Physics · Current Electricity

Option A is correct: Doubling the length of the potentiometer wire enhances the accuracy in determining the null point. The longer wire provides a greater range for the sliding contact (jockey) to move, allowing for more precise measurement and better resolution. This makes it easier to detect the exact point where the potential difference is zero.

Options B, C, and D are incorrect: Increasing the length of the wire does not decrease or leave the accuracy unchanged, nor does it unpredictably change. The increased length consistently improves measurement precision, making these options inaccurate.

A potentiometer is a device used to measure potential difference (voltage) by comparing it with a known voltage. It consists of a uniform resistance wire, a galvanometer, and a sliding contact called the "jockey." The null point is the position on the wire where there is no potential difference between the two ends.

When the length of the potentiometer wire is doubled, the overall length of the wire increases. This allows for a finer resolution and more precise measurements. The increased length provides a larger range for the sliding contact to be adjusted, making it easier to find the exact null point. Therefore, the accuracy in determining the null point is increased.

This option is incorrect because increasing the length of the wire actually improves the accuracy, not decreases it. A longer wire allows for finer measurement increments.

This is incorrect because the accuracy in determining the null point improves with the increased length of the potentiometer wire, contrary to the suggestion that it remains constant.

This option is incorrect because doubling the length of the wire consistently results in increased accuracy due to finer resolution, rather than it varying unpredictably.