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Electromagnetic induction and generatorsIB MYP Physics: Flashcards

What these 14 flashcards ask

  • What is electromagnetic induction?
  • Name two ways to induce an e.m.f. in a coil.
  • What happens if the magnet is held still in the coil?
  • What happens to the e.m.f. if the direction of movement is reversed?
  • Name three ways to increase the induced e.m.f.
  • What does Lenz's law say?
  • A north pole is pushed into a coil. What pole forms at that end?
  • Why does Lenz's law agree with conservation of energy?
  • What does an a.c. generator do?
  • What are slip rings and brushes for?
  • What is frequency?
  • What is amplitude?
  • What happens if a generator coil turns twice as fast?
  • What is the difference between a.c. and d.c.?

Exam questions on Electromagnetic induction and generators

  1. A student in Lagos connects a coil of wire to a sensitive centre-zero voltmeter and moves a bar magnet into and out of the coil.
    Explain why the voltmeter needle swings the opposite way when the magnet is pulled out of the coil compared with when it is pushed in.2 marks
  2. In a school in Santiago, a bar magnet's north pole is pushed towards one end of a coil of wire. The coil is part of a complete circuit that includes a sensitive ammeter.
    Explain, in terms of energy, why it takes effort to push the magnet into the coil.2 marks
  3. A simple a.c. generator in a school laboratory has a rectangular coil that is turned between the poles of a magnet. The ends of the coil are connected to slip rings and carbon brushes, and the output is displayed on an oscilloscope as a wave that repeats.
    Explain how the generator produces an alternating e.m.f. when the coil is turned.3 marks
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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).