A resistance R is connected across a cell of emf `epsilon` and internal resistance r. A potentiometer now measures the potential difference between the terminals of the cell is V. Write the expression for r in terms of `epsilon`, V and R`.
Text Solution
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`epsilon = I (R + r) and V = IR` `:. epsilon/V = (R + r)/R = 1 + r/R` or `r/R = (epsilon/V - 1) or r = (epsilon/V - 1)R`
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