Question

3. The following figure shows you a circular loop with radius 10 cm. A magnetic field is DECREASING from 1.5 T to 0.5 T in 4 mili - seconds. The angle 8 = 60 degrees. Compute the induced EMF in the loop. • If the resistance of the loop is of 5 ohms, what is the value of the induced current. • What is the direction of the induced current?

Answer 1

Area of the loop, A = $\pi$ r² = (3.14*0.1²) m²

= 0.0314 m²

Induced emf = - A cos60^o(dB/dt)

= -0.0314*0.5*(0.5-1.5)/4*10^-3

= 3.925 volt

Current, I = emf/resistance = (3.925/5) = 0.785 A

By Lenz's law, the direction of current is such that it opposes the decreasing magnetic field, so, current will flow in anticlockwise direction if one observe from right side.