A cell of emf E and internal resistance r is connected across an external resistance R. Plot a graph showing the variation of P.D. across R, verses R.
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When the cell of emf E and internal resistance r is connected across an external resistance R, the relationship between the voltage across R is given by
$\text{V}=\frac{\text{E}}{\big[1+\big(\frac{\text{r}}{\text{R}}\big)\big]}$
From the above relation,
Now, as $\text{R}=0\Rightarrow\ \text{V}=0\ \&\ \text{R}=\infty\Rightarrow\ \text{V}=\text{E}.$ So, this variation is shown in the figure given below.
$\text{V}=\frac{\text{E}}{\big[1+\big(\frac{\text{r}}{\text{R}}\big)\big]}$
From the above relation,
Now, as $\text{R}=0\Rightarrow\ \text{V}=0\ \&\ \text{R}=\infty\Rightarrow\ \text{V}=\text{E}.$ So, this variation is shown in the figure given below.
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