Q. Which of the following figures correctly depicts the Lenzs law? The arrows show the movement of the labelled pole of a bar magnet into a closed circular loop and the arrows on the circle show the direction of the induced current

 5093  208 Delhi UMET/DPMTDelhi UMET/DPMT 2009 Report Error

Solution:

According to Lenzs law when N-pole of a bar magnet moves towards the coil, the flux associated with loop increases and an emf is induced in it. Since, the circuit of loop is closed, induced current also flows in it. Cause of this induced current is approach of North Pole. In order to oppose the cause, ie, to repel the approaching north pole, the induced current is set up in the loop in such a direction so that the front face of loop behaves as North Pole. Therefore, induced current is in anticlockwise direction.