Michigan Science
Standard VI.1 Matter and Energy: All
students will measure and describe things around us; explain what the
world around us is made
of; identify and describe forms of energy; and explain how electricity and magnetism
interact with matter.
Elementary Benchmark 6:
Describe interaction of charged materials with other charged
or uncharged materials.
3. Technology
productivity tools
·
Use general purpose productivity tools and
peripherals to support personal productivity, remediate skill deficits, and
facilitate learning throughout the curriculum.
· Use technology tools (e.g. multimedia authoring, presentation, Web tools, digital cameras, scanners) for individual and collaborative writing, communication, and publishing activities to create knowledge products for audiences inside and outside the classroom.
Objective:
Students will recognize that static electricity is due to a lack or surplus of
electrons.
·
Worksheet (1 per student)
·
Transparent tape
Imagine this situation: You are at home relaxing; your shoes are off and you are watching your favorite movie. The doorbell rings, so you jump up to answer the door, wondering who is out there. You run across the carpeted room and reach out for the metal doorknob. ZAP! You receive a shock. What caused this shock? (Static electricity) How does static electricity work?
Explore
Today we are going to investigate static electricity, what causes it and how it works. Working in groups of 4, the students will explore static electricity through the tape experiment in their science textbooks.
Step 1: Give each group
of 4 students two pieces of tape about 10 cm long.
Step 2: Stick the tape to the desktop, leaving about 1 cm over the edge. Fold the edge back so that there’s a nonstick part to grab.
Step 3: Pull the strips off your desk, one at a time, so that the tape doesn’t curl up.
Step 4: Hold the two strips by their ends and bring them close to each other. What happens? Write your observations on your worksheet. (Students should find that the strips repel each other.)
Step 5: Have your partner stroke both of the strips several times with his or her fingers. Bring the strips together again. What happens? Write your observations on your worksheet. (Students should find that the strips don’t interact with each other.)
Step 6: Stick one of the strips back on your desk. Now stick the other one right on top of it.
Step 7: Peel both strips off your desk. Now, peel the two strips apart. Predict what will happen when you bring the two strips together. Write your prediction down.
Step 8: Test your prediction and write down your observation. (Strips should be attracted to each other.)
Step 9: Have your partner stroke the strips several times again. Predict what will happen when you bring the two strips together after they have been stroked.
Step 10: Test your prediction and record your observations. (Strips should not interact.)
Develop
In your experiment, you found that sometimes the strips of tape pulled toward each other, sometimes they pushed each other away and sometimes they did not do either. Each piece of tape has an electrical charge; this charge can be either positive (+) or negative (-). In the last chapter we learned that all matter is made up of very tiny pieces called atoms. Atoms are made up of electrons, which have a negative charge, and protons, which have a positive charge. When the pieces of tape had the same amount of positive and negative charges, or protons and electrons, they didn’t pull toward or push away from each other.
When the tape was pulled off the desk, both pieces pulled electrons from the desk. They both had more negative electrical charge and pushed away from each other. When two objects push away from each other, we say that they REPEL each other. When the two pieces of tape that were stuck together were pulled off the desk they had extra electrons. By puling them apart, the sticky side pulled most of the extra electrons off the bottom piece, which gave the top piece more negative electrical charge. The bottom piece had many fewer electrons than it started with so it had more electrical; charge. Since the two pieces had opposite charges, they were ATTRACTED to each other - they pulled toward each other.
The results we saw in our experiment were due to STATIC ELECTRICITY. It is called static electricity because the electrical charge is on something and not moving (even though it moved to get there).
Can you think of a time when you have seen the results of static electricity? (Clothes out of the dryer, frizzy hair when you take a hat off in the winter) When large amounts of static electricity build up, the results can be harmful. I am sure you have all seen lightning before; lightning occurs as the result of a very big build up of static electricity. It builds up in the clouds, as the atoms bump and rub against each other. When the built-up electricity travels to the ground, we see lightning.
Adapted from: Electrical Energy published Macmillan/McGraw-Hill School Publishing Company, 1993.