Question

A 500-turn circular coil with an area of 0.050 m^2 is mounted on a rotating frame, which turns at a rate of 20.0 rad/s in the presence of a 0.050-T uniform magnetic field that is perpendicular to the axis of rotation. What is the instantaneous emf in the coil at the moment that the normal to its plane is at a 30.0 degree angle to the field?

a) zero
b) 12.5 V
c) 21.6 V
d) 25.0 V

Answer 1

option (b) 12.5 V

Explanation:

Given:

Number of turns, N = 500

Area of the coil, A = 0.050 m²

Angular speed, ω = 20 rad/s

Magnetic field, B = 0.050 T

Angle to the field, θ = 30°

Now,

EMF induced, ε = NBAωsinθ

on substituting the values, we get

ε = 500 × 0.050 × 0.050 × 20 × sin30°

or

ε = 25 × 0.5

or

ε = 12.5 V

Hence,

option (b) 12.5 V