Headings Electrostatic
Charge Search Questions 
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Electrostatic Shock.
If a high
amount of charge builds up on
an insulator,
it can escape through a small distance in air
to a neutral or
oppositely charged object.
You may have noticed that pulling
off a jumper or shirt
over you head can cause crackling.
If the clothing is made from a
synthetic fibre
(a plastic material which is a good insulator)
then charge is transferred as it rubs
against your hair (also a
good insulator).
The crackling is the sound made by the
charge
jumping between the clothing and your hair through the air.
Touching a car door or a radiator can sometimes give you a shock.
If both the car seat and your
clothing are made from a synthetic fibre,
then one rubs against the other
transferring charge as you step out of the car.
The charge then jumps the small air
gap between your finger and the
car
as you go to close the car door. This
can feel unpleasant.
Similarly, if both the carpet and your
shoes are made from synthetic materials,
then charge is transferred as you walk around.
Touching a radiator will cause the
charge to jump
the small air gap between your
finger and the radiator.
If your clothing, carpet,
shoes etc. are made from natural fibres
then you are much less likely to get a
shock.
Natural fibres such as wool and cotton
attract a small
amount of moisture
(water) to their surface
and this moisture allows the material
to conduct a little
so the charge escapes before it can build
up enough to jump through
air.
If the air itself is moist, the charge
will also escape and no shock
will occur.
When charge jumps across a
small air gap
it causes a spark which can be
dangerous.
Lightning is a natural example of a huge charge
jumping across a very large air
gap,
and we know how dangerous lightning can be.
Headings Electrostatic
Charge Search Questions
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