Question

A copper disc or radius 0.1 m rotates about its axis in a uniform magnetic field of 0.1. Tesla at 10 rotations per second. the plane of the disc remains normal to the magnetic field. The induced emf along the radius of the disc will be

• A. $\frac{\pi }{10}volt$
• B. $\frac{2\pi }{10}volt$
• C. $\frac{\pi }{100}volt$
• D. $2\pi volt$

Answer 1

Answer: (C)

$\frac{\pi }{100}volt$

$emf={\int }_0^{R}Br\omega dr$
$=\frac{B\omega R^2}{2}$
$=0.1\times 2\pi 10\times \frac{{0.1}^2}{2}$
$=\frac{\pi }{100}V$