Question

A long solenoid having 400 turns per
of cross-sectional area 4 cm’ is placed
co-axially inside the solenoid so that
the coil is in the field produced by the
solenoid. Find the emf induced in the
coil if the current through the solenoid
reverses its direction in 0.04 sec.
​Answer : 0.20V

Answer 1

Answer:

Number of turns of long solenoid per cm = 400/10^−2; N2 = 400 x 10^2

Number of turns inside the solenoid, N2 = 100

Cross-sectional area of the coil, A = 4 cm2 = 4 x 10-4 m2

Current through the solenoid, I = 2A;

time, t = 0.04 s

Induced emf of the coil, e = −M*dI/dt

The current through the solenoid reverse its direction if the induced emf, e = -0.2 V