Measuring Devices ( Galvanometer, Voltmeter and Ammeter & Meter Bridge ): Practice Problem & Solution
In a potentiometer circuit a cell of EMF $1.5\text{ V}$ gives balance point at $36\text{ cm}$ length of wire. If another cell of EMF $2.5\text{ V}$ replaces the first cell, then at what length of the wire, the balance point occurs? (2021)
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:
For a potentiometer, the EMF is directly proportional to the balancing length: $\frac{E_1}{E_2} = \frac{l_1}{l_2}$.nSubstitute the given values: $\frac{1.5}{2.5} = \frac{36}{l_2}$.n$l_2 = 36 \times \frac{2.5}{1.5} = 36 \times \frac{5}{3} = 60\text{ cm}$.
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