Electromagnetic inductionEdexcel International A Level Physics: Mind map

Exam questions on Electromagnetic induction

1. A bar magnet is pushed into a coil of 400 turns that is connected to a sensitive voltmeter. A student observes the voltmeter reading while moving the magnet.
   Explain why an e.m.f. is induced across the coil only while the magnet is moving.2 marks
2. Two coils are wound on the same soft iron core. The primary coil is connected to a battery through a switch. The secondary coil is connected to a sensitive voltmeter.
   The battery is replaced by a low-frequency alternating supply. Explain why a continuous alternating e.m.f. is now induced in the secondary coil.2 marks
3. A flat coil of 250 turns has an area of 4.0 × 10⁻³ m². The plane of the coil is perpendicular to a uniform magnetic field. The flux density of the field is increased steadily from zero to 0.60 T in a time of 0.20 s.
   Calculate the magnitude of the e.m.f. induced in the coil while the flux density is increasing.3 marks