Start free

Physics · Electromagnetic Induction

JEE Main 2025 — 29 January, Morning Shift — Question 33

A coil of area A and N turns is rotating with angular velocity ω\omega in a uniform magnetic field B→\overrightarrow{\mathrm{B}} about an axis perpendicular to

B→\overrightarrow{\mathrm{B}}. Magnetic flux φ\varphi and induced emf

ε\varepsilon across it, at an instant when B→\overrightarrow{\mathrm{B}} is parallel to the plane of coil, are :

  1. Option A:

    φ=AB,ε=0\varphi=\mathrm{AB}, \varepsilon=0

  2. Option B:

    φ=0,ε=NABω\varphi=0, \varepsilon=\mathrm{NAB} \omega

    Correct
  3. Option C:

    φ=0,ε=0\varphi=0, \varepsilon=0

  4. Option D:

    φ=AB,ε=NABω\varphi=\mathrm{AB}, \varepsilon=\mathrm{NAB} \omega

Answer: B

Step-by-step solution

ϕ=BAN⋅cos⁡(ωt)\phi=\mathrm{BAN} \cdot \cos (\omega \mathrm{t})

ε=−dϕdt=BAωN⋅sin⁡(ωt)\varepsilon=\frac{-\mathrm{d} \phi}{\mathrm{dt}}=\mathrm{BA} \omega \mathrm{N} \cdot \sin (\omega \mathrm{t}) When B is parallel to plane,

ωt‾‾=π2\underline{\underline{\omega t}}=\frac{\pi}{2}

⇒ϕ=0,ε=BAωN\Rightarrow \phi=0, \varepsilon=\mathrm{BA} \omega \mathrm{N}

Solution figure

Answer key and solution verified before publishing.

Practise Electromagnetic Induction

Start with this question, then two more from the same chapter — with a tutor that explains every step. Free.

Solve a similar one free
Exam
JEE Main 2025
Paper
29 January, Morning Shift
Subject
Physics
Chapter
Electromagnetic Induction
Topic
Magnetic Flux, Faraday's Law and Lenz's Law

More Electromagnetic Induction questions from this paper

A coil of area A and N turns is rotating with angular velocity ω in a… | JEE Main 2025 PYQ with Solution · DhiX AI