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Question

Difficulty: EasyElectromagnetism and Induction

What is required to induce an electric current in a stationary coil of wire using a magnet?

  1. A
    A constant, stationary magnetic field held next to the coil
  2. Relative motion between the magnetic field and the coilAnswer
  3. C
    An electrostatic charge stored inside an insulating dielectric
  4. D
    A fixed potential difference that prevents magnetic line movement

Answer

Relative motion between the magnetic field and the coil is required to induce an electric current.
According to the principle of electromagnetic induction, an electric current is generated in a conductor when magnetic lines of force cut across the wire. This requires relative motion between the magnetic field and the coil, creating a changing magnetic flux that produces an electromotive force (voltage).

Step-by-Step Solution

1
Identify the fundamental principle of electromagnetic induction defined by Faraday's Law.
An electromotive force (EMF) is induced in a wire loop only when the loop experiences a changing magnetic flux.
Stationary magnetic fields do not cut across stationary conductors, producing zero induced voltage.
2
Determine the physical condition necessary to produce this change in magnetic flux.
There must be relative motion between the magnet and the coil so that magnetic lines of force cut across the turns of wire.
Moving the magnet relative to the coil causes the magnetic flux density through the coil to vary with time, driving electron movement.

Key Concept

Faraday's Law of Electromagnetic Induction
Estimated Time:45s
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Topics

Electromagnetism and Induction

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