Static Electricity

Lesson 7

What is Electricity?

• All matter is made up of atoms

• Atoms are made up of: – Protons – positive charge– Neutrons – NO charge– Electrons – negative charge

• Under the right conditions, the charges of an atom can transmit energy in the form of electricity.

• When two materials are brought into close contact with each other, some of the electrons (-) move from one material onto another.

• The material that LOSES electrons becomes POSITIVELY charged.

• The material that GAINS electrons becomes NEGATIVELY charged.

Static Electricity

• When electrons move from one place to another and cause a buildup of separated positive and negative charges.

• Strips of tape gain static electricity when they are pressed against the top of a desk because they are two different materials.

Forces Between Electrical Charges• A positive charge and a

negative charge will pull each other together– Opposite charges attract

• Two positive charges or

• two negative charges will push each other apart– Like charges repel

Bill Nye Clip

• http://www.youtube.com/watch?v=Z-77IzaXGcg

What is Induced Charge?

• Rubbing a balloon on your hair

will cause a negative static

electrical charge to build up on

the balloon.

• When the balloon is held to the wall it is attracted to the wall.

• The wall must have what kind of charge?

Why?

A positive charge because

they were attracted to each

other and opposites attract.

How did the wall become positively

charged?

• When the negatively charged balloon was brought closer to the wall, it PUSHED the negative electrons in the wall away from it. The positive charges were brought to the wall’s surface and attracted the balloon to it.

• The static charge on the wall resulting from the balloon causing it’s negative and positive charges to move apart is called an induced charge.

Conductors and Insulators

• Static electricity can build up so much that it jumps to lessen the charge.– Think: you shuffle your feet along a carpet

then touch a doorknob and feel/see a spark.

How it works:• We are good conductors of electricity

– Electricity flows through easily

• The build up of electrons that has started at your feet, from rubbing them on the carpet, travels through your body making your hands negatively charged

• When your hand comes in contact with another conductor, the charge will jump from you to the other material.– If you touch a material that is a good insulator

(does not allow electrons to move easily through it) this spark will not happen.

A Good place to use insulators

• Plastic covering wires on appliances– Things you need to touch to plug in

Grounding

• If a bare wire touches the metal case of an appliance, it can become electrified with a dangerous static charge.

• A grounding wire connects the metal case to the ground so this won’t happen.

What causes lightning?Within a thundercloud there are many small

bits of ice (frozen raindrops). They bump into each other as they move

around in the air.

All of those collisions create an electric charge.

After a while, the whole cloud fills up with electrical charges.

The positive charges or protons form at the top of the cloud and the negative charges or electrons form at the bottom of the cloud.

Since opposites attract, that causes a positive charge to build up on the ground beneath the cloud.

The grounds electrical charge concentrates around anything that sticks up, such as mountains, people, or single trees. The charge coming up from these points eventually connects with a charge reaching down from the clouds and - zap - lightning strikes!

• http://www.weatherwizkids.com/weather-lightning.htm