Electric Charge and Static Electricity Presentation

2. ROY SULLIVAN

3. 1942-
1977

5. ELECTRIC CHARGE
AND STATIC
ELECTRICITY

6. ELECTRIC CHARGE
• All matter is made up of atoms
• Atoms contain
• Protons (+)
• Neutrons (0)
• Electrons (-)

7. LAW OF ELECTRIC CHARGES
• Like charges repel, and opposite
charges attract.
• Protons→positively charged and
electrons→negatively charged,
thus attract each other.
• Without this attraction, electrons
would not be held in atoms.

8. LAW OF ELECTRIC CHARGES
• Like charges repel, and opposite
charges attract.
• Protons→positively charged and
electrons→negatively charged,
thus attract each other.
• Without this attraction, electrons
would not be held in atoms.

9. LAW OF ELECTRIC CHARGES

10. ELECTRIC FORCE
The force between the
charged objects is an
electric force.
The size of the electric force depends on 2 things:
1. The amount of charge (the greater the charge, the
greater the force)
2. The distance between charges (the further the distance,
the less the force)

11. ELECTRIC FIELD
An electric field is the region around a
charged object where electric forces can be
exerted on another charged object.
(Repelled or attracted)

12. CHARGED OBJECTS
Atoms do not have a charge because the number of
electrons and protons cancel each other out.
Ex.
3 protons (+) & 3 electrons (-) = 0

13. How do objects get charged?
• They either gain or lose electrons.
• Why not protons?
Ex.
3 protons (+) & 5 electrons (-) =
7 protons (+) & 2 electrons (-) =
CHARGED OBJECTS

14. HOW CAN YOU CHARGE THE
OBJECTS?
There are 3 ways objects can be charged:
1. Friction
2. Conduction
3. Induction
**In each of these, only the electrons move. The
protons stay in the nucleus**

15. FRICTION
Charging by friction occurs when electrons
are “wiped” from one object onto another.
Ex.
If you use a cloth to rub a plastic ruler,
electrons move from the cloth to the ruler.
The ruler gains electrons and the cloth loses
electrons.

16. CONDUCTION
Charging by conduction happens when electrons move from one
object to another through direct contact (touching).
Ex. Suppose you touch an uncharged piece of metal with a
positively charged glass rod. Electrons from the metal will
move to the glass rod. The metal loses electrons and becomes
positively charged.

17. INDUCTION
Charging by induction happens when charges in
an uncharged object are rearranged without
direct contact with a charged object.
Ex. If you charge up a balloon through friction
and place the balloon near pieces of paper,
the charges of the paper will be rearranged
and the paper will be attracted to the
balloon.

18. CONSERVATION OF CHARGE
• When you charge something by any method, no charges are
created or destroyed.
• The numbers of electrons and protons stay the same. Electrons
simply move from one atom to another, which makes areas that
have different charges.

19. CONDUCTORS AND INSULATORS
• An electrical conductor is a material in
which charges can move easily.
• Most metals are good conductors because
some of their electrons are free to move.
• Conductors are used to make wires. For
example, a lamp cord has metal wire and
metal prongs.
• Copper, aluminum, and mercury are good
conductors.

20. • An electrical insulator is a material in which
charges cannot move easily.
• Insulators do not conduct charges very well
because their electrons cannot flow freely.
The electrons are tightly held in the atoms of
the insulator.
• The insulating material in a lamp cord stops
charges from leaving the wire and protects
you from electric shock.
• Plastic, rubber, glass, wood, and air are good
insulators.
CONDUCTORS AND INSULATORS

21. STATIC ELECTRICITY
Static electricity is the
electric charge at rest
on an object.
When something is
static, it is not moving.
The charges of static
electricity do not move
away from the object
that they are in. So, the
object keeps its charge.
Ex. Clothes taken out
of a dryer

22. ELECTRIC DISCHARGE
The loss of static electricity as charges move
off an object is called electric discharge.
Sometimes,
electric
discharge
happens slowly.
Ex: static on
clothes
Sometimes, electric
discharge happens
quickly.
Ex. wearing rubber-
soled shoes on carpet,
lightning

23. HOW LIGHTNING FORMS

24. LIGHTNING
• Lightning usually strikes the highest point in a charged area
because that point provides the shortest path for the charges to
reach the ground.
• Anything that sticks up or out in an area can provide a path for
lightning.
• A lightning rod is a pointed rod connected to the ground by a
wire.
• Objects, such as a lightning rod, that are joined to Earth by a
conductor, such as a wire, are “grounded.” Any object that is
grounded provides a path for electric charges to move to Earth.
• Because Earth is so large, it can give up or absorb charges
without being damaged.
• When lightning strikes a lightning rod, the electric charges are
carried safely to Earth through the rod’s wire. By directing the
charge to Earth, the rods prevent lightning from damaging
buildings.