Question

Consider a metallic pipe with an inner radius of $1$ cm. If a cylindrical bar magnet of radius $0.8cm$ is dropped through the pipe, it takes more time to come down than it takes for a similar unmagnetized cylindrical iron bar dropped through the metallic pipe. Explain

Answer 1

When a cylindrical bar magnet is dropped through the metallic pipe, eddy current are produced in the metallic pipe. These currents will oppose the motion of the magnet.
Therefore, magnet’s downward acceleration will be less than the acceleration due to gravity g. On the other hand, an unmagnetized iron bar will not produce eddy currents and will fall with an acceleration g. Thus, the magnet will take more time.

Final answer: Due to eddy currents.