Physics – 4.3.3 Action and use of circuit components | e-Consult

To calculate the internal resistance, we can use the formula: r = V / I, where 'r' is the internal resistance, 'V' is the potential difference across the cell, and 'I' is the current.

For Cell 1: r₁ = 1.5 V / I. Since the current is the same through both cells, we can substitute the value of 'I' from Cell 1's calculation into Cell 2's calculation.

For Cell 2: r₂ = 1.0 V / I.

The internal resistance of Cell 1 is 1.5V / I. The internal resistance of Cell 2 is 1.0V / I. The internal resistance is directly proportional to the potential difference and inversely proportional to the current. Therefore, a lower potential difference across a cell indicates a higher internal resistance for a constant current. This is because a higher internal resistance means that more of the potential difference is 'lost' within the cell itself, leaving less potential difference available to overcome the external resistance in the circuit.