JAMB Physics 2018 Paper

Concept:Energy loss in transmission lines is caused by heat produced when current flows through the wires, and this loss is reduced by transmitting at a higher voltage.Explanation:The power transmitted is given by $P = VI$, where $V$ is the voltage and $I$ is the current.For a fixed amount of power, increasing the voltage reduces the current because $I = \frac{P}{V}$.Transmission lines have resistance $R$, so the power lost along them is $P_{\text{loss}} = I^2R$.This lost power is converted into heat energy in the conductors, which is the main source of energy loss.Using a low voltage would force a very large current to flow, leading to a massive $I^2R$ heat loss.By stepping up the voltage, the current becomes smaller, so the heat dissipated in the line is greatly reduced.Hence, the energy loss during transmission is primarily due to heat dissipation in the cables.Answer:A. Heat dissipation