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JEE Main 202228 JuneEvening Shift
Exam
JEE Main
Year
2022
Date
28 June
Shift
Evening Shift
Subject
Physics
Chapter
Electromagnetic Induction

JEE Main 2022 · 28 June · Evening Shift · Physics · Electromagnetic Induction

A coil is placed in a time varying magnetic field. If the number of...

A coil is placed in a time varying magnetic field. If the number of turns in the coil were to be halved and the radius of wire doubled, the electrical power dissipated due to the current induced in the coil would be (Assume the coil to be short circuited.)

Options

  1. ADoubled
  2. BThe same
  3. CQuadrupled
  4. DHalved

Correct answer

B. The same

Step-by-step solution

(\mathrm{P}=\frac{\varepsilon^2}{R}) where, (\varepsilon=) inducedemf (=-\frac{d \phi}{d t}) (\phi=\mathrm{NBA}) (\varepsilon=\mathrm{NA} \frac{\mathrm{dB}}{\mathrm{dt}}) also, (R \propto \frac{1}{\mathrm{r}^2}) where, (\mathrm{R}=) resistance and (\mathrm{r}=) radius of wire (P∝N2r2H2P1P2=1P1=P2\begin{aligned} & \mathrm{P} \propto \frac{\mathrm{N}^2 \mathrm{r}^2}{\mathrm{H}^2} \\ & \frac{\mathrm{P}_1}{\mathrm{P}_2}=1 \\ & \mathrm{P}_1=\mathrm{P}_2 \end{aligned}) This means if the number of turns were quadrupled and the wire radius halved, the electrical power dissipated would be remains same.
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