Eddy Currents
Strong spherical neodymium magnet is given free fall through the thick walled hollow copper cylinder, due Eddy current it descends with slow velocity
Whenever magnetic flux linked with the coil or conductor changes emf is generated and so current loops , the magnetic field due to it opposes the motion of the conductor (here magnet)
Induced emf or induced current is produced in such a way that the magnetic field produced due to it opposes very cause