Has your sweater ever made crackling noises when you took it off? Questions!! Have you ever stuck a balloon to the wall after rubbing it on your head? Has your sweater ever made crackling noises when you took it off? Have you ever got an electric shock off your door knob? Have you ever seen lightening? Ask these questions and expect to get replies but don’t let it go on too long. Be encouraging if someone says something daft try and be positive.

All these things happen because of Static Electricity Chapter 10

What is Static Electricity? Static electricity occurs when there is a build up of electric charge on the surface of a material. It is called static electricity because the charges don’t move. The electricity we use everyday involves moving charges. You could ask them if they have built electric circuits and what happens if you break the circuit. Point out that things so longer work because the charge can’t flow.

What is charge? To understand charge we have to look at things on an extremely small scale. We have to try and understand things that we can’t even see with the most powerful microscope. Atoms!

The atom Everything we see around us everyday is made of atoms. We can’t see individual atoms because they are so small. In fact the diameter of an atom is about 0.0000000001m In the air in your classroom there are about 1500000000000000000000000000 atoms.

What is inside the atom? The atom is made of 3 sorts of particles. The electron The proton The neutron We can imagine each as a tiny little ball.

Inside an atom The protons and neutrons sit together in a lump in the middle called the nucleus. The electrons orbit around the nucleus, a bit like the planets orbiting the Sun. Most of the atom is empty space if atoms were the size of football fields, the nucleus would be a grain of sand in the middle and the electrons would be orbiting around the edge. .

Charge The electron is negatively charged. The proton is positively charged. The neutron has no charge, it is neutral.

Charge Most things have the same number of electrons and protons in them. They don’t have any overall charge. If this isn’t true interesting things can happen.

opposites attract, likes repel. How do charges behave? What do you know about magnets? 2 north poles will repel each other, but a north and a south put together will attract one another. opposites attract, likes repel. They should have covered magnets and be familiar with them. Put up the first sentence and then ask what will happen with the blue and red magnets.

How do charges behave? Exactly the same thing happens with charges. 2 positive charges put together will repel each other. Put a positive charge near a negative charge and they will attract each other. A charged object may even attract a neutral one.

Static electricity Static electricity is caused when certain materials are rubbed against each other. Electrons can be rubbed off one material and on to another. The material that has got extra electrons is now negatively charged The material which has lost electrons is positively charged.

Here’s my silly demo. The balloon will rub against the head and then pull away with the “hair” standing on end. You might need to explain what it’s supposed to be. The next few slides show what is happening to the charges. These should run automatically.

- + - + + - - + - - + + + - + - - + - +

- - + - + + - - + - - + + + - + - + - +

- - + - + + - - + - + + + - + - + - +

- - + - + + - - + - + + + - + - + +

- - + - + + - - + - + + + + - + +

- - + - + + - - + - + + + + - + Re iterate that the head an balloon each started off with the same number of positive and negative charges but the rubbing moved charges onto the balloon and off the head. The balloon is now negatively charged and the head positively charged so that because opposites attract the hairs are attracted to the balloon And because like charges repel the airs are pushed apart from each other. +

Static electricity It is this imbalance of positive and negative charges that causes: Balloons to stick to walls. Your hair to stand on end when brush your hair on a dry day. And the electric shock you sometimes get from the door handle. Briefly show the pith ball electroscope. Both balls should be attracted to the charged rod but when they touch it they will be come charged with the same charge as the rod and then repel each other. This may not work well in humid weather which gives you a chance to explain that the weather affects what happens – one teacher was amazed when I pointed out that static sparks when you take a jumper off are much worse in dry weather,

What is static electricity? When two objects rub against each other electrons transfer and build up on an object causing it to have a different charge from its surroundings. Like the shoes rubbing against the carpet. Electrons are transferred from the carpet to the shoes.

As electrons collect on an object, it becomes negatively charged As electrons collect on an object, it becomes negatively charged. As electrons leave an object it attains a positive charges. Charges interact with each other:

Often when you remove clothes from the clothes dryer, they seem to stick together. This is because some of the clothes have gained electrons by rubbing against other clothes. The clothes losing electrons become positive. The negative clothes are attracted to the positive clothes. Have you ever rubbed a balloon on your hair and stuck it on a wall? How do you think this works?

The van de Graaf generator (large silver ball) deposits electrons on the ball. When a person places their hand on the ball and the machine is turned on, electrons are transferred to and collected on the person touching the silver ball. Why do you think this machine affects the hair of the children in the picture?

What causes you to be shocked when you rub your feet across carpet? An electrical discharge is the passing of an electric current through the air from a negatively charged object to a positively charge object. This is what causes lightning!

Check out these static electricity video clips Static electricity at a gas station Van de Graaf Generator’s effect on human hair Static on Baby’s hair Kid gets static going down a slide http://video.google.com/videoplay?docid=220962315328885264&q=static+electricity&hl=en#docid=-4197277409501195467 What is a conductor and insulator? A conductor is a material which allows an electric current to pass. Metals are good conductors of electricity. An insulator is a material which does not allow an electric current to pass. Nonmetals are good conductors of electricity. Plastic, glass, wood, and rubber are good insulators

How are static charges detected?

Lightning

What causes lightning? Lightning is actually just static electricity on a much larger scale. The rubbing is caused by air moving around In thunderclouds bottom is usually negative and top is positive.

Thunder When the lightning flash happens it heats the air to a temperature 5 times hotter than the surface of the sun. This causes nearby air to expand and vibrate forming the sound we hear as thunder. They should have covered sound so they should be aware that the sounds we hear are caused by air vibrating.

Interesting facts Lightning bolts can travel at speeds of up to 60,000 miles per second. Every second around 100 bolts of lightning strike the Earth. One lightning bolt has enough electricity to power 200,000 homes. You are more likely to be struck by lightning than be eaten by a shark.

Some myths Lightning never strikes in the same place twice. False, the Empire State Building is reportedly struck 100 times a year. Wearing rubber shoes will protect me in a thunder storm. False, Lighting is too powerful to be stopped by half an inch of rubber or several hundred feet of rubber for that matter.