Electrical power is transmitted across the national grid at 275 kV275\text{ kV}275 kV and transformed down to 230 V before being supplied to consumers.
Which statement is correct?
A 275 kV275\text{ kV}275 kV transmission cable requires less insulation to prevent electrical breakdown than a 230 V230\text{ V}230 V consumer cable.
Birds sitting on a single high-voltage transmission line are electrocuted because of the large current carried by the wire.
The current in the transmission cables is greater than the total current delivered to all the consumers.
Transmitting power at 275 kV275\text{ kV}275 kV rather than at 230 V230\text{ V}230 V reduces the current in the cables, which decreases the proportion of energy lost as heat.
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.