Question

Assertion (A): It is difficult to move a magnet into a coil of large number of turns when the circuit of the coil is closed.
Reason (R): The direction of induced current in a coil with its circuit closed, due to motion of a magnet, is such that it opposes the cause.

• A. Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
• B. Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
• C. Assertion (A) is true, but Reason (R) is false.
• D. Assertion (A) is false and Reason (R) is also false.

Hint:

Lenz's Law states that the direction of the induced current is always such that it opposes the change causing it.

Answer 1

The Correct Option is A

In this problem, we are given an assertion and a reason related to electromagnetic induction. Let's analyze them:

Assertion (A): It is difficult to move a magnet into a coil of large number of turns when the circuit of the coil is closed.

Reason (R): The direction of induced current in a coil with its circuit closed, due to motion of a magnet, is such that it opposes the cause.

First, understand the phenomenon referred to in both the assertion and the reason, which is explained by Lenz's Law. According to Lenz's Law, the direction of induced current is such that it opposes the change that produced it. This is an application of the conservation of energy.

When a magnet is moved into a coil (especially one with many turns), and the circuit is closed, an induced current is generated due to the change in magnetic flux. This current creates its own magnetic field that opposes the movement of the magnet. Hence, more effort is required to move the magnet into the coil than if the coil circuit were open. This explains why the assertion is true.

The reason correctly states that the induced current's direction opposes the cause of its creation (the movement of the magnet). Therefore, the assertion and reason are both true, and the reason provides the correct explanation for the assertion.

Based on this analysis, the correct option is:
Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).