Question

1. A square wire loop 10cm on a side is oriented with its plane perpendicular to a magnetic field. The resistance of the loop is 5.0. How rapidly should the magnetic field change if a current of 2.0 A is to flow in the loop?

Answer 1

According to Ohm's law, find the voltage:

$$V=IR.$$

Using Faraday's law, express the voltage in terms of change of magnetic flux:

$$V=\frac{\Delta \Phi}{\Delta t}=\frac{A\Delta B}{\Delta t},\\\space\\ \frac{\Delta B}{\Delta t}=\frac VA=\frac{IR}{a^2}=1000\text{ T/s}.$$