Abhi koi question add nahi kiya. PYQ Bank se questions add karein.
PYQ Bank ›
Class 12 › Physics › Current Electricity
CBSE2026Class Class 12 · Physics1 Marks · Long✅ Verified
Assertion (A): In a Wheatstone bridge circuit, if we interchange the position of the cell and the galvanometer, the balance condition $\dfrac{P}{Q}=\dfrac{R}{S}$ remains unchanged.
Reason (R): $\dfrac{P}{Q}=\dfrac{R}{S} \Rightarrow \dfrac{Q}{S}=\dfrac{P}{R}$, so the balance condition remains the same.
(A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
(C) Assertion (A) is true, but Reason (R) is false.
(D) Assertion (A) is false, but Reason (R) is true.
✅ Answer & Solution
The assertion is true: interchanging the cell and galvanometer in a balanced Wheatstone bridge does not disturb the balance condition. However, the reason as stated is incorrect. From $\frac{P}{Q}=\frac{R}{S}$, cross-multiplying gives $PS=QR$, which rearranges to $\frac{P}{R}=\frac{Q}{S}$, not $\frac{Q}{S}=\frac{P}{R}$ being equivalent in the manner stated (the algebra written in R is not the correct justification). Hence Assertion is true but Reason is false. The correct option is (C).
