Question

Lenz law is consistent with conservation of:
A. Energy
B. Mass
C. Charge
D. Momentum

Answer 1

Hint: Lenz's law states that the direction of the induced current in the conductor in such a way that the magnetic field produced by the conductor opposes the change in magnetic field. Using Lenz law, we can find the direction of the electric current. Use Lenz's statement to find that for conservation of which parameter the Lenz remains consistent.

Complete step-by-step answer:
We need to understand Lenz's law first. Lenz's law states that,
“The direction of electric current induced in the conductor due to changing magnetic field is such that the initial changing magnetic field is opposed by the magnetic field created due to induced current.”
Lenz's formula is given by,
$\epsilon = -N \dfrac {\partial {\phi}_{B}}{\partial t}$
Where, $\epsilon$ is the electromotive force generated
              ${\phi}_{B}$ is the change in magnetic field
              N is the number of loops
Kinetic energy is generated due to the current loop through the magnetic field. Now, some electrical energy has to be generated too. But, for the generation of electric energy, total energy of the system has to remain constant. This is due to conservation of energy.
Hence, Lenz law is consistent with conservation of energy.

So, the correct answer is “Option A”.

Note: Students must remember that the negative sign in Lenz’s formula shows that the magnetic field produced due to induced current opposes the change in magnetic field. There are various applications of Lenz law. Few of them are mentioned below:
1. Card readers
2. Metal detectors
3. Microphones
4. Electromagnetic brakes
To find the magnitude of the electromotive force in a current loop, we use Faraday's law. But, to find the direction of the electromotive force we have to depend on Lenz's law.