Question

when the north pole of a bar magnet is moved into a solenoid, the needle on a galvanometer attached to the solenoid moves to the left, indicating that a current is produced. the magnet is then pulled out at a faster speed. what will be the result? a larger current in the same direction a larger current in the opposite direction a smaller current in the same direction a smaller current in the opposite direction

Explanation:

1. Lenz's Law and Direction: When the north pole of the magnet is moved into the solenoid, a current is induced (galvanometer left). When the magnet is pulled out, the change in magnetic flux is opposite (flux decreasing in the original direction), so the induced current direction reverses (opposite to the initial direction when inserting).
2. Faraday's Law and Magnitude: Faraday’s law states induced emf (and thus current) is proportional to the rate of change of magnetic flux. Pulling the magnet out faster increases the rate of flux change, so the induced current magnitude is larger.

Answer:

B. a larger current in the opposite direction