1. Static Electricity

2. What Is Static Electricity?
A stationary electrical charge that is built up on the surface of a material

3. Two kinds of charges
After being rubbed, a plastic ruler can attract paper scraps because the ruler carries an electric charge.
The two types of charges, positive (+) and negative (-).

4. Where do charges come from?
If electrons = protons neutral
If electrons > protons  gaining electrons, negative charge
If electrons < protons  losing electrons, positive charge

5. Where do charges come from?
Rubbing materials does NOT create electric charges. It just transfers electrons from one material to the other.

6. Where do charges come from?
When a balloon rubs a piece of wool...
Electrons are pulled from the wool to the balloon. Or the fabric to the ruler. + – –
Now, the balloon has more electrons than usual.
wool
The balloon: – charged,
The wool: + charged

7. So…….
Explain what happens when you rub a balloon on your hair.

8. Insulators and Conductors
Insulators: materials that do NOT allow electrons to flow through them easily.
Insulators can be easily charged by friction as the extra electrons gained CANNOT easily escape.

9. Insulators and conductors
Conductors: materials that allow electrons to flow through them easily.
Conductors CANNOT be easily charged by friction as the extra electrons gained can easily escape.

10. Gas Station Fires
Carol said a static gas pump fire is blamed for burning her daughter so badly she needed skin grafts on her legs.
Carol had put the gas pump nozzle on automatic and re-entered her car to write a check. When her then-12-year-old daughter, wearing a sweater and jacket that may have created static electricity, reached for the nozzle, flames suddenly ignited her clothing.

11. Let me check what you know…..

12. A balloon has a negative charge when rubbed by a woollen cloth.
1 If the balloon can attract some paper scraps, which of the following cannot be the charge of paper scraps?
A Neutral B Positive
C Negative

13. A balloon has a negative charge when rubbed by woollen cloth.
2 During rubbing, what have been transferred between the woollen cloth and the balloon?
A Electrons B Protons
C Neutrons

14. What is grounding?
An object is grounded when it is connected to the earth through a connecting wire.
If a charged conductor is grounded, it will become neutral.

15. Lightening kills more than 60 people and
injures more than 400 people a year in the US
one mile every five seconds
about 20,000 C
Voltage of up to 1.2x108 volts

26. How do you protect yourself?