In a potentiometer experiment, for measuring internal resistance of a cell, the balance point has been obtained on the fourth wire. The balance point can be shifted to fifth wire bya)increasing the current due to auxiliary batteryb)Putting a shunt resistance in parallel with the cell.c)decreasing the current due to auxiliary batteryd)putting a suitable resistance in series with the cell.Correct answer is option 'C'. Can you explain this answer?

Question

Answer

Understanding the Potentiometer Experiment
In a potentiometer experiment aimed at measuring the internal resistance of a cell, the balance point indicates where the potential difference across the wire matches that of the cell being measured. When the balance point is observed on the fourth wire, adjustments can be made to shift it to the fifth wire.
Effect of Current on Balance Point
- The balance point is directly related to the current flowing through the circuit.
- An increase in current will raise the voltage drop across the potentiometer wire, potentially moving the balance point farther away, rather than towards the fifth wire.
Options Analysis
- Option A: Increasing the current due to the auxiliary battery
This would likely move the balance point further along the wire, making it harder to achieve balance at the fifth wire.
- Option B: Putting a shunt resistance in parallel with the cell
This could alter the effective resistance, but it does not necessarily shift the balance point in the desired direction.
- Option C: Decreasing the current due to the auxiliary battery
Lowering the current decreases the voltage drop across the potentiometer wire, allowing the balance point to shift backward toward the fifth wire, making this option correct.
- Option D: Putting a suitable resistance in series with the cell
This would increase the total resistance in the circuit but would not effectively help in shifting the balance point to the fifth wire.
Conclusion
By decreasing the current from the auxiliary battery, the voltage drop across the potentiometer wire is reduced, thus allowing the balance point to shift from the fourth wire to the fifth wire. This approach effectively facilitates the measurement of the internal resistance of the cell in a potentiometer setup.

Answer

If the current due to the auxillary battery is decreased, the potential gradient will be decreases, so the balancing length increases.Thus null point will move to fifth wire.

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