Bending
Water
Needed:
- Nylon
- Comb
- Rubber balloon
- Water faucet
Experiment:
Adjust the faucet to produce a stream of water about
1/16 inch (1.5 millimeters) in diameter. Run the comb through
your hair several times. Slowly bring the teeth of the comb
near the stream of water, about 3 or 4 inches (8 to 10 centimeters)
below the faucet. When the teeth of the comb are about an inch
(2 to 3 centimeters) or less away from the stream, the stream
will bend toward the comb. Move the comb closer to the stream.
What effect does the distance between the stream and the comb
have on the amount the stream bends? Run the comb through your
hair several more times. Does the comb bend the stream more
now? Change the size of the stream by adjusting the faucet.
Does the size of the stream affect how much the stream bends?
If you have other combs, you can try these to see if some bend
the stream more than others. Also, repeat the experiment using
a balloon that you rub on your hair to build the static charge.
Which deflects the stream more?
Explanation:
A charged object attracts small particles such as dust. The
charge on the object causes a complementary charge to develop
in things near it. The complementary charge is attracted
to the charged object. If the complementary charge forms
on something tiny, such as dust particles, these tiny particles
move towards the charged object. This is why your television
screen becomes dusty faster than a cabinet. When a television
operates, electrons fly within the television tube from the
back to the screen. These electrons cause the screen to become
charged. The charge on the screen attracts the dust. The
comb and balloon attract the stream of water in the same
way. The charge on the comb or balloon attracts the molecules
of water in the stream. Because the molecules in the stream
can be moved easily, the stream bends.
Scientific Note:
Static electricity is the accumulation of an electrical charge
in some object. The electrical charge develops when two objects
are rubbed against one another. When the objects are rubbed
together, some electrons (charged components of atoms) jump
from one object to the other. The object that loses the electrons
becomes positively charged, while the object that gains electrons,
becomes negatively charged. The nature of the objects has
a large effect on how many electrons move. This determines
how large an electrical charge accumulates in the objects.
Static electricity is more of a problem when humidity is
low. When humidity is high, most surfaces are coated with
a thin film of water, which prevents electrons from jumping
between the objects. |
