Electromagnetic inductionAQA A-Level Physics: Flashcards

What these 12 flashcards ask

State Faraday's law.
Write the equation for Faraday's law.
State Lenz's law.
Which conservation law does Lenz's law express?
When is an emf induced in a coil?
Give three ways to increase the induced emf when moving a magnet into a coil.
State the emf induced in a straight conductor moving at right angles to a field.
Derive ε = Blv.
State the emf induced in a coil rotating uniformly in a field.
When is the emf from a rotating coil a maximum?
When is the emf from a rotating coil zero?
What happens to the peak emf and frequency if the rotation rate is doubled?

Exam questions on Electromagnetic induction

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
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
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

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).