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

Explanation

When cylinderical bar magnet of radius 0.8cm is dropped through the metallic pipe with an inner radius of 1cm, flux linked with the cylinder changes and consequently eddy currents are produced in the metallic pipe. According to Lenz's law. These curents will oppose the (cause) motion of the magnet.
Therefore, magent's downward acceleration will be less than the acceleration due to gravity g. On the other hand, an unmagetised iron bar will not produce eddy currents and will fall with an acceleration due to gravity g.
Thus the magnet will take more time to come down than it takes for a simialr unmagnetised cylinderical iron bar dropped through the metallic pipe.