Potentiometer Driver EMF – Rankers Physics

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

Assertion (A): The emf of the driver cell in the potentiometer experiment should be greater than the e.m.f. of the cell to be determined. Reason (R): The fall of potential drop across the potentiometer wire should be less than the e.m.f. of the cell to be determined.
(1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
(2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(3) (A) is true but (R) is false
(4) Both (A) and (R) are false

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 to function, the driver cell's EMF must exceed the unknown EMF to ensure a balancing point can be found. The potential drop across the entire potentiometer wire must be greater than the unknown EMF. Reason (R) states the opposite, making it false.

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