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Although electric fields create forces on charged objects, magnetic fields are more common in particle accelerators.

Magnetic fields are usually visualized using iron filings but are drawn as lines with arrows pointing from north to south poles:

A magnetic field exists around moving charges such as a wire carrying electrons vertically upwards.

The direction of the magnetic fields can be remembered using the left hand grip rule for electron flow.

If using positive charges or conventional current (+ to -) then the right hand can be used.

If a current-carrying wire or other moving charge is placed in a stationary magnetic field it experiences a force due to the field produced by the moving charge and the stationary field.

The direction of the force is perpendicularto the direction of movement and the stationary field lines. This is the principle behind an electric motor.

If a conductor is moved through a stationary magnetic field, a current is induced. This is the principle behind an electric generator.

This can be remembered with Fleming's Right Hand Rule for electron flow:

• the thuMb shows the Movement of the wire or other conductor
• the First finger shows the Field
• these induce a Current to flow, represented by the seCond finger