# Static Electricity. + - + + + + The world is filled with electrical charges: + + + + + - - - - - - - - -

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Static Electricity

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What is this electrical potential called? Static Electricity -- - - - - - + + + + +

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.

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Common Misconceptions about “Static” Electricity Actually, the thing we call static electricity is an imbalance in the amounts of positive and negative charges found on the surface of an object.

Static electricity It is this imbalance of positive and negative charges that causes

What is Charge? Atoms are composed of protons (+), electrons (-) and neutrons. The nucleus contains the protons and neutrons and the electrons surround the nucleus.

What is Charge? Protons are much larger than electrons but have an equal and opposite charge.

Gold leaf Electroscope

Same charges repel

Unlike charges attract

Ben Franklin discovered lightening was static electricity

“Static” Electricity When you comb your hair and… … bring your comb over a pile of paper bits

Force on an Uncharged Particle Initially the paper is uncharged, but the comb polarizes the charges in the paper.

Conductors and Insulators A conductor is a substance through which electric charge flows readily. An insulator is a substance that strongly resists the flow of electric charge. Conductor insulator

Enlargement of 5 mm square computer chip.

What causes lightning? Lightning is actually just static electricity on a much larger scale. The rubbing is caused by air moving around

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

Static electricity is produced by friction between ice and water in the huge cloud Lightening

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.

Belt carries the charge that must sit on the outside of the sphere

Effect of Van De Graaf Hair is pushed apart as all the electrons on the hair repel each other.

Point Discharge Charge is more concentrated near to steep curves and points

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Point Discharge Such a strong charge the air is ionised and conducts charge + + + + + + + ++ + + + + - - + + + - - - - - - + + + + + + ++ + + ++ + +

Charging by Induction

Making a Carrier Bag Electroscope First Step: Cut a strip from a carrier bag Second Step: Lay over a pencil in a glass beaker

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