PAPER CLIP MOTORS [30 minutes]
Intro:
Most people think of the wealth of our society in terms of dollars, but you can also think of
it in terms of the amount of energy we use. Electric motors are our mechanical servants
(turning laundry, spinning a fan, powering a light, etc.), and these motors are the reason
why we are wealthier than in the past.*
Background:
A motor is the inverse/opposite of a generator. We are applying a current (the battery,
chemical energy) to create mechanical force. ​
How does it work? When electric current
flows through a coil of wire, it can generate a magnetic field (electromagnet). When you
place a magnet near this electromagnet, the magnetic fields will want to align (you are
probably familiar with magnetic repulsion from playing with refrigerator magnets). This
will cause the coil to rotate. Since one arm of the coil only makes the electrical connection
half the time when it rotates, it will break the connection (thus stopping the
electromagnet), and the coil will fall down due to gravity. Falling will rotate the wire,
making the electrical connection again. This is what makes the coil go in a full circle.
Materials:
Copper Wire, 2 paper clips, AA batteries, Battery pack, Cardboard, Sandpaper and Magnet
Procedure:
1) Create a stand using paper clips (see figure below), and tape them to a piece of
cardboard
2) Connect the AA battery pack to the paper clips (hook the red wire to one paper clip and
the black wire to the other).
3) Make a smooth coil with the copper wire and leave two arms sticking out.
4) Using the sandpaper, sand off the coating on one arm all the way around (this allows
electrical connection to the battery as the coil spins) and on only one side of the other arm.
5) Set the coiled wire on the paperclip stand and place the magnet underneath.
Give the wire a small push with your finger, and this should cause the coil to spin.
[Insert Image here]
Additional things to try:
● Change battery strength (AA, 9V)
● Use a wire with both sides fully sanded
● Flip the magnet
● Create a ring with more coils
Alternate Procedure for an easier Paper-Clip Motor Setup
● Manipulate your paper clips to create a ‘stand’ for the copper coil.
● Connect the open ends of the paper clips to the two ends of a battery. Using black
electrical tape, secure the connection between the paper clip, and the battery end.
Place your copper wire on the paper clip stand, as well as the magnet on top of the
battery. If the coil does not start spinning, either give it a little ‘push’, or use your
fingers to secure the connection.
Questions:
Why does wire get hot?
Why do you have to sand the wire in a special way?
What do you think would happen if both ends of your copper were sanded all the way
through, versus one side being completely sanded, and one half-sanded side?