A150 turn circular coil has diameter of 5.25cm and is connected to a load with resistance of 10 ohms. a magnetic field perpendicular to the coil is changing at a rate of 1.0 t/s. a) calculate the magnitude of the emf.
b) calculate the magnitude of the induced current flowing through the load.
c) what is the value of the current if a second resistor of 20 ohms is connected in series with the first one?

(a) 0.325 V

(b) 0.0325 A

(c) 0.011 A

Explanation:

N = 150

diameter = 5.25 cm

radius, r = diameter / 2 = 2.625 cm = 0.02625 m

R = 10 ohm

dB / dt = 1 T/s

(a) Let e be the magnitude of induced emf

e = rate of change of magnetic flux

e = dФ / dt

e = N x A x dB / dt

e = 150 x 3.14 x 0.02625 x 0.02625 x 1 = 0.325 V

(b) induced current , i = induced emf / R = 0.325 / 10 = 0.0325 A

(c) When 10 ohm is connected in series with 20 ohm, then equivalent resistance is 10 + 20 = 30 ohm

induced current, i = 0.325 / 30 = 0.011 A

current flows in a wire

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach