PHYSICS 202
DC MOTOR ACTIVITY
Objective: Take apart a DC motor and determine how it works electrically as well as
magnetically.
1.
Create a semi-scale diagram, which shows the physical design of the inside of the motor.
You may need to draw a couple of views to capture how the motor is constructed.
2.
Describe how the motor works electrically.
Use a schematic diagram (you may need more than one) & your scale diagram to help
write a description of how the current flows through the coils of wire. The DC motor has a
“commutator” in it, which switches the current from one direction to another through the
coils as the coils rotate. Be sure to describe/draw how this commutator works for one full
rotation of the coils.
3.
Describe how the motor works magnetically.
First determine how the magnetic poles of the permanent magnets are arranged using a
compass. Then use F = Il X B and diagrams to explain how the magnets in combination
with the current in the wires force the motor to turn . . . OR . . . Use  =  X B - magnetic
dipole moments to explain the rotation of the motor. Explain/draw how this torque turns the
coils for a full rotation.
4. Make your own motor using ‘magnetic’ wire, magnets, safety pins, cardboard and a battery.
Show me your working motor & write a brief description of the procedure in making it work and
how you think it works.