Background Information:
When electrons move from place to place, an electric current is created. Not all materials allow electrons to flow though them. Materials that allow electrons to flow freely are called conductors. Materials that do not allow electrons to flow freely are called insulators. In this investigation you will test some common materials and determine which are electrical conductors and which insulators.

Problem: Which materials are conductors and which are insulators?

Materials: 1.5V Dry Cell, 1.5V Lamp With Sockets, 3 Connecting Wires, Test Materials: Penny (Copper); Paper; Wax; Glass; Aluminum Foil; Plastic; Paper Clip; Wood; Rubber; Cloth; Pencil Lead (Carbon).

Procedure:

1. Set up a dry cell, lamp and connecting wires as shown in figure 1. Have your teacher check you setup before proceeding.

Figure 1

2. Keep the ends of the two test wirs about 2cm apart. Bring the ends of the wires into contact with each of the test materials to be tested. Record your observations in the data table.


3. After you have tested all of the materials, disconnect the wires from the dry cell.

Observations:

Analyze Data:

1. Which of the materials you tested are good conductors of electricity?









2. Which of the materials you tested are insulators of electricity?

1. Are metals electrical conductors or insulators?




2. Are nonmetals electrical conductors or insulators?




3. What does this say about the particles of a conductor?




4. Why is most electrical wiring, such as the connecting wires used in the investigation made of copper?





Going Further Strip about 8cm of wood away from one side of a pencil to expose the lead core inside the pencil. Hold the two ends of your test wires as far apart as possible and touch them to the lead core. Slowly move the wires closer together and observe what happens to the lamp. Use what you have learned in this investigation to explain your observations.






Additional Conclusion Questions:


1. How does specific heat relate to conductors and insulators of electricity?
   
2. Using the chart on page 641 in your text, What elements would make the best conductors? Insulators?
   
3. Why don't we use your answers to question 2?
   











© Prentice-Hall, Inc. Return to: Physical Science on the Web