New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

    Four identical cells, each having an emf of 1.8 V,

    are linked in parallel and connected to an external network made of two resistors of 10 Ω each arranged in parallel. If the potential difference across the output terminals is measured to be 1.5 V by an ideal voltmeter, what is the internal resistance of each cell?
    A 0.6 Ω Correct Answer Incorrect Answer
    B 1.5 Ω Correct Answer Incorrect Answer
    C 3 Ω Correct Answer Incorrect Answer
    D 4 Ω Correct Answer Incorrect Answer

    Solution

    When multiple identical cells are joined in parallel, the net emf remains the same as that of a single cell. Hence,
    Total emf (E) = 1.8 V Let r be the internal resistance of each cell. Since the cells are in parallel, their effective internal resistance is reduced: Now, calculate the combined resistance of the external circuit: Two 10 Ω resistors in parallel: Using Ohm’s law: The potential drop inside the battery system due to internal resistance is:

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