Explain, in terms of charge carriers:
(i) why metals are good conductors of electricity,
(ii) why insulators do not conduct electricity.
The battery of an electric delivery van supplies a current of 80 A80\text{ A}80 A at 110 V110\text{ V}110 V to the motor which drives the vehicle.
(i) State the useful energy change that takes place in the battery when it is operating.
(ii) Calculate the total electrical energy delivered to the motor in 15 minutes15\text{ minutes}15 minutes.
(iii) The motor of the van operates with an efficiency of 85%85\%85%. Calculate the useful power output of the motor.
452 exam-style questions on CIE IGCSE Physics 4.2 Electrical quantities, covering 4.2.1a Positive and negative charge, 4.2.1b Charging by friction and detecting charge, 4.2.1c Electrical conductors and insulators, 4.2.1d Electric fields and electric field patterns, 4.2.2a Electric current, charge and measuring current, 4.2.2b Conduction in metals and the direction of current, 4.2.2c Direct current and alternating current, 4.2.3a Electromotive force, 4.2.3b Potential difference and voltmeters, 4.2.4a Resistance, 4.2.4b Resistance of a metallic wire, 4.2.4c Current–voltage graphs, and 4.2.5 Electrical energy and electrical power. Each one has a worked solution and a mark scheme showing where the marks go.