Electromagnetic inductionAQA A-Level Physics: Mind map

Exam questions on Electromagnetic induction

1. In a laboratory demonstration, the north pole of a bar magnet is pushed steadily towards, and into, a coil of wire that is connected to a sensitive voltmeter.
   Explain, using Lenz's law, why work must be done to push the magnet into the coil when the coil is part of a complete circuit.2 marks
2. A coil of 300 turns and cross-sectional area 4.0 × 10⁻³ m² is placed with its plane perpendicular to a uniform magnetic field. The flux density of the field decreases uniformly from 0.80 T to 0.20 T in 0.15 s.
   Explain why the induced emf has a constant value during the 0.15 s.2 marks
3. An aircraft with a horizontal metal wing of span 36 m flies horizontally at a constant speed of 250 m s⁻¹. The vertical component of the Earth's magnetic flux density where it is flying is 4.5 × 10⁻⁵ T.
   Show that the emf induced between the wing tips is Blv, where l is the span of the wing and v is the speed.3 marks