7.2.1

Electromagnetism

Test yourself

The Magnetic Effect of a Current

Any electric current produces a magnetic field.

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Magnetic field lines

  • The magnetic field lines created by current are shown above in the image.
  • The magnetic field lines are circles around a single conducting wire.
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Strength of magnetic field

  • The strength of the field depends on the size of the current and the distance away from the wire.
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Right hand grip

  • The direction of the field lines depends on the direction of the current.
    • Grip the wire with your right hand, with the thumb pointing in the direction of the current.
    • Your fingers curled around the wire will point in the direction of the magnetic field.

Magnetic Field around a Coil of Wire

A solenoid is a loop of wire coiled into a cylindrical (cylinder like) shape. The magnetic field lines for a solenoid are drawn below:

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Inside the coil

  • Inside the coil of wire, the field lines are evenly spaced, parallel, straight lines.
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Outside

  • Outside of the coil of wire, the field lines look like the field lines around a bar magnet, with a clear north and south pole (remember that magnetic field lines around a magnet go from North to South).
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Strong and uniform

  • The magnetic field is strong and uniform. This means that the magnetic field is of the same strength and in the same direction at every point.

Jump to other topics

1Energy

2Electricity

3Particle Model of Matter

4Atoms & Radiation

5Forces

6Waves

7Magnetism

8Astrophysics

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