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activity: Unusual
Water
What
you will need:
- polythene strip
- dry soft cloth, like a duster
What
you need to do:
- Rub the polythene strip with the dry, soft cloth. This knocks
electrons off the cloth and onto the polythene strip. The polythene
strip now has static electricity.
- Turn on a tap, so a steady stream of water is coming out.
- Put the polythene strip next to the stream of water. Don't let
the water touch the strip.
What
do you observe?
- What happens to the water when the polythene strip is close
to it?
- Rubbing the polythene strip with the cloth knocked negative
electrons off the cloth. What charge did this give the cloth?
- The negative electrons went onto the polythene strip. What charge
did this give the polythene strip?
When you've used magnets, you should have found that two similar
poles will repel (push away) each other. So, a north and a north
pole put together will push each other apart. Two different poles,
a north and a south pole, will attract each other. This works for
charges as well. Two objects with the same charge will repel, and
two objects with different charges will attract each other. So,
a + and + will repel, but a + and - will attract.
Question
- What charge must water have? Explain your answer.
Click here to
check your answers.
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