Electrostatic and Humidity
Name: Jon S.
regarding electrostatic discharge, how does relative humidity becomes
a factor? this event happens particularly in frigid weather where the
humidity is quite low. what's the electrical characteristics of the
air then in this case, more positively charged?
When a bit of static electricity collects up on a surface, all the build-up
is the same kind: all positive or all negative. Since like charges repel
one another, this charge build-up is trying to spread out into the world.
Air does not conduct electricity well. Glass is not a good conductor. If
charge collects on a poor conductor, it cannot move. As a result, you get
static electricity. When your hand comes in contact with it, a route of
escape is provided. The charge spreads out through your skin and your body.
This is the shock you feel.
Water is one of the best electrical conductors in existence. When there is
some moisture in the air, electric charge can enter the water droplets
floating in the air. As droplets bump into other droplets, the charges can
spread out even more. The moving droplets also carry charge to other
surfaces, often to conductors. The more humid the air, the greater the
opportunity to leave the original surface.
Dr. Ken Mellendorf
Illinois Central College
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Update: June 2012