The primary voltage supplied to a transformer is 8.0 V. The secondary voltage is 12.0 V and the secondary current is 3.0 A. The transformer is 100% efficient.
What is the primary current in the transformer?
2.0 A2.0\text{ A}2.0 A
4.5 A4.5\text{ A}4.5 A
5.0 A5.0\text{ A}5.0 A
8.0 A8.0\text{ A}8.0 A
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.