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JEE Main 202524 JanuaryEvening Shift
Exam
JEE Main
Year
2025
Date
24 January
Shift
Evening Shift
Subject
Physics
Chapter
Magnetic Effects of Current

JEE Main 2025 · 24 January · Evening Shift · Physics · Magnetic Effects of Current

N equally spaced charges each of value q , are placed on a circle...

N equally spaced charges each of value q , are placed on a circle of radius R . The circle rotates about its axis with
N equally spaced charges each of value q , are placed on a circle of radius R . The circle rotates about its axis with an angular velocity ω\omega as shown in the figure. A bigger Amperian loop B encloses the whole circle where as a smaller Amperian loop A encloses a small segment. The difference between enclosed currents, IA−IBI_A-I_B, for the given Amperian loops is

Options

  1. A2πNqω\frac{2 \pi}{N} q \omega
  2. BN22πqω\frac{\mathrm{N}^2}{2 \pi} \mathrm{q} \omega
  3. CNπqω\frac{\mathrm{N}}{\pi} \mathrm{q} \omega
  4. DN2πqω\frac{\mathrm{N}}{2 \pi} \mathrm{q} \omega

Correct answer

D. N2πqω\frac{\mathrm{N}}{2 \pi} \mathrm{q} \omega

Step-by-step solution

N equally spaced charges each of value q , are placed on a circle of radius R . The circle rotates about its axis with
IA=Nq2πωIA=Nqω2π,IB=0IA=IB=Nqω2π\begin{aligned} & I_A=\frac{N q}{\frac{2 \pi}{\omega}} \\ & I_A=\frac{N q \omega}{2 \pi}, I_B=0 \\ & I_A=I_B=\frac{N q \omega}{2 \pi}\end{aligned}
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