Download PaperClip Motor

BACKGROUND:
Motors convert electrical energy (from a battery) into mechanical energy (used to cause
rotation). When a wire that carries current is placed in a region that has a magnetic field, the wire
experiences a force. The direction of the force depends on the direction of the current in the wire and
the direction of the magnetic field. The direction of the force determines which direction the motor
spins.
The Right Hand Rule is used to determine the direction of the force when the direction of the
current and the direction of the magnetic field are known.
Place your right hand in this position. Your pointer finger
represents the direction of the current. Your middle finger
represents the direction of the magnetic field. Lastly, your
thumb represents the direction of the force.
The disk magnet provides the magnetic field in this simple DC
motor. With the magnet in position, the magnetic field is directed
vertically (out of or into the magnet depending on which side of the
magnet is up)
When the motor sits on the paper clips, so that the loop is oriented
vertically, only the sections of the wire where the current flows
horizontally matter. This is because only the sections of the wire
oriented perpendicularly to the magnetic field experience forces.
In this example the magnetic field is directed upwards. The current
at the top of the wire is directed to the right and the current at the
bottom of the wire is directed to the left. Which way would the
wire circle spin? Answer: The top of the wire would spin towards
us and the bottom of the wire would turn away from us.
Paper Clip Motor
GOAL: Today’s activity is to build and operate a paper clip motor. Motors are a main component in
mechanical systems, which are often used due to their simplicity, efficiency and ease of integration.
Today, we can see motors in hybrid cars, pencil sharpeners and toys. While motors have only been
around for about 150 years, they function by simple principles of electricity and magnetism
MATERIALS:
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(1) D-cell Battery
(2) standard paper clips
3 feet of magnetically-insulated copper strand (usually labeled for use in electromagnetics)
(1) sandpaper
(1) disk magnet
masking tape
PROCEDURE:
1. Wrap the copper wire around the D-cell battery to form
a coil leaving about 2 inches extra of the copper wire on
each end. The ends should be on opposite sides of the
coil from each other. (See to the right)
2. Remove the coil from the battery and place the coil flat
on a surface (the table). Wrap some of the extra wire around the loop to prevent unwinding (see
below picture)
3. Using the sandpaper, rub off all of the insulation from one end of the wire all the way around
4. On the other end, strip off the insulation from only one side of the wire (The purpose of this step
is to allow the coil to turn on for part of its rotation and then turn off on the other part)
5. Follow the steps below to bend the two paper clips (use paper clip shape directly
below, not shape from next page)
a.
b.
c.
d.
7. Tape them to the two electrical contacts of the D-cell (See picture below)
8. Tape the disk magnet to the top of the D-cell (See picture below)
9. Stabilize the battery and place the coil on the top of the two paper clips (See above picture)
10. Gently tap the coil and watch it spin!