JAMB Physics 2014 Paper

Concept:Maximum power is delivered by a cell when the load resistance matches the cell's internal resistance.Explanation:For a cell of internal resistance $r$ and external resistance $R$, the power delivered to the external load is given by $P = I^2 R$.Using Ohm's law, $I = \frac{E}{R + r}$, so $P = \frac{E^2 R}{(R + r)^2}$.To find the condition for maximum power, differentiate $P$ with respect to $R$ and set it to zero: $\frac{dP}{dR} = 0$.This yields $R = r$.Therefore, the maximum power transfer occurs when the external resistance equals the internal resistance of the cell.Answer:B. The same as the internal resistance of the cell