Electrical power is transmitted over long distances through overhead transmission cables. Why is a very high voltage used to transmit this electrical energy?
It increases the current flowing through the cables, allowing more power to be delivered.
It reduces the current for a given power, which decreases the energy wasted as thermal energy in the cables.
It increases the resistance of the cables, which prevents them from overheating.
It allows the electrons to travel faster, ensuring the electricity reaches consumers more quickly.
275 exam-style questions on CIE IGCSE Physics 4.5 Electromagnetic effects, covering 4.5.1a Electromagnetic induction, 4.5.1b Direction of an induced e.m.f., 4.5.2 The a.c. generator, 4.5.3a Magnetic effect of a current and its applications, 4.5.3b Strength and direction of the field around wires and solenoids, 4.5.4a Force on a current-carrying conductor, 4.5.4b Force on beams of charged particles, 4.5.5 The d.c. motor, 4.5.6a Construction and operation of a transformer, 4.5.6b Turns ratio and current in a transformer, and 4.5.6c High-voltage transmission of electricity. Each one has a worked solution and a mark scheme showing where the marks go.