PHYSICS · Multi-part · Fermi University Physics · Electricity, Magnetism & Electromagnetism · Electromagnetic induction and alternating-current circuits · Electromagnetic induction and alternating-current circuits
Electricity, Magnetism and Electromagnetism, Ch Faraday's law, motional emf and Lenz's law
Problem
A horizontal copper ring is held fixed in a clamp. A short bar magnet is released above it, south pole downwards, and falls along the axis of the ring, passing right through it. Air resistance on the magnet is ignored, and the ring's own field is far weaker than the magnet's.
((a)) While the magnet is above the ring and approaching it, is the induced current in the ring clockwise or anticlockwise as seen from above?
((b)) After the magnet has passed through and is falling away below the ring, is it clockwise or anticlockwise as seen from above?
((c)) In each stage, is the force that the ring exerts on the magnet upwards or downwards?