Chapter 7
Static charge is produced by
electron transfer
Electricity: Two Types
 Static
Electricity: (or static charge)
refers to electric charges that can be
collected and held in one place.
 Current
Electricity: the continuous flow
of charge
Review from Unit 2
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All matter is made up
of atoms
The nucleus contains
neutrons (no charge)
and protons (positive
charge)
The nucleus has a
positive charge
Electrons (negative
charge) are around
the nucleus
Charges on objects can change
materials are charged with the transfer of electrons
 The friction between two objects can result in one
object losing electrons and the other object gaining
electrons
 Positive charge: if an object loses electrons
(negative) it has more positive charge than negative
so the object has an overall positive charge
 Negative charge: if an object gains electrons
(negative) it has more negative charge than positive
so the object has an overall negative charge
 Neutral: if an object has the same number of
positive charges and negative charges.

Positively Charged
Negatively Charged
Neutral
Charges on objects can change
 Acetate
and paper towel are both neutral, but rub
them together and paper towel loses electrons
(overall positive charge) and the acetate gains
electrons (overall negative charge)
 Note: the number of charges drawn in the diagrams
does not indicate the exact number of charges. They
just represent the relative numbers.
Paper Towel
Acetate
An object can lose its charge
 Charged
objects, either negative or
positive, become neutral by attaching or
touching a conductor to it.
 The conductor transfers any excess static
charge to the conductor (evenly spread
over the conductor)
 Grounding: connecting a conductor so that
electric charge flows into Earth’s surface.
Electric Discharge:
the removal of an
electric charge
from an object.
Ex: Lightning,
rubbing feet
across carpet
then touching a
doorknob.
Static Electricity Activity
Demonstration
 The

transfer and build up of charge
http://phet.colorado.edu/index.php
Laws of Electric Charges
(Static Charge)
 Like
charges repel (push apart)
 Opposite charges attract (pull together)
Laws of Electric Charges…
 Some
Neutral objects are attracted to
charged objects


Rub a balloon with your hair, the balloon will
pick up electrons and become negatively
charged.
It will be attracted to the neutral wall
Static Knowledge and Technologies
 Electrostatic
air cleaners: removes electrons from
particles in the air and the charged particles are then
attracted to a plate on the device
Lightning Rods: Placed on top of
a building and it protects the
building from lightning
If lightning occurs near the
building the large amount of
charge will pass through the
lightning rod to the ground
rather than the building.
Static Knowledge and
Technologies

Photocopiers:
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light hits paper and
reflects off white part
of the copier
Reflected light hits drum
and removes static
charges in this area
Neutral Toner goes over
drum and sticks to
charged area.
Paper rolls over the drum
and it has stronger
attraction for the toner.
Toner is now “baked” on
the paper
Careers related to Electricity
 Photocopy
Technician
 Linesman
 Electrician
 Engineer