Electromagnetic inductionEdexcel A-Level Physics: Flashcards
What these 13 flashcards ask
- What is electromagnetic induction?
- Why is no e.m.f. induced when a magnet is held stationary inside a coil?
- State three ways to increase the e.m.f. induced when a magnet moves into a coil.
- How can an e.m.f. be induced in a coil with no moving magnet?
- State Faraday's law.
- Write Faraday's law as an equation.
- What does the minus sign in Faraday's law mean?
- State Lenz's law.
- How is Lenz's law linked to conservation of energy?
- What is the effect of a soft iron core between a primary and a secondary coil?
- A magnet's north pole is withdrawn from a coil. What pole forms at the near end of the coil?
- What is the unit of flux linkage?
- What happens to the induced e.m.f. if the time taken for a change in flux linkage is halved?
Exam questions on Electromagnetic induction
- A bar magnet is pushed, north pole first, into one end of a long solenoid that is connected to a sensitive centre-zero voltmeter.Explain, using the principle of conservation of energy, why the induced current must produce a magnetic field that opposes the movement of the magnet.2 marks
- A flat coil of 400 turns and cross-sectional area 2.5 × 10⁻³ m² is placed with its plane perpendicular to a uniform magnetic field. The flux density falls uniformly from 0.80 T to 0.20 T in 0.30 s.The same fall in flux density, from 0.80 T to 0.20 T, now takes 0.60 s instead of 0.30 s. Calculate the new average induced e.m.f. and explain your answer.2 marks
- A flat rectangular coil of 50 turns and area 6.0 × 10⁻³ m² is held with its plane perpendicular to a uniform magnetic field of flux density 0.40 T. It is rotated through 90° about an axis lying in its plane, in a time of 0.050 s, so that its plane finishes parallel to the field lines.Calculate the initial flux linkage of the coil and the average e.m.f. induced in it during the rotation.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).