A transformer has 600 turns on the primary coil and 30 turns on the secondary coil. The input voltage is 240 V.
Calculate the output voltage.
The current in the primary coil is 150 mA. The transformer is 100% efficient.
Calculate the output current.
A straight, loose horizontal wire is suspended between two supports in a magnetic field. The magnetic field points horizontally from North to South. The wire is oriented from West to East. When a direct current is passed through the wire from West to East, the wire is observed to deflect upwards.
State and explain the movement of the wire if the power supply connections are reversed so that the current flows from East to West.
State and explain what happens to the wire if the current direction is reversed and at the same time the magnetic poles are swapped (reversing the magnetic field direction).
A split-ring commutator is an important feature of a d.c. motor. Explain how the split-ring commutator ensures that the motor coil rotates continuously in one direction.
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.