Question

In a coil of area 10 cm² and 10 turns with a magnetic field directed perpendicular to the plane and is changing at the rate of 10⁸ gauss/second. The resistance of the coil is 20 ohm. The current in the coil will be(a) 5 amp(b) 0.5 amp(c) 0.05 amp(d) 5 ×10⁸ amp

Answer 1

answer : option (c) 0.05 ampere.

explanation : cross sectional area , A = 10cm² = 10 × 10^-4 = 10^-3 m²

number of turns, N = 10

change of magnetic field per unit time , $\frac{dB}{dt}$ = 10^8 Gauss /s = 10⁴ T/s

resistance of coil , R = 20 ohms

now, induced emf = - $\frac{d\phi}{dt}$

= -$NA\frac{dB}{dt}$

= - 10 × 10^-3 × 10⁴ = - 1V

hence, induced emf = 1V

now, induced current = induced emf/R

= 1/20 = 5/100 = 0.05 Ampere

hence, option (c) is correct