The reading on a high resistance voltmeter, when a cell is connected across it, is 2.2 V. When a 5 `Omega` resistance is connected across the terminals of the cell in parallel with the voltmeter, the reading is 1.8 V. Determine the internal resistance of the cell.

Explanation

Here reading of voltmeter when connected directly to a cell = emf of cell `epsi` =2.2 V. External resistance R=5`Omega` and terminal voltage V = 1.8 V.
` therefore `Internal resistance of cell `r = (epsi - V)/(V) .R = (2.2 - 1.8)/(1.8) xx 5 = 1.1 Omega`