Question

Lenz’s law is a consequence of the law of conservation of ………..
A) Charge
B) Mass
C) Energy
D) Momentum

Answer 1

Hint: Lenz’s law is used to determine the direction of the induced current by a change in magnetic field. This direction of the induced current always opposes the direction of the magnetic field which produced it.

Complete step by step answer:
Lenz’s law states that the direction of an induced current by a changing magnetic field is such that the magnetic field created by the induced current opposes that change responsible for its production. This means, a change in magnetic field (B1) produces an induced current and the induce current also generates some magnetic field (B2) which is different from the initial magnetic field (B1). Now, the generated magnetic field (B2) by the induced current opposes the initial changing magnetic field (B1). Consider a magnet and a coil, such that the magnet is approaching towards the coil. When the north pole of a magnet is moved towards a coil, the face of the coil near to the magnet behaves like a north pole and tries to repel the approaching North Pole. To do this, the coil generates an anticlockwise current in itself. Here, we can see that electrical energy is not generated just by moving the magnet towards the coil. There is an opposite for the change in flux. Hence we can say that Lenz’s law is a consequence of conservation of energy. Thus, the right answer is Option C; Lenz’s law is a consequence of law of conservation of energy.

Note:We can use Fleming’s right hand rule to find the direction of induced current and it is based on Lenz’s law. Faraday’s law tells us the magnitude of the Electromotive force and the current is induced because of the change in magnetic field whereas Lenz’s law tells us the direction of the induced current flow and the direction is the opposite of the initial magnetic field. These two laws are different. Do not confuse Lenz’s law with Faraday’s law.