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Question
A cell of e.m.f. E and internal resistance r is used to send current I in an external resistance R. Write expressions for (i) the current drawn from the cell,
(ii) the terminal voltage V of the cell, and
(iii) the voltage drop across the internal resistance. How are E and V related?
Solution
Total resistance of circuit = R + r
(i) The current drawn from the cell, I + `"E"/("R + r")`
(ii) The terminal voltage of the cell, V = IR
(iii) The voltage drop across the internal resistance = IR
E and V are related as E = V + IR.
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