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.

(N/A) When a cylindrical bar magnet is dropped through the metallic pipe,the magnetic flux linked with the pipe changes as the magnet falls.
According to Faraday's law of electromagnetic induction,this change in magnetic flux induces eddy currents in the metallic pipe.
According to Lenz's law,these eddy currents create a magnetic field that opposes the motion of the falling magnet.
Consequently,the magnet experiences an upward retarding force,causing its acceleration to be less than the acceleration due to gravity $(g)$.
In contrast,when an unmagnetised iron bar is dropped,there is no change in magnetic flux,and no eddy currents are induced.
Therefore,the unmagnetised iron bar falls with an acceleration equal to $g$,taking less time to pass through the pipe compared to the bar magnet.