In Faraday's experiment on Electromagnetic Induction, in which of the following situations, more deflection will be shown by the galvanometer?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → magnet is accelerated towards the coil
By Faraday's law the induced emf is \( \varepsilon = -d\phi/dt \). The galvanometer deflection is larger when the flux changes faster, that is, when the magnet moves faster relative to the coil.
Option (1) magnet is at rest inside the coil — Incorrect. The flux does not change, so there is no emf and no deflection.
Option (2) magnet is accelerated towards the coil — Correct. The speed of the magnet keeps increasing, so the rate of change of flux keeps growing and the emf is the largest of the four cases.
Option (3) magnet is in uniform motion towards the coil — Incorrect. The speed is constant, so the emf is steady at a lower value than in the accelerated case.
Option (4) magnet is decelerated away from the coil — Incorrect. The magnet is slowing down, so the rate of change of flux, and the deflection, is decreasing.
NCERT (2026-27):
The Experiments of Faraday and Henry – “… Further, the deflection (and hence current) is found to be larger when the magnet is pushed towards or pulled away from the coil faster.”
Faraday’s Law of Induction – “… The magnitude of the induced emf in a circuit is equal to the time rate of change of magnetic flux through the circuit.”