A copper coil is placed with its axis horizontally from left to right. The \(N\) pole of a bar magnet is moved towards the coil parallel to its axis. The induced current produces a magnetic field in the coil. In this context, identify the correct statements among the following.
A. If the magnet is moved towards the coil, the coil tries to move away as the magnetic pole induced in the coil will be \(N\) pole.
B. If the speed of the magnet is increased, then the coil moves away faster from the magnet.
C. If the pole of the magnet is reversed such that the \(S\) pole is moved towards the coil, then the coil is moved away from the magnet.
D. If the magnet is kept static, then no movement in the coil is observed.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → A, B, C and D
By Lenz’s law, the induced current opposes the change that produces it, so an approaching pole meets a like pole on the near face of the coil and is repelled.
(A) If the magnet is moved towards the coil, the coil tries to move away as the magnetic pole induced in the coil will be \( N \) pole. — Correct. Like poles repel.
(B) If the speed of the magnet is increased, then the coil moves away faster from the magnet. — Correct. A faster change of flux gives a larger emf, current and force.
(C) If the pole of the magnet is reversed such that the \( S \) pole is moved towards the coil, then the coil is moved away from the magnet. — Correct. The near face becomes an S pole, again a like pole.
(D) If the magnet is kept static, then no movement in the coil is observed. — Correct. No change of flux, so no induced current.
NCERT (2026-27):
Lenz’s Law and Conservation of Energy – “… The statement of the law is: The polarity of induced emf is such that it tends to produce a current which opposes the change in magnetic flux that produced it.”
Lenz’s Law and Conservation of Energy – “… In Fig. 6.1, we see that the North-pole of a bar magnet is being pushed towards the closed coil. As the North-pole of the bar magnet moves towards the coil, the magnetic flux through the coil increases. Hence current is induced in the coil in such a direction that it opposes the increase in flux. … Note that magnetic moment associated with this current has North polarity towards the North-pole of the approaching magnet.”
Lenz’s Law and Conservation of Energy – “… In this situation, the bar magnet experiences a repulsive force due to the induced current.”