Question

A rectangular coil of 20 turns and area of cross- section 25 sq cm has a resistance of 100 ohm. If a magnetic field which is perpendicular to the plane of the coil changes at the rate of 1000 Tesla per second, the current in the coil is(a) 1.0 ampere(b) 50 ampere(c) 0.5 ampere(d) 5.0 ampere

Answer 1

number of turns , N = 20

cross sectional area of coil, A = 25 cm² = 25 × 10^-4 m²

resistance of the coil , R = 100 ohm

rate of change of magnetic field , dB/dt = 1000T/s

a/c to question, magnetic field perpendicular to the plane of the coil.

so, induced emf = $\frac{d\phi}{dt}$ [question is just talking about magnetic that's why I didn't include sign ]

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

= 20 × 25 × 10^-4 × 1000

= 50 V

now, induced current = induced emf/R

= 50/100 = 0.5 Ampere

hence, option (c) is correct.