You will be making your own electroscope and testing the ability of various materials to conduct static electricity. You will also be making a list or triboelectric series which arranges materials according to their ability to conduct electrons.
When and electric charge is built up in an object, it is called static electricity. Sometimes, this static electricity can be discharged suddenly, as seen in a lightning bolt across the sky. At other times, this static electricity causes a static cling that is seen on socks just removed from the dryer. Static cling occurs when two objects having different charges such as positive (+) and negative (-) come together. Static electricity can be produced as well as tested using various science fair experiments.
During science fair experiments, static electricity can be measured using an electroscope. You will build your own electroscope to test various materials and find out which ones conduct more static electricity.
foam plate, Balloon, foam cup, clay, drinking straw, aluminum pie pan, aluminum foil, thread, wooden ruler, masking tape, different materials for testing such as nylon, polyester, cotton, aluminum, plastic, copper, wool, tissue paper, saran wrap, and so on.
Making your electroscope
Pierce a Styrofoam cup by pushing a skewer near the base and make holes for a straw to pass through. Put a drinking straw through the cup by putting it in these holes and push it till it sticks out on one side. Now invert the cup and stick it strongly with clay on an upright pie pan.
Make a few knots at one end a thread and make a marble-sized ball with a piece of aluminum foil at the knotted end. Now tape the free end of the string to the straw that is sticking out of the cup in such a way that the ball hangs from the straw and touches the rim of the pie pan. Secure the straw with a tape so that it does not move.
Testing your electroscope
One of the methods used in science fair experiments to create a static electric charge is to rub a Styrofoam plate with some wool. This produces a negative charge on the Styrofoam plate surface. Now lift your electroscope by holding the Styrofoam cup and place it over the charged Styrofoam plate. What happens? The aluminum foil ball moves away from the rim of the pie pan.
Why did this happen? When you placed the electroscope on the Styrofoam plate, the negatively charged electrons travelled to the pie pan and then to the foil ball. Since same charges repel, the ball moved away from the rim of the pan.
Now touch the pan and the foil ball with the tip of your finger and see what happens. The ball will return to normal as it was before, because the electrons were transferred to your finger and the pan and the ball were discharged.
Now it’s time to test different materials.
- Charge different materials with static electricity. You may use materials such as a plastic wrap, a woolen scarf, a fleece sweater, an aluminum sheet, a balloon, and so on.
- Now test each charged material with your electroscope.
- Measure how far the ball is from the pan with a ruler.
- Write down the distance in a table.
- Make a note of which materials can carry an electric charge and which ones do not.
- Since recording data is an important step in science fair experiments, you must arrange your data in order with the most charged ones followed by the least charged ones. This is called a Triboelectric Series.
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