1. Static Electricity and Lightning
9.10

2. Advantages of Static Electricity
Pollution control in industry
Removal of pollutants and dust from the air
Chemical precipitation in industry

3. Disadvantages of Static Electricity
Hairs and dust cling to clothing
Sparks creating fires and explosions

4. Lightning
Lightning occurs when the negative charges concentrated near the bottom of the cloud returned to the ground in a huge spark.
Lightning appears jagged because it follows concentrations of positive ions, of the path of least resistance.
Tall objects such as trees and skyscrapers are most likely to become conductors.

5. Lightning
Lightning rods are used to help neutralize and to conduct lightning to the ground .
Lightning and Safety:
Outdoors: stop playing golf, soccer, tennis…
Get out of pools, lakes…
Indoors: avoid taking showers or baths.
Do not handle electric appliances.
Turn off TV’s and stereos.

7. Section 9.10 Lightning
Did you know lightning is static electricity moving between two clouds or a cloud and the ground?
Lightning is the spark you might see in the sky during a thunderstorm and is five times hotter than the surface of the sun.
Even though lightning may discharge an enormous amount of electricity, because lightning lasts for such a short amount of time, the electricity cannot be trapped to be a source of energy.

8. Flashes of lightning can be very dangerous
Flashes of lightning can be very dangerous. Lightning can start fires, knock over trees and even injure or kill people.
Lightning tends to strike the highest objects such as a tall tree, telephone pole or a person who may be standing in a flat field.

9. There are many things that a person may do to stay safe if a thunderstorm is close:
Stay away from water: don't stand under an umbrella, or keep swimming;
Go indoors or into a car if possible
Stay away from telephone poles
Stay away from trees
Stay on low ground, and avoid being the tallest object
If you are in a field, crouch low
Stay away from anything metal, such as a bicycle, or golf club

10. If you are inside:
Stay away from windows and doors because of metal hinges and doorknobs.
Stay away from water taps that might conduct electricity like tubs or sinks.
Don't use and unplug any electric appliances like the television, a toaster, computer or iron.
Do not use a telephone unless it is an emergency.
Task 1: Design a safety poster telling people at least two ways of how to be safe during a thunderstorm and to avoid lightning.

11. Insulators and Conductors
In order to use electricity to our advantage, we need both insulators and conductors.
An insulator is a substance which slows the free movement of electrons from atom to atom.
Since insulators do not allow the free movement of electrons, they can encourage the build up of static charge on the surface.

12. Insulators and Conductors
A conductor is a substance in which electrons can move freely from one atom to another.
On the other hand, since conductors such as copper allow the free movement (conduction) of electrons, a static charge can never build up.

13. Static Electricity and Winter
The reason static electricity is worse in the winter is that the cold air is drier then the rest of the year and contains few water molecules.
Dry air is an insulator and does not easily pick up the charges from our body.
Therefore, any static charges that build up on our clothes and body tend to stay.

14. Common Insulators and Conductors
Good Fair Good
Conductors Conductor Insulator
Copper Carbon Fur
Gold Human body Rubber
Mercury Earth Wood
Iron Water Vapour Paper

15. This charging effect is known as induced charge separation.
Dusty
Dusty

16. + - - + - + + - - + Object 1 Charge Object 2 Glass Rubber Gold Wool
Copper
Silk + -
Calcium
Sulfur - +
Cotton
Paraffin wax