Question

100turns of insulated wire are wraped around a wooden cylindrical core of cross-sectional area 12cm2. The two ends of the wire are connected to a resistor. The total circuit resistance is 13Ω. If an externally applied uniform magnetic field along the core changes from 1.6T in one direction to 1.6T in the opposite direction, how much charge in Coulombs flows through the circuit during the change?

Answer 1

Pick some time over which the dB/dt takes place, say t = one second. Then dB/dt = 3.2/1 = 3.2 T/s
then you can get i for that dB/dt
then i * t = i * one second

Answer 2

not sure how to get i