Electricity flows into our homes through metal wires. What else can it flow through? Conductors are materials through which electricity can flow and insulators are materials through which it cannot. A variety of things found in the classroom or around the house can be tested for their ability to conduct electricity.
1 battery holder
1 flashlight bulb
1 bulb holder
3 alligator clips
Metal thumbtacks or brads
What To Do
Place the battery in the holder and attach an alligator clip to each of the leads on the battery holder. Connect the light bulb, in its holder, to one of the wires that is attached to thebattery. Connect another alligator clip to the other lead on the light bulb holder. Cut a piece of cardboard roughly 2 inches by 2 inches. In the center of the cardboard insert two metal thumbtacks or paper fasteners about ½ inch away from each other. Connect one of the remaining alligator clips, one leading from the battery and one leading from the light bulb, to each of the thumbtacks. An open circuit has been created, with the gap between the thumbtacks serving as the break in the circuit. Test various materials for their conducting ability by using them to bridge the gap between the thumbtacks. Conductors, such as coins, lying across the gap in contact with the thumbtacks should make the light bulb light. Insulators will not because they do not complete the circuit.
1. Why does the bulb light when some things are used to connect the tacks, but not others?
2. What materials made the bulb light? Could you guess which other materials would be conductors or insulators?
"The Science Book of Electricity." Neil Ardley, Harcourt Brace and Company: London, 1991, p. 20-21.
"Science Experiments with Electricity." Sally Nankivell-Aston and Dorothy Jackson, Franklin Watts: New York, 2000 p. 16-17.
© S. Olesik, WOW Project, Ohio State University, 2001.