Sensitivity of a Potentiometer

Introduction:
A potentiometer is an electrical device used to measure an unknown voltage by comparing it with a known voltage. It consists of a long wire of uniform resistance, a jockey sliding over the wire, and a galvanometer connected across the wire.

Definition:
The sensitivity of a potentiometer refers to the ability of the device to detect small changes in voltage. A higher sensitivity means that the potentiometer is capable of accurately measuring smaller voltage differences.

Factors Affecting Sensitivity:
Several factors can affect the sensitivity of a potentiometer, including the length of the potentiometer wire, the e.m.f. of the primary cell, the potential gradient along the wire, and the resistance of the wire.

Explanation:
Among the given options, increasing the length of the potentiometer wire (Option 'A') is the correct answer to increase the sensitivity of the potentiometer. This can be understood through the following points:

1. Principle of Potentiometer:
The principle of a potentiometer is based on the fact that the potential difference across any length of a uniform wire is directly proportional to its length. Therefore, a longer wire will provide a larger range of potential differences to measure.

2. Effect of Wire Length:
By increasing the length of the potentiometer wire, the potential differences that can be measured also increase. This allows for a better resolution and accuracy in measuring small voltage differences.

3. Increased Voltage Range:
With a longer wire, the potentiometer can cover a larger range of voltages. This means that even small changes in voltage can be detected and measured effectively. It enhances the sensitivity of the potentiometer.

4. Higher Resolution:
Increasing the length of the potentiometer wire increases the number of divisions on the scale, which leads to a higher resolution. This allows for more precise measurements and improves the sensitivity of the potentiometer.

5. Limitations:
However, it is important to note that increasing the length of the potentiometer wire also increases the resistance of the wire. This may introduce errors due to the internal resistance of the potentiometer and decrease the overall accuracy of the measurements.

Conclusion:
In conclusion, increasing the length of the potentiometer wire is the correct option to increase the sensitivity of the potentiometer. This allows for a larger range of potential differences, higher resolution, and better accuracy in measuring small voltage differences. However, one must consider the limitations of increased wire length, such as increased wire resistance, which can affect the accuracy of measurements.