Try This at Home: Static Electric Slime
Opposite charges attract each other and like charges repel each other.
What You Need
- 150 mL (3/4 cup) vegetable oil
- Up to 400 mL (2 cups) corn starch
- Disposable cup
- Block of Styrofoam
What To Do
Make sure you have an adult with you to supervise this experiment.
Measure the vegetable oil out into the cup. Using the spoon, add a little corn starch at a time until you have a very thick slime.
Rub the Styrofoam block on the hair, carpet, or wool for about 30 seconds.
Make a hypothesis! How do you think the mixture will react when you hold the Styrofoam block close to it?
Allow the mixture to start slowly flowing out of the cup. Hold the Styrofoam block approximately 3 cm (1 inch) from the mixture. What happens to the mixture.
Try moving the Styrofoam block around near the mixture. Does the mixture move?
As you rub the Styrofoam block on your hair, it is stripping negatively charged electrons from your hair. The added electrons give the block an overall negative charge. Similarly, the mixture strips electrons from the spoon as you stir it, making the mixture negatively charged as well. Like charges repel, so the negatively charged Styrofoam block repels the negatively charged mixture. This is similar to holding two magnets together. When the north and south ends of two magnets are facing one another they will attract; opposites attract. When you hold either north or south poles facing each other, the magnets will repel. Although magnetism and electricity are different concepts, this is still a nice analogy to see the forces of attraction and of repelling.
Lightning can strike the same place twice... the Empire State Building is struck by lightning about 20 times each year.