A student is demonstrating electromagnetic induction. A straight copper rod is connected by flexible wires to a sensitive centre-zero galvanometer. The rod is held horizontally and successfully moved vertically up and down in the gap between the north and south poles of a U-shaped magnet. Explain why a reading is observed on the galvanometer only when the rod is moving.
State two changes to the experimental setup or procedure that would increase the maximum deflection of the galvanometer pointer.
After being generated, electricity is stepped up using a transformer before transmission. A step-up transformer has 80 turns on its primary coil and 1200 turns on its secondary coil. The input alternating voltage to the primary coil is 11 000 V11\,000\text{ V}11000 V. Calculate the output voltage from the secondary coil.
Explain two advantages of transmitting electrical energy through transmission lines at very high voltages.
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.