In the Classroom

  Science Discipline(s) Physics   Topics
  • Electric currents
  • Magnetic force
  • Magnetic fields
  Activity Title Make a Motor   Materials
  • 100 AA batteries
  • 100 magnetic wires
  • 100 small permanent disc magnets
  • 200 paper clips
  • Sand paper
  • Box of toothpicks
  • Tape
  • Play dough
  • Safety goggles
  Procedure
  • Making the armature:
    • Wrap a strip of wire around a battery tens times, leaving two inches of wire on each end
    • Remove wire from battery and make the coil more loop-like by squishing it together like a spring
    • Wrap each end of the wire around the loop twice to hold the loop in place while still leaving the two ends extended out and on opposite ends from each other
    • Use sand paper on one of the ends to rub off the enamel insulation and then strip the other end, radially
      • Allows coil to turn on for part of rotation and off for the other
  • Using a toothpick, twist open two paper clips so that there is a small loop in the middle
  • Tape these paper clips to each end of the battery
  • Stick play dough to the table and put the battery in it to keep it upright (with the paper clips pointing up)
  • Insert the extended strands of the coil into each loop so that the whole thing runs the length of the battery
  • Place a small, disc magnet in the middle of the battery, under the wire
The wire should begin to spin, but if it doesn’t, tap on it until it begins   Questions  
  • What are the three components of a direct current motor and how do they work together?
  • What factors determine the speed of the motor?
  • What makes the motor spin?
  • What happens when the other magnet is used?
  Explanation PK – 3rd grade: Have you ever taken a magnet and moved it close to a compass?  The needle on the compass moves and points toward the magnet. A motor uses a very similar process to change electricity into the rotation of the shaft of a motor. 4th – 6th grade: A DC motor is composed of a magnet called the stator, a rotor called the armature, and a power source. Magnets have two poles, north and south. These poles are attracted to each other, north to south. Two of the same pole, however, will repel one another. When electricity flows through a piece of wire, a magnetic field in generated around the wire. By winding the wire around the armature, placing it near a magnet, and running electricity through the wire, we can cause the armature to spin. Middle School: A DC motor is composed of a magnet called the stator, a rotor called the armature, and a power source. Magnets have two poles, north and south. These poles are attracted to each other, north to south. Two of the same pole, however, will repel one another. The power source provides a current to the armature, which is coiled in a loop at a right angle above the magnet. An electric current in a magnetic field will experience a force. The two sides of the looped armature experience forces in opposite directions. The two forces create a turning influence, called torque, to rotate the armature. The motor’s speed depends on the amount of current in the wire, the length of the wire (number of loops), and the size of the magnetic field. Increasing one or all of these will make the motor spin faster.   Next Generation Science Standards
  • 3-PS2-1 (PS2.A): Plan and conduct an investigation to provide evidence of the effects of balanced and unbalanced forces on the motion of an object
  • 3-PS2-4 (PS2.B): Define a simple design problem that can be solved by applying scientific ideas about magnets
  • 4-PS3-2: Make observations to provide evidence that energy can be transferred from place to place by sound, light, heat, and electric currents
  • MS-PS2-3: Ask questions about data to determine the factors that affect the strength of electric and magnetic forces
  • MS-PS2-5: Conduct an investigation and evaluate the experimental design to provide evidence that fields exist between objects exerting forces on each other even though the objects are not in contact