Question

A bar magnet is held with its length along the axis of a closed coil. Initially, the south pole of the magnet faces the coil. If the magnet is moved towards the coil, explain how a current is induced in the coil and in what direction.

Hint:

\textbf{Lenz's Law} states that the direction of the induced current will always oppose the change in magnetic flux. This ensures that energy is conserved during electromagnetic induction.

Answer 1

A current is induced in a coil when a bar magnet approaches it, altering the magnetic flux. This is governed by Faraday's Law of Induction, which posits that a changing magnetic flux through a coil generates an electromotive force (emf). Induced Current Characteristics:1. Direction: - Lenz's Law dictates that the induced current opposes the magnetic flux change. - As the south pole of the approaching magnet increases the magnetic flux towards the coil, the coil generates a current. This current creates its own magnetic field, acting as a north pole facing the approaching south pole. 2. Nature: - The induced current opposes the magnet's south pole by producing a counteracting magnetic field. - The precise direction of this opposing current is determined by the right-hand rule for coils.3. Right-Hand Rule Application: - For solenoids, the right-hand rule correlates current direction with the internal magnetic field direction: curl right-hand fingers with current, thumb indicates magnetic field. - To oppose the approaching south pole, the coil must form a north pole on its magnet-facing side.Consequently, the coil's induced current generates a magnetic field that counteracts the flux increase caused by the approaching south pole. Conclusion: The induced current flows to create a magnetic field that repels the incoming south pole of the magnet.