ELECTRICITY

Have you ever stuck a balloon to the Have you ever stuck a balloon to the wall after rubbing it on your head?wall after rubbing it on your head?

Has your sweater ever made Has your sweater ever made crackling noises when you took it off?crackling noises when you took it off?

Have you ever got an electric shock Have you ever got an electric shock off your door knob?off your door knob?

Have you ever seen lightning?Have you ever seen lightning?

All these things happen because of

Static Electricity

What is Static Electricity?

Static electricity occurs when there is Static electricity occurs when there is a a build up of electric charge build up of electric charge on the on the surface of a material.surface of a material.

It is called It is called static electricitystatic electricity because because the charges don’t move.the charges don’t move.

The electricity we use everyday The electricity we use everyday involves moving charges.involves moving charges.

What is charge?

To understand charge we have to look To understand charge we have to look at things on an extremely small scale.at things on an extremely small scale.

We have to try and understand things We have to try and understand things that we can’t even see with the most that we can’t even see with the most powerful microscope.powerful microscope.

Atoms!

The atom

Everything we see around us everyday is Everything we see around us everyday is made of atoms.made of atoms.

We can’t see individual atoms because We can’t see individual atoms because they are so small.they are so small.

In fact the diameter of an atom is about In fact the diameter of an atom is about 0.0000000001m0.0000000001m

In the air in your classroom there are about In the air in your classroom there are about 1500000000000000000000000000 atoms!1500000000000000000000000000 atoms!

What is inside the atom?

The atom is made of 3 sorts of particles.The atom is made of 3 sorts of particles.

The electron The electron

The protonThe proton

The neutronThe neutron

We can imagine each as a tiny little ball. We can imagine each as a tiny little ball.

Inside an atom

The protons and The protons and neutrons sit neutrons sit together in a lump together in a lump in the middle called in the middle called the nucleus.the nucleus.

The electrons orbit The electrons orbit around the around the nucleus, a bit like nucleus, a bit like the planets orbiting the planets orbiting the Sun.the Sun.

Most of the atom is empty space; if Most of the atom is empty space; if atoms were the size of football fields, atoms were the size of football fields, the nucleus would be a grain of sand in the nucleus would be a grain of sand in the middle and the electrons would be the middle and the electrons would be orbiting around the edge. orbiting around the edge.

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Charge

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

Charge

Most things have the same number of Most things have the same number of electrons and protons in them.electrons and protons in them.

They don’t have any overall charge.They don’t have any overall charge.

If this isn’t true interesting things can If this isn’t true interesting things can happen.happen.

How do charges behave?

What do you know about magnets?What do you know about magnets?

2 north poles will repel each other, but 2 north poles will repel each other, but a north and a south put together will a north and a south put together will attract one another.attract one another.

*opposites attract, likes repel**opposites attract, likes repel*

How do charges behave?

Exactly the same thing happens with Exactly the same thing happens with charges.charges.

2 positive charges put together will 2 positive charges put together will repelrepel each other. each other.

Put a positive charge near a negative Put a positive charge near a negative charge and they will charge and they will attractattract each other. each other.

A charged object may even A charged object may even attractattract a a neutral one.neutral one.

Static electricity

Static electricity is caused when Static electricity is caused when certain materials are rubbed against certain materials are rubbed against each other.each other.

Electrons can be rubbed off one Electrons can be rubbed off one material and on to another. material and on to another.

The material that has The material that has gainedgained electrons is now electrons is now negatively chargednegatively charged

The material which has The material which has lostlost electrons electrons is is positively chargedpositively charged..

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Static electricity

It is this imbalance of positive and It is this imbalance of positive and negative charges that causes:negative charges that causes:Balloons to stick to walls.Balloons to stick to walls.Your hair to stand on end when brush Your hair to stand on end when brush

your hair on a dry day.your hair on a dry day.And the electric shock you sometimes And the electric shock you sometimes

get from the door handle.get from the door handle.

Lightning

What causes lightning?

Lightning is actually Lightning is actually just static electricity just static electricity on a much larger on a much larger scale.scale.

The rubbing is The rubbing is caused by air caused by air moving aroundmoving around

In thunderclouds In thunderclouds bottom is usually bottom is usually negative and top is negative and top is positive.positive.

Thunder

When the lightning flash happens it When the lightning flash happens it heats the air to a temperature 5 times heats the air to a temperature 5 times hotter than the surface of the sun.hotter than the surface of the sun.

This causes nearby air to expand and This causes nearby air to expand and vibrate forming the sound we hear as vibrate forming the sound we hear as thunder.thunder.

Interesting facts

Lightning bolts can travel at speeds of Lightning bolts can travel at speeds of up to 60,000 miles per second.up to 60,000 miles per second.

Every second around 100 bolts of Every second around 100 bolts of lightning strike the Earth.lightning strike the Earth.

One lightning bolt has enough One lightning bolt has enough electricity to power 200,000 homes. electricity to power 200,000 homes.

You are more likely to be struck by You are more likely to be struck by lightning than be eaten by a shark.lightning than be eaten by a shark.

Some myths

Lightning never strikes in the same place Lightning never strikes in the same place twice. twice. False, the Empire State Building is reportedly False, the Empire State Building is reportedly

struck 100 times a year.struck 100 times a year.

Wearing rubber shoes will protect me in a Wearing rubber shoes will protect me in a thunder storm.thunder storm. False, Lighting is too powerful to be stopped by False, Lighting is too powerful to be stopped by

half an inch of rubber or several hundred feet of half an inch of rubber or several hundred feet of rubber for that matter.rubber for that matter.