Answer
See answers.
Work Step by Step
a. Magnetic field lines point into the paper. As the ring shrinks, the number of magnetic field lines pointing into the paper decreases with time.
The induced current in the loop will cause a field to oppose this change in magnetic flux. The secondary field makes magnetic field lines also into the paper, to replace field that is lost. By the right hand rule, a clockwise induced current appears in the ring.
b. Find the magnitude of the average induced emf by using equation 21–2a.
$$|\epsilon_{av}|=\frac{B|\Delta A|}{\Delta t}=\frac{(0.65T)\pi((0.100m)^2-0.030m)^2}{0.50s}=0.037V$$
c. Find the average induced current from Ohm’s law.
$$I-\frac{\epsilon}{R}=\frac{0.03717V}{2.5\Omega}=0.015A$$