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How to Build a Science Fair Electric Motor With Brushes

A working electric motor made from scratch makes an educational science fair project for students in sixth through eighth grades. It's rewarding watching the armature of the direct current motor you made spin. You'll learn about electric currents and the relationship between electricity and magnetism. This simple electric motor operates using electrical contacts, called brushes, between the stationary wires and moving parts of the motor. The name "brushes" came from contacts made of copper brush that were used in early motor designs. The contacts in newer motors are usually made of carbon.

Things You'll Need

  • Battery holder with battery, size C or D
  • Magnet
  • Enamel-coated No. 22 wire, 1 yard
  • 4 pieces bare No. 18 or No. 20 copper wire, 6 inches each
  • AA battery
  • Sharp knife
  • 2 small glass beads with openings large enough to fit the No. 22 wire
  • Small strip of paper
  • Duct tape
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Instructions

    • 1

      Wind the enamel-coated wire 25 to 30 times around the battery in a tight coil, leaving 2 to 3 inches of wire free at each end. This forms the armature, the part of the motor that moves. Carefully slide the wire coil off one end of the battery, holding the coil to keep it from springing out of shape. Wrap the free ends of the wire two times around the coil, on opposite sides, so the coil can rotate on an axis formed by the ends of the wire.

    • 2

      Hold the coil straight up and down on the edge of a table, with a free end of the wire lying flat on the table. Strip the top of the insulation off the wire, from the end to the coil, leaving the bottom side with the insulation intact. Repeat this process with the other free end. The bare portion of both wires should face up.

    • 3

      Bend a small loop in the center of each of two pieces of bare wire to make the axle supports. They should resemble the looped end of a safety pin. Thread the ends of each axle support through one of the holes at each end of the battery holder. Wind the ends through the hole several times. Thread a glass bead onto each axle end. Place the armature ends into the axle support loops. Adjust the loops on the axle supports so the wire coil can spin freely without touching the coil.

    • 4

      Connect one end of a remaining bare wire to the base of one axle support. Connect one end of the last bare wire to the remaining axle support. Bend the wires so they cross to the opposite axle and lie on top of the axle without touching any other wires.

    • 5

      Hold the strip of paper over one battery terminal, and place the battery in the holder. Lay the magnet on top of the battery holder. Check that the coil can spin without hitting the magnet. Tape the battery holder to the table with the coil on top.

    • 6

      Start the motor by removing the paper strip and completing the circuit. If it is reluctant to start, give the coil a gentle push.

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