Question

Draw circuit diagram of Wheatstone’s bridge. Which are its conjugate arms?

Hint:

Wheatstone’s bridge is widely used to measure unknown resistance accurately.

Answer 1

Step 1: Wheatstone’s bridge principle.
It is based on the principle of null deflection, where no current flows through the galvanometer if the bridge is balanced.
Step 2: Circuit diagram.
The bridge has four resistors $P$, $Q$, $R$, and $S$ connected in a quadrilateral. A galvanometer is connected between two opposite corners, and a battery between the remaining two corners. \[ \text{Balanced condition: } \frac{P}{Q} = \frac{R}{S} \]
Step 3: Conjugate arms.
Conjugate arms are opposite pairs: (P, Q) with (R, S). Specifically, AB and CD are conjugate arms; AD and BC are also conjugate arms.
Step 4: Conclusion.
Wheatstone’s bridge works on balancing ratios of conjugate arms.