A copper disc of radius `0.1 m` rotates about its centre with `10` revolutuion per second in a uniform magnetic field of `0.1` tesla with its plane perpendicular to the field. The emf induced across the radius of the disc is

Options

A. `(pi)/(10)` volt
B. `(2pi)/(10)` volt
C. `pi xx 10^(-2)` volt
D. `2pi xx 10^(-2)` volt

Answer

C

Explanation

e.m.f. induced `=(1)/(2)BR^(2)omega = (1)/(2)BR^(2)(2pi n)`
`=(1)/(2)xx (0.1)xx(0.1)^(2)xx2pi xx 10=(0.1)^(2)pi` volts