Voltage/Potential Difference
Electricity and Magnetism

Electric motor, fractional horsepower

Teaching Guidance for 14-16 PRACTICAL PHYISCS

Unfortunately, this type of motor is no longer made: it has been replaced with an AC induction motor. However, many secondary schools have one of the older type which can be used for this demonstration.

These motors have separate power connections: one for the rotor (armature) and one for the field coils, usually via 4-mm sockets. Details of the electric shock hazard are given in CLEAPSS Bulletin 114, summer 2002.

This label can be printed for attachment to the motor:

Safety: Danger of electric shock

High voltages can be developed at the terminals of this motor. All connections must be made using leads with sprung shrouded plugs. Switch off all power supplies before altering connections. For use by staff and supervised sixth-form students only.

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