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Question
Plot a graph showing variation of voltage vs the current drawn from the cell. How can one get information from this plot about the emf of the cell and its internal resistance?
Solution
Variation of voltage vs the current drawn from the cell shown below:
\[V = E - Ir\]
\[At, I = 0\]
\[V = E\]
\[\text { and }\]
\[r = \frac{E - V}{I}\]
The slope of the graph give the value of internal resistance and intercept on Y-axis gives the emf of the cell.
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