2. Every home has an electricity meter. Do you know where yours is?
Older homes have mechanical meters that look like the ones below.
The cost of your electricity bill depends on how many KWh you consume in a month.

3. What is Electricity?
This term describes all phenomena caused by positive and negative charges.
In your book, p

4. Electric Charges Each proton carries a positive charge.
Each electron carries a negative charge.
Only electrons can be transferred from one body to another.
Having a negative charge means having a surplus of negative charges.
Having a positive charge means having a deficiency in electrons.

5. + - + - + - -
Neutral
Negative
Positive

6. The Coulomb
We are able to measure the electrical charge of an object.
The symbol for electric charge is Q.
The unit for electric charge is the coulomb (C).
The charge of a single electron or proton is x10-19 C. This is referred to as the elementary charge.
How many electrons would be required to have a charge of 1C?

7. 1 Coulomb is equal to the charge of 6.24x1018 electrons.

8. Electrical Forces
Electrical charges of like signs repel each other.
Electrical charges of opposite signs attract each other.
The force between two charged particles is called electrical force.
Electrical Field: The area around the charged objects where the electrical force can be felt. + -

10. Conductors Vs. Insulators

11. Conductors
A conductor is a substance that allows an electric current to move easily.
In order for a substance to conduct electricity, it must contain free electrons.
METALS and ionic substances (in aqueous solution) are among the best conductors, but there is no perfect conductor.
e.g. pure water is a poor conductor, but tap water can conduct electricity

12. Remember: electrolytic solutions

13. Insulators and Semiconductors
An insulator is a substance that reduces current flow by creating resistance.
An insulating substance has few/no free electrons.
There is no perfect insulator.
e.g. air, classified as an insulator, can conduct electricity (lightning): NONMETALS
Examples of insulators: ceramic, plastic, glass, wood, rubber, air
NOTE: metalloids and carbon are semiconductors

14. How do metals conduct?
It is the delocalized electrons involved in metallic bonding that allow metals to conduct electricity.
The delocalized electrons are free to flow through the metal and so carry a current.
Insulating materials do not contain free electrons and so current is unable to flow.
Ionic solutions are also able to conduct electricity because they have mobile charge-carrying particles.
delocalized electrons

15. Homework
Page of
workbook.