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GATE 2026 EE – Question 57

Electrical and Electronic Measurements · Bridges and Potentiometers · 2 marks · Numerical answer

The resistance values of the Wheatstone bridge shown are: $P=2000\ \Omega$, $Q=500\ \Omega$, $R=3000\ \Omega$. The battery voltage $E=50$ V. The battery has an internal resistance of 1 Ω and the Galvanometer (G) has a resistance of 50 Ω.

The value of the resistance $S$ for balanced condition is ____________ Ω.

(Answer in integer)

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Correct answer: 750

Explanation

At balance the galvanometer carries no current, so $\dfrac PQ=\dfrac RS$ and $S=\dfrac{RQ}{P}=\dfrac{3000\times500}{2000}=750\ \Omega$. The battery and galvanometer resistances do not affect the balance condition.