Static Electricity

Grade 9 Science

What is Electricity?....

• The word "electron" in English comes from the Greek word for amber!

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• All matter is made up of atoms, which are themselves made up of charged particles. Atoms have a nucleus consisting of neutrons and protons. They also have a surrounding "shell" that is made up electrons. Typically, matter is neutrally charged, meaning that the number of electrons and protons are the same. If an atom has more electrons than protons, it is negatively charged. If it has more protons than electrons, it is positively charged.

Triboelectric series

• Some atoms hold on to their electrons more tightly than others do. How strongly matter holds on to its electrons determines its place in the triboelectric series. If a material is more apt to give up electrons when in contact with another material, it is more positive in the triboelectric series. If a material is more apt to "capture" electrons when in contact with another material, it is more negative in the triboelectric series.

Triboelectric series • Human hands (usually too

moist, though) Very positive • Rabbit Fur • Glass • Human hair • Nylon • Wool • Fur • Lead • Silk • Aluminum • Paper • Cotton • Steel Neutral • Wood

• Amber • Hard rubber • Nickel, Copper • Brass, Silver • Gold, Platinum • Polyester • Styrene (Styrofoam) • Saran Wrap • Polyurethane • Polyethylene (like Scotch

Tape) • Polypropylene • Vinyl (PVC) • Silicon • Teflon Very negative

First law of electrostatics: Opposite charges attract, like charges repel.

Rubbing a balloon on a wool sweater creates charges on the surfaces

Rub a balloon on a wool sweater. The balloon collects negative electrical charges on its surface and the wool collects positive charges. You can then stick the balloon to the wall, which does not have an excess of either charge. The balloon will also stick to the wool, although the charges may jump back to the original material in a short time.

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Static Electricity is…

• Charges that don’t pass through an object, rather they build up on the surface

• Created by friction – one substance loses electrons the other gains electrons

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Charging by Friction

Only Electrons Move…

• Both positive and negative charges are created by the removal of electrons.

• The ease at which electrons are removed depends on the triboelectric series.

• Touching a charged object to an other object causes the charge to be lost. This is called DISCHARGING.

Ease at which Electrons are lost

your handglass

your hairnylonwoolfursilk

papercotton

hard rubberpolyester

polyvinylchloride plastic

+ve

_ve

Sparks are caused…

• When a charged object comes close to either an object of the opposite charge or a neutral object.

• The larger the build up of charge the larger the spark which jumps across the gap.

• Grounding helps to prevent the build up of charges.

Lightning rods prevent a charge from lightning causing damage to electrical appliances

Measuring the charge

• An instrument called an ELECTROSCOPE is used to measure the amount of charge.

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Charging by Induction

3 ways to charge an Object

• By friction

• By induction

• By contact.

Design an Experiment

• Knowing that a balloon rubbed on your hair becomes negatively charged

• That unlike charges attract, like charges repel

Use this information to find out the charge on various objects when they are rubbed with other objects

Create a data table to show your results

Balloon Silk Wool Cotton Acetate Rayon

Balloon repel

Silk

Wool

Cotton

Plastic

Acetate

Rayon