An electrical power grid transmits 120 MW120\text{ MW}120 MW of power from a power station to a substation through transmission cables with a total resistance of 8.0 Ω.
Calculate the power lost as heat in the transmission cables if the power is transmitted at a voltage of 240 kV240\text{ kV}240 kV.
Explain, using the relevant formulas, why using a high voltage of 240 kV240\text{ kV}240 kV is preferable to a lower voltage (such as 120 kV120\text{ kV}120 kV) for transmitting electrical power over long distances.
69 exam-style questions on CIE IGCSE Physics 4.2.5 Electrical energy and electrical power. Each one has a worked solution and a mark scheme showing where the marks go.