Question

The Lenz's law gives?

• A. the direction of the induced current
• B. the magnitude of the induced emf
• C. both the magnitude and direction of the induced current
• D. the magnitude of the induced current

Answer 1

The correct option is A

the direction of the induced current

Explanation for the correct option:

Option (A): the direction of the induced current

1. Lenz's law is known as a law that basically states that the current induced in the circuit because of a change in the magnetic field is directed to oppose the change in the flux, which exerts a mechanical force that opposes the motion.
2. Lenz's law can be given by an equation : $$\epsilon =-\frac{\mathrm{\partial }{\varnothing }_B}{\mathrm{\partial }t}$$
3. The given equation basically indicates that the induced electromotive force $\mathrm{\epsilon }$ and the rate of magnetic flux have opposite signs.
4. Which refers to the direction of the back EMF of an induced field that opposes the changing current.
5. Thus Lenz’s law generally helps us to give the direction of the induced current.

Explanation for the incorrect option:

Option (B): the magnitude of the induced emf:

1. According to the Faradays law of induction, the magnitude of the induced EMF is defined as the product of the number of turns of the winding and the rate of change of flux linkage in it.
2. Lenz's law basically helps us to give us the direction of the induced current and not about the magnitude of the induced emf.
3. Hence, the given option does not coincide with the correct concept.

Option (C): both the magnitude and direction of the induced current

1. The magnitude of the induced current generally depends on the rate of change of magnetic flux or the rate of cutting of the magnetic field lines.
2. Lenz’s law generally helps us to give the direction of the induced current and not the magnitude of the induced emf.
3. The magnitude and direction of the induced current can't be explained with the help of Lenz's law.
4. Thus, the given option is the incorrect one.

Option (D): the magnitude of the induced current

1. Lenz's law helps us to give us the direction of the induced current and does not explain the magnitude of the induced current.
2. Hence, the given option does not coincide with the correct concept.

Hence, option A is correct.