1. Electricity
Chapter 17.1

2. Section 1: Electric Charge and Static Electricity
All matter is made up of very small particles called atoms.
Atoms are made of even smaller particles- protons, neutrons, and electrons.
The charged particles of atoms are protons and electrons—protons are positively charged and electrons are negatively charged.

3. Unlike Charges Attract
Charges Exert Forces
Charge is a physical property-an object can have a positive charge, a negative, or no charge.
Charged object exert a force-a push or pull-on other charged objects.
The Law of Electric Charge -states that like charges repel, or push away and opposite charges attract.
Because protons are positive and electrons have opposite charges, they are attracted to each other.
Without this attraction, electrons could not be held in atoms.
Like Charges Repel
Unlike Charges Attract

4. Charges Exert Forces
The electric force is the force between charged objects.
There are two factors that determine the size of the force are:
The amount of the charge on the object — the greater the charge—the greater the electric force
The distance between the charges —the closer together the charges are—the greater the electric force.
An electric field -the region around a charged object in which an electric force is exerted on another charged object.

5. Three Ways to Charge an Object: Friction
There are three ways to charge an object: friction, conduction, and induction. Atoms become charged when they gain or lose electrons.
Friction – charging by friction happens when electrons are “wiped” from one object onto another.
Ex: Using a cloth and rubbing a plastic ruler- the electrons move from the cloth to the ruler.
Also , rubbing a balloon on your hair causes electrons to move from your hair to the balloon.

6. Three Ways to Charge an Object: Conduction and Induction
Conduction -when electrons move from one object to another by direct contact. Electrons can be transferred from a positively charged object to an uncharged object.
Ex: A negatively charged plastic ruler touches an uncharged metal rod.
The rod becomes negatively charged by conduction.
Induction -happens when charges in an uncharged metal object are rearranged without direct contact with a charged object.
Ex: If you hold a metal object near a positively charged object, the electrons in the metal are attracted to an move toward the positively charged object.

7. Conservation of Charge
Conservation of Charge - When an object is charged by ANY method, NO charges are created or destroyed. Because charges are not created or destroyed, charge is said to be conserved.
Electroscope – used to detect whether an object is charged.

8. Moving Charges
Electrical conductor – is a metal material in which charges can move easily. Most metals are good conductors because some of their electrons are free to move.
Ex: copper, aluminum, and mercury
Electrical insulators – materials in which charges do not move easily. They do not conduct charges very well because electrons cannot flow freely.
Ex: plastic, rubber, glass, wood, and air

9. Static Electricity
Static Electricity – is the electric charge at rest on an object; generally produced by friction or induction.
The term static mans “not moving” so the charges do not move away from the object they are in.
Electric Discharge – is the release of electricity stored in a source or the loss of static electricity as charges move off an object.
Ex: clothes stuck together by static electricity – this happens slowly.

10. Static Electricity: Lightning
Sometimes electric discharge happens quickly. One of the most dramatic examples of electric discharge is lightning.
A lightning rod is a pointed rod connected to the ground by a wire.
They are mounted so that they are the tallest point on a building.
When a lightning strikes a lightning rod, the electric charges are carried safely to Earth through the rod’s wire which prevents lightning from damaging buildings.

11. Lightning Rods

13. The only man in the world to be struck by lightning seven times was ex-park ranger Roy C. Sullivan, the human lightning conductor of Virginia, USA.
A single lightning strike is made up of several 100 million volts (with peak current in the order of 20,000 amps).
His attraction for lightning:
1942 (lost big toe nail)
1969 (lost eyebrows)
July 1970 (left shoulder seared)
April 1972 (hair set on fire)
August 1973 ( hair and legs seared)
June 1976 (ankle injured)
June 1977 (chest and stomach burns).