GATE 2025 EE – Question 59
In the Wheatstone bridge shown below, the sensitivity of the bridge in terms of change in balancing voltage $E$ for unit change in the resistance $R$, in mV/Ω, is ______________ (round off to two decimal places).
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Correct answer: 1.95 to 1.97
Explanation
With the battery $V=10$ V, the detector voltage is $E=V\left[\dfrac{S}{R+S}-\dfrac{Q}{P+Q}\right]$. The bridge is balanced ($50/5000=10/1000$). $\left|\dfrac{dE}{dR}\right|=\dfrac{VS}{(R+S)^2}=\dfrac{10\times5000}{5050^2}=1.96\times10^{-3}$ V/Ω $=1.96$ mV/Ω.