The purpose of my experiment is
to demonstrate the existence of
the Electro Motive Force using a
Homopolar Motor.
 If an electric circuit is made to interact
with a magnetic field, then a rotary
movement is induced.
 If the direction of the current in the
circuit is reversed, then the direction of
rotation changes.
I assembled the Homopolar Motor using the
following items:
Magnet
Copper wire
Battery
First Method
I attached the magnet under the battery. I took the
copper wire and made it into a coil that could be
suspended around the magnet and battery. One end of the
coil touched the top end of the battery while the other
touched the magnet, thus completing the circuit.
Second Method
I attached the magnet to a screw which in turn was
attached to the bottom end of the battery. I completed the
circuit by placing the copper wire between the top end of
the battery and the bottom of the suspended magnet.
Faraday's Law is a basic law of
electromagnetism that predicts how a
magnetic field will interact with an
electric
circuit
to
produce
an
electromotive force (EMF). It is the
fundamental operating principle of
electrical motors and generators.
Fleming’s Left Hand Rule states that
when current flows in a wire, and an
external magnetic field is applied across
that flow, the wire experiences a force
perpendicular both to that field and to
the direction of the current flow.
Observations after the motor was assembled:
First method: I saw the copper wire spin around the
battery and the magnet when the circuit was completed.
Second method: I saw the magnet spin when the circuit
was completed.
Method
Polarity of the
Battery
Direction of Rotation
FIRST METHOD
Copper wire rotates clockwise
FIRST METHOD
Copper wire rotates counter
clockwise
SECOND METHOD
Magnet rotates clockwise
SECOND METHOD
Magnet rotates counter clockwise
» The rotary movement is due to the presence of
the Electro Motive Force. The direction of
rotation is based on Fleming’s Left Hand Rule.
» Reversing the polarity of the battery changes
the direction of rotation.
» The speed of rotation is dependent on the
charge in the battery! A new battery provides
more current, so the rotation is fast. As the
battery loses charge, the speed of rotation
gradually comes down.
Based on our observations, data and
results, we can conclude that:
“When a Magnetic Field interacts with an
Electric circuit an invisible force called the
Electro Motive Force is produced”.
This is the fundamental operating principle
of an Electric Motor.
 ELECTRIC MOTORS
 ELECTRIC GENERATORS
 LINEAR MOTORS
 MAGNETIC LEVITATION