A wheatstone bridge is used to determine the value of unknown resistance X by adjusting the variable resistance Y as shown in the figure. For the most precise measurement of X, the resistance P and Q (a) Should be approximately equal to 2X (b) Should be approximately equal and are small (c) Should be very large and unequal (d) Do not play any significant role

Answer: (b). The bridge is most sensitive when all four arm resistances are of the same order. With P ≈ Q, balance gives X ≈ Y directly, and small P, Q allow larger galvanometer current near balance, so a small imbalance is easily detected. So the answer is (b) approximately equal and small.

A wheatstone bridge is used to determine the value of unknown… | NEET 2022 (Phase 1)

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Wheatstone Bridge & Metre Bridge

A wheatstone bridge is used to determine the value of unknown resistance X by adjusting the variable resistance Y as shown in the figure. For the most precise measurement of X, the resistance P and Q

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Answer: (b)

The bridge is most sensitive when all four arm resistances are of the same order.
With $P \approx Q$ , balance gives $X \approx Y$ directly, and small $P, Q$ allow larger galvanometer current near balance, so a small imbalance is easily detected.
So the answer is (b) approximately equal and small.

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