Physics 2014 JAMB Past Questions - Question 36: The maximum power transfer occurs in cell when the external resistance is

Correct Answer

A

Explanation

the maximum power obtained when the external resistance, R is equal to the internal resistance, r of the cell.The maximum power transfer theorem states that the maximum power is transferred from a source (like a battery or a cell) to a load (external resistance) when the resistance of the load is equal to the internal resistance of the source. In other words, for a cell with internal resistance, the maximum power is transferred to the external load when the resistance of the load matches the internal resistance of the cell.

Mathematically, if the internal resistance of the cell is "Ri" and the load resistance is "Rl," then the maximum power is transferred when Rl = Ri. When the load resistance equals the internal resistance, the maximum power is dissipated in the load. This is known as the "load matching" condition.

The formula for the power dissipated in the load (P) is given by:

P = (V^2 * Rl) / (Ri + Rl)

Where:
- P is the power dissipated in the load.
- V is the voltage of the cell.
- Ri is the internal resistance of the cell.
- Rl is the resistance of the external load.

To maximize power transfer, you adjust the load resistance (Rl) to match the internal resistance (Ri). This is a theoretical concept, and in practical situations, it may not always be possible to perfectly match these resistances, but the goal is to get them as close as possible for maximum power transfer.