Question

According to Lenz's law of electromagnetic induction

• A. The induced e.m.f. is not in the direction opposing the change in magnetic flux
• B. The relative motion between the coil and magnet produces a change in magnetic flux
• C. Only the magnet should be moved towards coil
• D. Only the coil should be moved towards magnet

Answer 1

The correct option is B

The relative motion between the coil and magnet produces a change in magnetic flux

The explanation for the correct option:

1. According to the Lenz law, the current induced in a circuit due to a change in a magnetic field is directed to oppose the change in the flux to exert a magnetic force which opposes the motion.
2. According to Lenz's law of electromagnetic induction, the relative motion between the coil and the magnet produces a change in the magnetic flux in the coil and the induced EMF is always in such a direction that it opposes the change in the flux.
3. $\epsilon =-N\frac{\partial {\varphi }_B}{\partial t}$ [Where, $\epsilon$ is induced EMF, $N$ is the number of turns, $\partial {\varphi }_B$ is change in magnetic flux, $\partial t$ is change in time.]

Hence, option$\left(B\right)$ is correct.