Question

Assertion :
A uniformly charged disc has a pin hole at its centre. The electric field at the centre of the disc is zero.

Reason :
Disc can be supposed to be made up of many rings. also electric field at the centre of uniformly charged ring is zero.

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

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.

The electric field due to disc is superposition of electric fields due to its constituent ring as given in statement-2.

We know that electric field at the center of the ring is zero, hence by superposition electric field at the centre of disc is zero.

Hence, statement 1 is true, statement-2 is also true and statement-2 is a correct explanation of statement-1.

Therefore, option $\left(a\right)$ is the correct answer.