Answer
a. Right to left.
b. Right to left.
c. Left to right.
Work Step by Step
By Lenz’s Law, the field caused by the induced current is directed to oppose the change in flux.
a. The magnetic field in winding A points to the left and is increasing. This increases the flux through B, so the induced current in B makes a field to the right. To produce magnetic field to the right, the induced current flows through R from right to left.
b. The magnetic field in winding A points to the right and is decreasing. This decreases the flux through B, so the induced current in B makes a field to the right, to reinforce the failing field. To produce magnetic field to the right, the induced current flows through R from right to left.
c. The magnetic field in winding A points to the right and is increasing. This increases the flux through B, so the induced current in B makes a field to the left, to fight the upstart field. To produce magnetic field to the left, the induced current flows through R from left to right.
