Download Design Challenge * Electric Motor

Design Challenge
Electric Motor
Casey Wu
Physics 4B
Nov.-Dec., 2009
Materials
wire
plastic cup
sandpaper
2 magnets
2 alligator clips
battery
Building the motor
Make a coil out of thick wire by wrapping it about 10 times around a tube of paper
and leave a few inches of loose wire at opposite sides.
Wind the wire around the coil to secure it.
Use sandpaper to sand off all the insulation on one end and only one side of the other end.
Take a plastic cup and poke a hole about half an inch from the top. Poke another hole
directly under the first hole, but about half an inch from the bottom. Create two similar
holes on the opposite side.
Poke a wire through each set of holes, in one hole and out the other. Sand off the insulation
at the bottom end of both wires.
Bend the top end of both wires to make a sideways S.
The magnets’ fields are
crucial to the success of the
motor. This field, together
with the magnetic field of
the coil, either pull or repel,
forcing the coil into
movement.
Rest the coil on the perch created by the twisted wires.
Put magnets directly under the coil, one outside the cup
and the other magnet inside the cup.
The coil is spinning!
electricity is flowing
through the circuit
Connect the sanded ends of the two wires
to a battery using alligator clips.
Related Terms
electricity
magnetism
current
voltage
circuit
heat
electrical energy
mechanical energy (potential and kinetic)
Why this motor works
Electrons flowing through a wire (in this case, the
coil) creates a magnetic field. This magnetic field
is repelled by that of the permanent magnets. So,
with half the insulation sanded off one end of the
coil, the coil alternates between a) having an
electric current running through it and being
pulled or repelled by the magnets and b) falling
back down/continue moving because of inertia
when no current passes through.
ENERGY
An electric motor converts electrical
energy into mechanical energy, which is in
the form of either potential energy, kinetic
energy, or both. Potential energy is energy
that an object has because of its position.
The stored energy has the potential to do
work. Kinetic energy is the energy of
motion.
CIRCUIT
This electric motor is a circuit because
current flows from the battery, through
the alligator clips and the wires, into the
coil to make it spin, out of the coil,
through the wire on the other end, and
back into the battery through other
alligator clip. Electrons are able to flow
through.
OBSERVATIONS
Using Logger Pro, I learned that the motor
makes 14 rotations per second while running
on a 1.5V battery.
Some of the electricity flowing through the
circuit caused the coil to heat up. This heating
of the motor is unavoidable.
The motor can spin indefinitely without
coming to a complete stop, but it tends to halt
occasionally and start spinning again in the
opposite direction.
http://www.wikihow.com/Build-a-Simple-Electric-Motor