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This experiment was conducted to find the amount of energy lost due to friction in DC motors. The testing was done using 30 watt, 50 watt, 70 watt and 100 watt DC motors.


Friction loss in a DC motor will increase as the power and size of the motor is increased.

Scientific Terms

DC motor, armature, stator, commuter, brushes, magnetic leakage


DC motors

A DC motor consists of a rotating part called an armature and a stationary part called a stator. The stationary stator will have coils made out of copper wire called field coils. The rotating armature will also have copper coils wrapped around an iron core. A metal shaft which can rotate on the bearings is located in the middle of the metal core. The wires that come out of the armature coils will terminate at the commuter. This is the place where electrical contact between the armature and the stator is made.

The function of the motor is to convert electrical power into mechanical power. However, not all the electrical energy supplied to the motor can be converted into mechanical energy. Some of the power will be lost and be dissipated as heat from the surface of the motor.

Several types of losses will occur in a motor. The current that flows in the coil will cause copper losses in the stator and armature. The iron core in the armature will produce core losses. Friction losses will happen at the bearing and brushes. The magnetic leakage will cause stray load losses.

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Complexity level:
Project cost ($):
Time required:
1 hour to prepare, 1 day for the science project experiment
Material availability:
Motors will have to be purchased from an appropriate hobby store
Safety concerns:

Handle all electrical devices and motors with care to prevent electric shock/injury from moving parts. The assistance and supervision of a suitably qualified adult is required.