A short magnet is moved along the axis of conducting loops . Show that the loop repels the magnet if the magnet is approaching the loop and attracts the magnet if it is going away from the loop.

Question

Philoid · Accepted Answer

Lenz's law: The direction of the induced current is such that it opposes the magnetic field that has induced it.

See fig.(a). In that, the north pole is facing towards the loop. According to Lenz’s law, the direction of induced current will be anticlockwise. And the magnet is coming towards the loop. Then the flux through the loop will increase; it will create a magnetic field. This newly generated magnetic field will cancel the original magnetic field. Therefore the loops get repelled.

See fig.(b) in which the magnetic is moving away from the loop. It will lead to a decrease in the magnetic field intensity. Therefore, flux through the loop decreases. Therefore, flux through the loop decreases. According to Lenz's law in induced current produces a magnetic field in the opposite direction of the original field. Hence the loop attracts the magnet.

A short magnet is moved along the axis of conducting loops. Show that the loop repels the magnet if the magnet is approaching the loop and attracts the magnet if it is going away from the loop.