Write any two factors on which internal resistance of a cell depends. The reading on a high resistance voltmeter, when a cell is connected across it, is 2.2 V. When the terminals of the cell are also connected to a resistance of 5 Ω as shown in the circuit, the voltmeter reading drops to 1.8 V. Find the internal resistance of the cell.
CBSE OUTSIDE DELHI - SET 1 2010
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- Nature of electrolyte.
- Temperature of electrolyte.
- Area of electrode.
- Concentration of electrolyte.
- Distance of separation between the electrodes.
Given $\text{E} = 2.2\text{V};\text{R} = 5 \Omega\text{ and }\text{V} = 1.8\text{V}$
$\therefore\text{I} = \frac{\text{V}}{\text{R}} = \frac{1.8}{5} = 0.36$
$\text{V} = \text{E} - \text{Ir}$
$\Rightarrow\text{r} = \frac{\text{E - V }}{\text{I}} = \frac{2.2 - 1.8}{0.36} = \frac{10}{9} = 1.1\Omega$
Alternate Answer
$\text{r} = \bigg(\frac{\text{E - V}}{\text{V}}\bigg)\times\text{R}$
$ = \bigg(\frac{2.2 - 1.8}{1.8}\bigg)\times5$
$ = 1.1\Omega.$
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