1. Inflate both balloons so they are the
same size. Tie a knot in the neck of each balloon so that the air
does not escape.
2. Tie one end of the string to one of the balloons.
3. Using tape, secure the free end of
the string to the edge of a table.
4. Charge the second balloon by rubbing
it with the wool scarf.
5. Hold the charged balloon near, but
not touching the hanging balloon.
6. Observe the motion of the hanging
balloon.
Sum it up!
Before rubbing, like all materials, the balloons and
the wool scarf have a neutral charge. This is because they each
have an equal number of positively charged subatomic particles
(protons) and negatively charged subatomic particles (electrons).
When you rub the second balloon with the wool scarf,
electrons are transfered from the wool to the rubber because
of differences in the attraction of the two materials for electrons.
The balloon becomes negatively charged because it gains electrons
from the wool, and the wool becomes negatively charged because
it gains electrons from the wool, and the wool becomes positively
charged because it loses electrons.
When the negatively charged balloon is brought near the
neutrally charged hanging balloon, the electrons on the surface
of the hanging balloon move away because like charges repel.
This leaves the surface facing the charged balloon more positive.
Since opposite charges attract, the positive charge on the surface
of the hanging balloon is attracted to the negative charge on
the hand-held balloon. This attraction is strong enough to move
the hanging balloon.
Kids Science Experiments & Science Projects
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