balloons and/or
hard rubber/plastic comb (washed and dried well)
wool
cameras
Getting
started
Mission
1
Tie one end
of at least 12" of thread to a piece of cereal, then hang the cereal
where it doesn't hang near anything else.
Charge a comb
by pulling it several times through dry hair (until the hair crackles and
starts to stick to it), or an inflated balloon by rubbing it on hair or wool.
Bring the comb/balloon
slowly next to the cereal and observe.
Hold the comb
still for a moment by the cereal. What happens?
Now watch as
you bring the comb close to the cereal again.
Mission
2
Charge the comb/balloon
again.
This time, hold
it near a thin stream of water from a faucet.
Can you make
the water "follow" the comb around?
Mission
3
Get a friend
charge two inflated balloons, making sure to rub them all over.
Tie a piece
of thread to each balloon, and hold the string so the balloons hang straight
down.
Slowly bring
the balloons together and see what happens.
Next, put a
hand between the balloons when they're close together.
What if you
cover the hand with a sock and put it between the balloons?
What if you
rub one charged balloon with the sock first?
What next
Creation
and invention:
Make posters
illustrating your findings.
Videotape your
experiments, then write a script to explain to a viewer what's happening.
Discussion:
What's happening
in these activities?
For Mission
1, does it matter if you rub the whole balloon? If you don't, does it matter
which side you point at the cereal?
Why did the
cereal move toward the comb, then away?
Why were we
able to move the water in Mission 2?
In Mission 3,
why did the balloons behave differently toward the bare hand and the hand
covered with the sock before and after we rubbed it on the balloon?
Field
trip possibilities:
Local
science museum displays on electricity
Local
university physics department to see Van de Graaff generators, for example
