Moderate

Alternating emf is produced by rotating a coil of wire in:

Correct answer: B. Magnetic field

  • A. Electric field
  • B. Magnetic field
  • C. Conservative field
  • D. Gravitational field

Explanation

An alternating electromotive force (emf) is generated by rotating a coil of wire within a magnetic field. This setup induces a changing magnetic flux within the coil, as governed by Faraday's law of electromagnetic induction. The resultant alternating emf causes an alternating current (AC) when the coil is connected to a circuit. This principle forms the basis of operation for most AC generators or alternators.

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About Electromagnetic Induction

Changing magnetic flux induces an emf according to Faraday's law, while Lenz's law gives the direction that opposes the change producing it. Transformers apply induction between coils to step alternating voltage up or down, with turns ratio, current transformation and energy losses determining practical operation.

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