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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?
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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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