Measuring Devices ( Galvanometer, Voltmeter and Ammeter & Meter Bridge ): Practice Problem & Solution

Solution Explained:

To solve this problem, we apply the core principles of Measuring Devices ( Galvanometer, Voltmeter and Ammeter & Meter Bridge ). Understanding the underlying formula is key to arriving at the correct answer below:

A longer potentiometer wire, for a given driver cell, results in a smaller potential gradient \( k = V/L \). A smaller potential gradient means that even a small change in potential corresponds to a significant change in balancing length, increasing the sensitivity and accuracy of the measurement. Thus, both (A) and (R) are true, and (R) correctly explains (A).