CBSE 2026 · Region 3 · Set 1 · Q13 · 1 mark

Assertion (A) : In a Wheatstone bridge circuit, if we interchange the position of the cell and the galvanometer, the balance condition $\displaystyle \frac{\mathrm{P}}{\mathrm{Q}}=\frac{\mathrm{R}}{\mathrm{S}}$ remains unchanged. Reason (R) : $\displaystyle \frac{\mathrm{P}}{\mathrm{Q}}=\frac{\mathrm{R}}{\mathrm{S}} \Rightarrow \frac{\mathrm{Q}}{\mathrm{S}}=\frac{\mathrm{P}}{\mathrm{R}}$ so balance condition remains same.

CBSE Class 12 Physics past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.