin \left(2\pi \nu t-\frac{2\pi x}{\lambda }\right)\hat{j}\). Its associated electric field vector is ________

[JEE Main 2026, 4 Apr (Shift 2)]

a

\(\vec{E}=-\nu \lambda {B}_{0}\sin \left(2\pi \nu t-\frac{2\pi x}{\lambda }\right)\hat{k}\)

b

\(\vec{E}=-\nu \lambda {B}_{0}\sin \left(2\pi \nu t-\frac{2\pi x}{\lambda }\right)\hat{i}\)

c

\(\vec{E}=v\lambda {B}_{0}\sin \left(2\pi vt-\frac{2\pi x}{\lambda }\right)\hat{k}\)

d

\(\vec{E}=v\lambda {B}_{0}\sin \left(2\pi vt-\frac{2\pi x}{\lambda }\right)\hat{i}\)

✓ Correct answer: a)

\(\vec{E}=-\nu \lambda {B}_{0}\sin \left(2\pi \nu t-\frac{2\pi x}{\lambda }\right)\hat{k}\)

Explanation

\(\vec{B}={B}_{0}\sin \left(2\pi \nu t-\frac{2\pi x}{\lambda }\right)\hat{j}\)

Since spatial term contains only \(x\) with negative sign \((\omega t-kx)\), wave propagates along \(+\hat{x}\).

\(\hat{E}\times \hat{B}=\hat{C}\)

\(\hat{B}=\hat{j},\hat{C}=\hat{j}\)

\(\hat{E}\times \hat{j}-\hat{i}\Rightarrow \hat{E}=-\hat{k}\)

\({E}_{0}=c{B}_{0}=\nu \lambda {B}_{0}\)

\(\vec{E}=-\nu \lambda {B}_{0}\sin \left(2\pi \nu t-\frac{2\pi x}{\lambda }\right)\hat{k}\)

Practice more JEE Physics PYQs

See every question on Electromagnetic Waves, or browse the full JEE question bank.

See all questions on Electromagnetic Waves →