Download Electric Charge and Static Electricity

Electric Charge and
Static Electricity
Review of Heat Energy
• http://studyjams.scholastic.com/studyjams/j
ams/science/energy-light-sound/heat.htm
Types of Charge
• Everything is made up of atoms.
• Atoms contain 3 particles – protons,
neutrons and electrons.
• Where are these particles located?
• What is their charge?
Proton and Electron
Interaction
• If two electrons come together, they move
away from each other – they repel.
• If two protons come together, they repel.
• If a proton and an electron come together,
they attract one another.
Key Idea
• Charges that are the same repel each
other. Charges that are different attract
each other.
Repel or Attract?
Electric Fields
• Electric fields are regions around a
charged object where the objects electric
force is exerted on other charged objects.
• Electric fields get weaker the farther they
are from the charge.
Electric Field Lines
• An electric field is invisible. You can use
field lines to represent it.
• A field line shows the force that would be
exerted on a positive charge at any point
along that line.
• Positive charges are repelled by positive
charges and attracted to negative charges,
so field lines point away from positive
charges and towards negative charges
Building Up Charge
• Most object have no overall charge – That
means number of protons equals number
of electrons.
• How does an uncharged object become
charged?
Losing/Gaining Electrons
• It can only lose or gain electrons. It cannot
change the number of protons!
• If it loses electrons what charge is it?
• If it gains electrons what charge is it?
• The buildup of charge on an object is
called static electricity.
• In static electricity, charges build up on an
object, but they do not flow continuously.
Charging Objects
• Charges are never created nor destroyed.
This is known as the law of conservation of
charge.
• There are four methods by which charges
can redistribute themselves to build up
static electricity: friction, conduction,
induction, and polarization.
• What do you think these terms mean?
Friction and Conduction
FRICTION
CONDUCTION
Induction and Polarization
Induction
• In some materials, like
metals, electrons can
leave their atoms. When
metal object comes close
to negative charge, the
negative charges move
away from it. The close
end of the object
becomes positive, the far
end negative.
Polarization
• Electrons can also move
only within individual
atoms. The electrons
react to electric field,
resulting in individual
atoms having charged
ends.
Static Discharge
• If an object becomes charged, it does not
stay that way forever.
• The loss of static electricity as electric
charges transfer from one object to another
is called static discharge.
• Static discharge often produces a spark.
Examples
• Touching a doorknob
• Lightning
Study Jams Video
• http://studyjams.scholastic.com/studyjams/j
ams/science/energy-lightsound/electricity.htm