Question

Assertion (A): In a Wheatstone bridge circuit, if we interchange the position of the cell and the galvanometer, the balance condition `P/Q = R/S` remains unchanged.

Reason (R): `P/Q = R/S = Q/S = P/R`, so balance condition remains same.

Options

• Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

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

• Assertion (A) is true, but Reason (R) is false.

• Both Assertion (A) and Reason (R) are false.

Answer 1

Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

Explanation:

In a Wheatstone bridge, the condition for balance is:

`P/Q = R/S`

At the balanced condition:

• No current flows through the galvanometer.
• The potential difference across the galvanometer is zero.

Analyze Assertion

Since no current passes through the galvanometer at balance, exchanging the cell and the galvanometer does not disturb the balance condition.

Therefore, Assertion (A) is true.

Analyze Reason

From the balance condition:

`P/Q = R/S`

PS = QR

`Q/S = P/R`

This symmetry shows that interchanging the cell and galvanometer does not change the balance condition.

Hence, Reason (R) is true and correctly explains the Assertion.