1. Electricity
Chapter 13

2. Electric Charge
Section 1

3. Positive and Negative Charge
There are two types of electric charge
Protons have positive electric charge
Electrons have negative electric charge
What happens if an atom has an equal number of protons and electrons?
No net electrical charge
Electrically neutral
Do neutrons have an electric charge?
No...neutrons are uncharged particles

4. Transferring Charge
The strength of the attraction between electrons and the nucleus can vary between different types of atoms and molecules
For Example
Electrons are more attracted to atoms in the soles of your shoes than the atom in carpet
Electrons will transfer from the carpet to your shoes
What is the charge of the carpet now?
Positive
What is the charge of the soles of your shoes?
Negative
An accumulation of excess electric charge is called STATIC ELECTRICITY

5. Conservation of Charge
When an object becomes charged
Electrons usually moved from one object to another
Charge cannot be created or destroyed
Charge is transferred
The Law of Conservation of Charge
Charge cannot be created or destroyed, but can be transferred from object to object

6. Charges Exert Forces
The forces that exist between charges are dependent on two things
The type of charge
Like charges repel
Opposite charges attract
The distance between charges
Force decreases as objects move apart
What do you think causes clothes in your dryer to be attracted to one another?
Some clothes gain electrons (negatively charged)
Some clothes lose electrons (positively charged)
Clothes of opposite charge stick together

7. Electric Fields An electric field surrounds every electric charge
The field exerts a force causing other electric charges to be repelled or attracted
Any charge in the field will be pushed or pulled
Electric fields are represented by arrows that show how the field would make a positive charge behave

8. The Strength of Electric Forces
Remember…all objects are attracted on one another by gravitational forces
Electric forces are much stronger
The electric forces between electrons and protons are what keep atoms together

9. Conductors and Insulators
A material in which electrons are able to move easily is a conductor
What type of material make the best conductors?
Metals
A material in which electrons are not able to move easily is an insulator
Can you think of some examples?
Wood, plastic
Thermal insulators and conductors are not always electrical conductors
Can you think of a thermal conductor that is also an electrical conductor?
Can you think of thermal conductor that is not an electrical conductor?
Glass

10. Charging Objects
Rubbing objects together can result in a transfer of electrons
One material has a positive charge and the other has negative charge
This type of transfer is charging by contact
When a charge object comes near a neutral objects, the electrons of the neutral object will rearrange
The neutral object becomes charges
This type of transfer is charging by induction

11. Lightning and Thunder
Lightning is the sudden discharge of charges built up in thunderclouds.
The collisions of atoms and molecules as they move through air cause air to emit light.
Lightning also produces powerful sound waves due to the large amount of heat that causes the surround air to expand rapidly and produce thunder.
To protect objects from being stuck by lighting, they are often “grounded” to Earth. Grounding provides a path for lightning to travel to the ground.
How It Works: Lightning

12. Detecting Electric Charge
Electric charge can be detected using an electroscope