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 potentiometer measures the electromotive force (e.m.f.) of a cell using a null deflection method.
At the balance point, no current flows through the galvanometer, so no current is drawn from the cell being measured.
This allows it to measure the true open-circuit potential difference accurately.