Verified Solution • 2025–26 Session moderate

QJEEM23Phbe7a: JEE Main 2023 Physics - Class 12 JEEM23Phbe7a Solution: An emf of is induced in a metal rod of length held normal to a…

An emf of 0.08 V0.08 \mathrm{~V} is induced in a metal rod of length 10 cm10 \mathrm{~cm} held normal to a uniform magnetic field of 0.4 T0.4 \mathrm{~T} , when moves with a velocity of:

Multiple Choice Options

  • A 20 ms−120 \mathrm{~ms}^{-1}
  • B 2 ms−12 \mathrm{~ms}^{-1}
  • C 3.2 ms−13.2 \mathrm{~ms}^{-1}
  • D 0.5 ms−10.5 \mathrm{~ms}^{-1}

Step-by-Step Verified Solution

The emf induced in a rod moving through a magnetic field is given by Faraday's law of electromagnetic induction, specifically, in the form of motional emf, which states that:

emf=B⋅L⋅v\text{emf} = B \cdot L \cdot v

where:

  • (B) is the magnetic field strength,
  • (L) is the length of the rod, and
  • (v) is the velocity of the rod.

In this case, we are given the emf, (B), and (L), and we need to solve for (v). Rearranging the equation gives:

v=emfB⋅Lv = \frac{\text{emf}}{B \cdot L}

Substituting the given values:

v=0.08 V0.4 T×0.1 m=2 m/sv = \frac{0.08 \, \text{V}}{0.4 \, \text{T} \times0.1 \, \text{m}} = 2 \, \text{m/s}

Related Learning Resources & Exam Preparation