what is static electricity?. static electricity is… a stationary build-up of electric charge...

What is Static What is Static Electricity?Electricity?

Static Electricity is…Static Electricity is…

A stationary build-up of electric A stationary build-up of electric charge (electrons) on a material charge (electrons) on a material

Electricity that does not move (static Electricity that does not move (static vs. dynamic)vs. dynamic)

Shocking!Shocking!

http://www.youtube.com/watch?v=6Bk8Bnyjsoo

Laws of Static ChargeLaws of Static Charge

1. Opposite Charges 1. Opposite Charges AttractAttract

2. Like Charges 2. Like Charges RepelRepel

3. A charged object 3. A charged object attractsattracts an electrically an electrically

neutral object!neutral object!

Types of ChargesTypes of Charges

Most objects are neutral – Most objects are neutral – electrically unchargedelectrically uncharged

If 2 neutral objects are rubbed If 2 neutral objects are rubbed together, one becomes positively together, one becomes positively charged (loses electrons) and the charged (loses electrons) and the other becomes negatively charged other becomes negatively charged (gains electrons)(gains electrons)

Direction of electron flow called the Direction of electron flow called the “ELECTROSTATIC SERIES”“ELECTROSTATIC SERIES”

The Electrostatic SeriesThe Electrostatic Series AcetateAcetate GlassGlass WoolWool Fur/HairFur/Hair Ca, Mg, PbCa, Mg, Pb SilkSilk AluminumAluminum ZincZinc CottonCotton Paraffin waxParaffin wax EboniteEbonite PlasticPlastic C, Ni, CuC, Ni, Cu SulfurSulfur Gold, Gold,

PlatinumPlatinum

Weak hold on electrons

Strong hold on electrons

The Electrostatic SeriesThe Electrostatic Series AcetateAcetate GlassGlass WoolWool Fur/HairFur/Hair Ca, Mg, PbCa, Mg, Pb SilkSilk AluminumAluminum ZincZinc CottonCotton Paraffin waxParaffin wax EboniteEbonite PlasticPlastic C, Ni, CuC, Ni, Cu SulfurSulfur Gold, Gold,

PlatinumPlatinum

For example:A plastic comb is rubbed with wool

•The wool gives up electrons (weaker hold); becomes positively charged•The plastic comb takes electrons and becomes negatively charged

Let’s try another one…Let’s try another one… AcetateAcetate GlassGlass WoolWool Fur/HairFur/Hair Ca, Mg, PbCa, Mg, Pb SilkSilk AluminumAluminum ZincZinc CottonCotton Paraffin waxParaffin wax EboniteEbonite PlasticPlastic C, Ni, CuC, Ni, Cu SulfurSulfur Gold, Gold,

PlatinumPlatinum

Your wool sweater rubs against your cotton T-shirt…

Negative charge:• Cotton (gained electrons)

Positive charge:• Wool (lost electrons)

How to put static charge on How to put static charge on an objectan object

1. Friction1. Friction Between any two Between any two

materialsmaterials Rubbing it with Rubbing it with

somethingsomething

How to put static charge on How to put static charge on an objectan object

2. By Contact2. By ContactTouch something with a charged objectTouch something with a charged object

Positively charged object will take some Positively charged object will take some electrons from neutral object, making it electrons from neutral object, making it positive toopositive too

Negatively charged object will give Negatively charged object will give electrons to the neutral object, making it electrons to the neutral object, making it negative too negative too

Charging by ContactCharging by Contact

ConductionConduction When 2 objects When 2 objects

with different with different amounts of amounts of charge come into charge come into contactcontact

Electrons move Electrons move from one object from one object to the otherto the other

Lab Time!Lab Time!

Make your own electroscope!Make your own electroscope!

How to put static charge on How to put static charge on an objectan object

3. By Induction3. By InductionBring a charged object near a neutral Bring a charged object near a neutral object object without touching itwithout touching it

Balloon Wars!Balloon Wars!

Charging objects Charging objects Temporarily by InductionTemporarily by Induction Bringing a charged rod near the Bringing a charged rod near the

electroscope will INDUCE the same electroscope will INDUCE the same charge on the silver leafcharge on the silver leaf

Negative rod forces electrons down Negative rod forces electrons down and makes the leaf negativeand makes the leaf negative

Positive rod attracts electrons up Positive rod attracts electrons up and makes the leaf positiveand makes the leaf positive

Charging Objects Charging Objects Permanently by Permanently by

InductionInduction

Controlling Static Controlling Static ElectricityElectricity

GROUNDING:Grounding a conductor means to connect it, through some conduction material to the ground (Earth).Although Earth is not an excellent conductor, it is so huge that it can accept or give up many electrons without significant change in its charge.

GroundingGrounding

A process that removes excess A process that removes excess charge from an object.charge from an object.

Objects that need to be Objects that need to be grounded!grounded!

Appliances – to prevent dangerous Appliances – to prevent dangerous shocksshocks

Computers – sensitive to electrical Computers – sensitive to electrical surgessurges

Fuel Tanker Trucks – prevent Fuel Tanker Trucks – prevent explosions!explosions!

http://www.youtube.com/watch?v=tuZxFL9cGkI

Lightning (p. 493)Lightning (p. 493) Negative charges on the bottom of the clouds repel electrons

on the surface of the Earth, leaving the ground positively charged.

The strong attraction between the negative cloud and the positive ground pull electrons off atoms and molecules (water, ice, etc.) in the air.

Once a chain of ions (an atom that has gained or lost electrons) forms, a gigantic discharge occurs between the cloud and the ground.

The temperature of the air near a lightning bolt can reach as high as 33000 degrees Celsius, several times hotter than the sun’s surface.

If the lightning hits a person, the electrical activity can stop the heart or respiration (breathing), nearly always killing the person.

Struck by Lightning?Struck by Lightning?

http://www.youtube.com/watch?v=L1HhRAUqFqM

Lightning Rods (p. 495)Lightning Rods (p. 495) A lightning rod is charged by Induction, just like

on the sphere of the electroscope, when you brought a negatively charged rod near it.

The positively charged lightning rod is the highest point in the area.

When a lightning bolt strikes, it hits the lightning rod.

The electrons are carried around the building and into the ground by a heavy conductor, often made of braided copper wire.