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Slide 1

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Static Electricity
When two electrically The material which gains electrons
insulating materials are becomes negatively charged whereas
rubbed together the material which loses electrons
electrons move. becomes positively charged this is
Static electricity= because electrons carry an electrical
charge `held' by a n charge.
insulator or insulated Opposites attract. The same repel.
conductor. Electric current is the
Metals are good conductors of rate of the flow of
electricity because they contain charge.
free, delocalised electrons which
are not confined to a single atom.
Insulators cannot conductor
because all the electrons are held
in atoms.
If a negatively charged, isolated
object is earthed than electrons will The bigger the charge
flow from it to the earth until it is no on an isolated object,
longer charged. If a positively the higher the
charged, isolated object is earthed potential difference
the electrons will flow from the earth between the object
to it until it is no longer charged. and the earth. If the
potential difference
becomes high enough,
a spark may jump
across the gap
between the object
and any earthed
conductor brought
near it.…read more

Slide 2

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The Electrostatic Paint Sprayer
The spray nozzle is connected to the
positive terminal of an electrostatic
generator. The negative terminal is
connected to the metal panel. The panel
attracts paint droplets from the spray. The
droplets of paint all pick up the same charge
and repel each other so form a fine cloud of
paint.
The Photocopier
Photocopiers with a photo conducting drum- Drum positively
charged until light falls on it. Light reflected off the paper
onto the drum. The areas of black do not reflect so the drum
keeps its charge in the areas. The black toner sticks to the
drum where it is still charged and pressed onto paper. The
paper is finally heated to stick the toner to it permanently.
Antistatic Floors
In a hospital, doctors use anaesthetic gases during operations.
Some of these gases are explosive. If the gas escapes into
the air, a tiny spark could make it explode. To eliminate static
charge in operating theatres, an antistatic material is used
for the floor surface. The material is a poor electrical
insulator so it conducts charge to the earth.…read more

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