Question

A magnetic field 2 × 10^–2T acts at right angles to a coil of area 200 cm² with 25 turns. The average emf induced in the coil is 0.1 v when it removes from the field in time t. The value of t is 

(a) 0.1 sec 

(b) 1 sec 

(c) 0.01 sec 

(d) 20 sec

Answer 1

The correct option (a) 0.1 sec

Explanation:

B = 2 × 10^–2T

A = 200 cm² = 200 × 10^–4m²

N = 25

e = 0.1 v

we know e = – N(dɸ/dt)

∴ hence e = [(NAB)/t]

∴ t = [(NAB)/e] = [{25 × 2 × 10^–2 × 200 × 10^–4}/{0.1}]

∴ t = 0.1 sec