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GATE 2025 IN – Question 61

Measurements · Electrical bridges · 2 marks · Numerical answer

The galvanometer G in the shown circuit has internal resistance 100 Ω. Its current $I_G$ is ______ μA (rounded to the nearest integer).

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Correct answer: 9 to 9

Explanation

With the galvanometer removed, the left midpoint is $4(1010/2010)$ V and the right midpoint is 2 V.

Hence $V_{th}=0.00995025$ V, left positive.

With the supply shorted, $R_{th}=(1000\parallel1010)+(1000\parallel1000)=1002.4876\ \Omega$.

Therefore $I_G=V_{th}/(R_{th}+100)=9.0253\ldots\ \mu\mathrm A$.

In the shown arrow direction, the answer is **9 μA**.