Question

A fixed 13.6-cm diameter wire coil is perpendicular to a magnetic field 0.4 T

pointing up. In 0.30s, the field is changed to 0.24T pointing down.

What is the average induced emf in the coil?

Answer 1

Given data

diameter, d = 13.6 cm = 13.6*10^-2 m = 0.136 m

=> radius = d/2 = 0.136/2 = 0.068 m

time t = 0.3 s

induced emf = rate of change of flux

               E = d(BA)/dt

                  = A * dB/dt

                  = { [ pi * (0.068)^2 ] *[0.4 - (-0.24) ] } / 0.3

                  = 0.031 Volt ......Ans