How to Make a DC Generator for a Science Project

Electricity is generated by spinning loops of wire in a magnetic field.

You can use everyday items to make a simple DC generator. To generate an electric current, all you need do is move a conducting material, such as copper wire, through a magnetic field. This is because electricity is caused by the flow of electrons from an area of high electric potential to low electric potential. The difference in electric potential between two points is called the voltage of the circuit.

Things You'll Need

• Straight, non-conductive rod
• 1 foot of insulated copper wire
• 2 bar magnets, each 2-inch
• 3- by 14-inch cardboard
• 3 strips aluminum
• 1 small, low-voltage light bulb, such as an LED
• Scissors
• Double-sided sticky tape.

Instructions

1. Fold the cardboard into rectangular prism. The length of the longest side must be shorter than the rod. The width must be wide enough to fit both magnets and the rod with copper wire wrapped around it. A pen or pencil makes a good rod.

   Attach the magnets to opposite long sides of the rectangle, with opposite poles facing one another. Pierce holes in the short sides of the rectangle so the rod can spin freely.

2. Cut 2 inches off the copper wire and coil the rest around the rod, leaving 2 inches of copper wire free on both ends. Pass both free ends along the rod, and out of the same end of the box. Strip the insulating cover from the last half-inch of each end. Wrap double-sided sticky tape once around the rod, to fasten the wire to the rod.

3. 

   Aluminum cans are good sources of thin conducting material.

   Cut three thin strips of aluminum. If cutting them from a can, be careful. Measure the first strip by wrapping it once around the rod and the two exposed wire connections. Cut it into two halves, and trim each end.

   This creates a split-ring connector, which forces the electricity to travel in only one direction in the circuit. Without the split ring, the generator will produce AC electricity.

4. Fasten each half to the rod so it covers one of the exposed wires. The tape on the rod will hold it in place. The halves must not touch.

   Bend the other two strips so they form "L" shapes, touching on one side of the split ring. Attach the other end of the strips to copper wires fastened to the light bulb, to complete the circuit.

   Spin the rod to light the bulb.

Tips & Warnings

• The magnetic field must be moving for electricity to be generated, which is why dynamos on bicycles don't work unless the pedals are turning.

• Because the amount of electricity generated is proportional to the size of the magnetic field, using a more powerful magnet reduces the speed the rod must be turned to turn on the light.

• Adding a handle makes turning the rod easier.

• Take care when working with electrical currents.

• When cutting aluminum cans, be careful of sharp edges. Get an adult to cut the conducting strips for you, if possible.

References

• James E. Koehler: 4 - Basic DC Generator

Resources

• University of New South Wales School of Physics: Electric motors and generators