A metal disc of radius 100 cm is rotated at a constant angular speed of `60 rad//s` in a plane at right angles to an external field of magnetic induction `0.05 Wb//m^(2)`. The emf induced between the centre and a point on the rim will be

Options

A. 3V
B. 1.5 V
C. 6V
D. 9V

Answer

B

Explanation

Induced emf produced between the centre and a point on the disc is given by
`e=(1)/(2)omega BR^(2)`
Putting the values,
`omega = 60 rad//s, B=0.05 Wb//m^(2)` and R = 100 cm = 1m
We get `e=(1)/(2)xx 60xx0.05xx(1)^(2)=1.5V`