A permanent magnet is moved toward a 320-turn solenoid such that the magnetic field inside the solenoid increases from zero to 0.50 T in 0.75 s. The radius of the solenoid is 0.035 m.

Question

A permanent magnet is moved toward a 320-turn solenoid such that the magnetic field inside the solenoid increases from zero to 0.50 T in 0.75 s. The radius of the solenoid is 0.035 m. The ends of the solenoid are connected in series with a light bulb. What emf is induced during this time interval?

a) 47 V

b) 1.6 V

c) 5.7 V

d) .82 V

e) 0.051 V

Answer 1

EMF = Rate of change of magnetic flus

= NBA/Time

N= Number of turns,

A = area of cross section = pi * radius ²

B/ t Rate of change of magnetic field = (0.5/0.75) T/s

EMF = (320*0.5 *3.14 8 0.035 *0.035)/0.75 = 0.820 Volt

Choice(d) is correct