Lenz's Law

In the figure, a straight wire carries a steady current I. A bar is in contact with a pair of circular rails, and rotates about the straight wire. The induced current through the resistor R is: A) from b to a B) zero C) from a to b

A rectangular coil lies flat on a horizontal surface. A bar magnet is held above the center of the coil with its north pole pointing down. What is the direction of the induced current in the coil? A) counterclockwise B) clockwise C) No current in the coil D) None of the previous is correct

In Figure 1, two parallel wires carry a current I in opposite directions. A rectangular loop is midway between the wires. The current I is decreasing. The induced current through the resistor R is:  A) from b to a B) from a to b C) zero

In the figure, a bar magnet moves away from the solenoid. The induced current through the resistor R is: A) zero B) from b to a C) from a to b

In Figure 1, a battery supplies a steady current to the solenoid on the left. The two solenoids are moving toward each other. The induced current through the resistor R is: A) from a to b B) from b to a C) zero

A long straight wire carries constant current I that is directed toward the left, as shown in the sketch. A small conducting loop is moving away from the wire with constant speed v. The current induced in the loop is A) zero B) clockwise C) counterclockwise

A bar magnet is dropped through a vertical copper tube and is observed to fall very slowly, despite the fact that mechanical friction between the magnet and the tube is negligible.  Which of following best explains the reason for this? A. The falling magnet magnetizes the copper pipe which causes the now permanent copper pipe magnet to attract the falling magnet thus causing the slower descent. B. The falling magnet is slowed by the Earth’s magnetic field. C. The changing flux of the falling magnet induces a magnetic field in the copper pipe, in the opposite direction of the bar magnet's field, which impedes the movement through the pipe. D. Friction and Air resistance cause the magnet to fall much slower than it would outside of the tube.

A single circular loop of wire in the plane of the page is perpendicular to a uniform magnetic field ~B directed into the page, as shown. If the magnitude of the magnetic field is decreasing, then the induced current in the wire loop is 1. counterclockwise around the loop. 2. directed upward out of the paper. 3. zero. (No current is induced.) 4. clockwise around the loop. 5. directed downward into the paper.

An equilateral triangular loop moves into a 0.50 T magnetic field with a constant speed of v = 5 m/s as shown. The loop has sides of length L = 0.50 m, a total resistance of 0.10 Ω, and it enters the field at t = 0 s. What is the direction of the induced current in the loop? Provide a complete justification for your answer.