Solenoids And Toroids

When a strong bar magnet moves towards a solenoid, it induces an electromotive force (EMF) in the solenoid due to electromagnetic induction. The direction of the induced current can be determined using Lenz's Law, which states that the direction of the induced current is always such that it opposes the change in magnetic flux that produced it. Let's analyze the problem step by step:

1. As the bar magnet approaches solenoid-1, the magnetic flux linked with solenoid-1 increases. To oppose this increase, the induced current in solenoid-1 will flow in such a direction that its own magnetic field opposes the field of the approaching magnet.
2. Using the right-hand rule, if the north pole of the bar magnet is moving towards solenoid-1, the induced current in solenoid-1 will flow in direction AB. This creates an induced magnetic field with its north pole facing the approaching bar magnet.
3. Now, consider solenoid-2. As the bar magnet moves away from solenoid-1 and approaches solenoid-2, it causes an increase in magnetic flux linking solenoid-2. Hence, the induced current in solenoid-2 will flow in such a direction that its magnetic field opposes the new incoming magnetic field.
4. Using Lenz's Law again, if we apply the right-hand rule to solenoid-2, the induced current in solenoid-2 will flow in direction DC, creating an induced magnetic field with its south pole facing the bar magnet.

Therefore, the correct option is AB and DC, where the induced current in solenoid-1 flows in direction AB and in solenoid-2 flows in direction DC respectively.