ELECTRICKERY

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

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

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

Have you ever seen lightening?Have you ever seen lightening?

All these things happen because of

Static Electricity

What is Static Electricity?Static electricity occurs Static electricity occurs

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

It is called static electricity because the It is called static electricity because the charges don’t move or flow like regular charges don’t move or flow like regular electricityelectricity

What is charge?

Where do these Where do these CHARGES come from?CHARGES come from?

Atoms!

The atomEverything we see around us Everything we see around us

everyday is made of atoms.everyday is made of atoms.We can’t see individual atoms We can’t see individual atoms

because they are so small.because they are so small.

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

ChargeMost things have the same Most things have the same

number of electrons and number of electrons and protons in them – this means protons in them – this means they have no overall charge.they have no overall charge.

Charges can be MOVED Charges can be MOVED around by frictionaround by friction

Static Electricity

Only electrons can Only electrons can move.move.

Protons are “stuck” in Protons are “stuck” in the middle of atoms.the middle of atoms.

Materials that have a Materials that have a positive charge are positive charge are usually things that usually things that have “lost” electrons have “lost” electrons (not gained protons).(not gained protons).

Static ElectricityElectrostatic Electrostatic

charges build charges build up on up on insulators.insulators.

A static charge A static charge can be positive can be positive or negative.or negative.

How do charges behave? Like magnets!Like magnets!opposites attractopposites attract likes repellikes repelPut a + charge near a - charge and Put a + charge near a - charge and

they will attract each other.they will attract each other.A charged object may even attract A charged object may even attract

a neutral one.a neutral one.

Static electricityThe material that has got The material that has got

extra electrons is now (-) extra electrons is now (-) chargedcharged

The material which has The material which has lost electrons is (+) lost electrons is (+) charged.charged.

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D. ElectroscopeElectroscopeElectroscope

instrument that instrument that detects the presence detects the presence of of STATIC STATIC ELECTRICTYELECTRICTY

leaves separate leaves separate when they gain when they gain either a either a (+)(+) or or (-) (-) chargecharge

Charging by Friction:FRICTION: when two objects are rubbed togetherFor example: clothes in the dryer When two objects are rubbed together, one will GAIN electrons and the other will LOSE electrons.Only the electrons MOVE during the transfer of electric charge.

Charging by Conduction:CONDUCTION: when objects touch and an electric charge is transferred from one object to another. The neutral object will have the SAME charge as the charged object because the charges are being “shared”.For example: when you walk on a carpet and touch a metal doorknob, you will get a spark. You are transferring some of the charge to the doorknob by conduction.

Charging by Conduction

Charging by Induction:INDUCTION: when objects do not touch and an electric charge is transferred from one object to another.The neutral object will have the OPPOSITE charge as the charged object.For example: when your computer or TV screen is turned on, it begins to build a charge. When a neutral particle of dust comes near the screen, it will become attracted and stick to the screen.

Charging by Induction

Lightning

Unit 3 Static Electricity

The typical thundercloud contains areas both positively and negatively charged.

Unit 3 Static Electricity

Lightning travels from negative to positive areas.

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.

ThunderWhen 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 factsLightning 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 False, the Empire State Building is

reportedly struck 100 times a year.reportedly 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 False, Lighting is too powerful to be

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