To measure the internal resistance of a cell

To measure the internal resistance of a cell

A high-resistance voltmeter is connected to the cell terminals and the reading noted.

This will give the e.m.f. of the cell. A 1 n resistor is now connected to the cell terminals and the voltmeter reading taken again (Fig. 35.10). Further readings are taken using 2, 3, 4, etc., ohms, and the results are recorded in the table shown.

Note. Consistent results must not be expected if the cell polarizes during the experiment.
The method is unsuitable for cells of very low internal resistance such as lead
cells.