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Class 12 › Physics › Current Electricity
CBSE2019Class Class 12 · Physics2 Marks · Short✅ Verified
A cell of emf $E$ is connected across an external resistance $R$. When current $I$ is drawn from the cell, the potential difference across the electrodes drops to $V$. Write the expression for the internal resistance $r$ of the cell.
✅ Answer & Solution
Using terminal voltage equation $V = E - Ir$, rearranging:
$$r = \frac{E - V}{I}$$
