BCIT Physics Department

Demonstration Manual

Electricity and Magnetism

DEM41 - D.C. Motor


- A working model for studying the principle and operation of an electric motor.


The above apparatus and schematic are used for both DEM40 and DEM41.


The Stansi motor is set up identically to that in DEM40, but the knife switch is wired to provide a motor function plus "off" function and a generator function (DEM40). The brushes are arranged on the commutator (not on the slip rings).

The Cenco motor can be wired for shunt-wound operation or series-wound operation (armature and field windings in parallel or series).


  1. The DPDT knife switch must be returned to the "center-off" position to avoid overheating the field coil.

  2. The OHP meter for DEM40 is inoperative when the assembly is switched to "motor."

  3. Demonstrations DEM40 and DEM41 are very conveniently presented together as one package, with selection made via the knife switch.