Question

A magnet is situated near a closed conductor. Current can be produced in the conductor if:

• A. only magnet is in motion
• B. only conductor is in motion
• C. both magnet and conductor are in motion
• D. there is relative motion between magnet and conductor

Hint:

Relative motion between magnet and conductor causes changing magnetic flux, inducing current.

Answer 1

The Correct Option is D

According to Faraday’s law of electromagnetic induction, an electromotive force (emf) is induced in a conductor only when there is a change in the magnetic flux linking the conductor. Mathematically, the induced emf \( \mathcal{E} \) is given by: \[ \mathcal{E} = -\frac{d\Phi_B}{dt}, \] where \( \Phi_B \) is the magnetic flux through the conductor. This change in flux can occur due to the relative motion between the magnet and the conductor, such as moving the magnet closer or farther, or moving the conductor through a magnetic field. Without this relative motion, the magnetic flux remains constant, and no emf is induced. Therefore, the essential condition for electromagnetic induction is a changing magnetic flux, which is achieved by the relative movement between the magnet and the conductor.