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Physics - Current Electricity Question with Solution | TestHub

PhysicsCurrent ElectricityElectrical instrumentMedium2 minQB

PhysicsMediumnumerical

In the shown potentiometer arrangement the wire PQ has a resistance of $5Ω$ and the driver cell has an emf of 2V. If a balance point is obtained at 0.6m along PQ, what is the value of resistance $R ($ in $Ω)? ($ Length $PQ = 1 m)$

Answer:

995.00

Solution:

The balance point fixes the potential gradient: 6 mV across 0.6 m, i.e. 10 mV/m, so the full 1 m wire ( $5 Ω$ ) drops 10 mV.

Wire current $I = \frac{10 mV}{5 Ω} = 2$ mA.

The 2 V driver cell feeds R and the wire in series: $R + 5 = \frac{2}{2 mA} = 1000 Ω$ , so $R = 995 Ω$ .

Stream:JEESubject:PhysicsTopic:Current ElectricitySubtopic:Electrical instrument

⏱ 2mℹ️ Source: QB

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