Science Project Details:

Electromagnets and the number of coils

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Difficulty: Advanced 8
Cost ($): 70
Time required:
1 day to prepare, 1 day for experiment
Availability of materials:
The wires can be purchased at a hardware shop.
Safety concerns:

Basic safety requirements

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Abstract

This experiment was done to investigate the relationship between the number of turns in a coil and the voltage induced in it by a moving magnet.

Hypothesis

The coil that has many turns will have the highest voltage. Thus, the greater the number the turns, the higher the voltage.

Scientific Terms

Electromagnetic induction, magnetic field, magnetic flux, induced voltage

Background

Electromagnetic induction

Electromagnetic induction occurs when a current is induced in a coil by a changing magnetic field. When either the magnet moves in relation to the coil or the coil moves in relation to the magnet, a current will be induced in the coil. However if there is no relative movement between the coil and the magnet, there will not be any current induced in the coil.

The induced voltage in the coil is proportional to the number of turns in the coil and the rate of change of the magnetic flux.

Induced voltage = - Number of coil turn x rate of change of magnetic flux.

Therefore the induced voltage in the coil can be increased by:

  1. increasing the number of turns in the coil,
  2. increasing the speed of relative movement between the coil and the magnet.