ap physics unit 4: electricity static electricity greeks, such as thales of miletus, around 640 b.c....

AP Physics Unit 4: ElectricityAP Physics Unit 4: Electricity

Static ElectricityStatic Electricity

Greeks, such as Thales of Miletus, around 640 Greeks, such as Thales of Miletus, around 640 B.C. rubbed amber (fossilized tree sap) and it B.C. rubbed amber (fossilized tree sap) and it

would attract leaves.would attract leaves.

Amber is called Amber is called elektronelektron in Greek or in Greek or electrumelectrum in in Latin.Latin.


English physician and physicist William Gilbert English physician and physicist William Gilbert (1544-1603) around 1600 noted other (1544-1603) around 1600 noted other substances that could be charged.substances that could be charged.

He called stuff that gains charge He called stuff that gains charge electricselectrics and and stuff that does not gain charge stuff that does not gain charge nonelectricsnonelectrics. . He is credited for being one of the originators He is credited for being one of the originators of the word electricity.of the word electricity.


German physicist Otto von Guericke (1602-German physicist Otto von Guericke (1602-1686) around 1660’s rotated a large ball of 1686) around 1660’s rotated a large ball of

Sulfur with a crank. This was the first Sulfur with a crank. This was the first electrostatic generatorelectrostatic generator..

He called it electric fire or fluid.He called it electric fire or fluid.

He noted that static electricityHe noted that static electricity

could be could be attractiveattractive or or repulsiverepulsive..


British chemist Stephen Gray (c.1666-1736) in British chemist Stephen Gray (c.1666-1736) in 1729 noticed a cork on the end of a test tube 1729 noticed a cork on the end of a test tube

would pick up small bits of paper. When would pick up small bits of paper. When rubbing the glass tube the attraction would rubbing the glass tube the attraction would increase. Called it increase. Called it electric virtueelectric virtue and noted and noted

that it was like lightning well before Ben that it was like lightning well before Ben Franklin. Called the cork a Franklin. Called the cork a conductorconductor..


French chemist Charles Du Fay (1698-1739) in French chemist Charles Du Fay (1698-1739) in 1733 discovered the existence of two types of 1733 discovered the existence of two types of electric charge. electric charge. VitreousVitreous which was found on which was found on glass rods and glass rods and resinousresinous like that on amber. like that on amber.


American statesman and scientist Benjamin American statesman and scientist Benjamin Franklin (1706-1790) around the 1740’s Franklin (1706-1790) around the 1740’s

determined that the vitreous electric charge determined that the vitreous electric charge could cancel out the resinous charge. He could cancel out the resinous charge. He

called them called them positivepositive and and negativenegative. He called . He called neutralneutral bodies those that had the right amount bodies those that had the right amount

of electric fluid, positive had an excess and of electric fluid, positive had an excess and negative had a deficiency. He is noted for negative had a deficiency. He is noted for

inventing the lightning rod and for the famous inventing the lightning rod and for the famous kite flying experiment.kite flying experiment.


Ben probably never flew the kite himself, he was very busy Ben probably never flew the kite himself, he was very busy sailing back and forth to England and France working toward sailing back and forth to England and France working toward

American independence. He wrote excellent experimental American independence. He wrote excellent experimental journals and none mention his conducting the famous journals and none mention his conducting the famous

experiment personally.experiment personally.


Electrical Force of static electricity develops Electrical Force of static electricity develops from from like charges repellinglike charges repelling and and opposite opposite

charges attractingcharges attracting. Fundamentally this will . Fundamentally this will take place between protons, electrons or ions.take place between protons, electrons or ions.

A rubber rod is more attractive to electrons than A rubber rod is more attractive to electrons than is the fur you rub it with so it becomes is the fur you rub it with so it becomes

negative. A glass rod rubbed with silk will lose negative. A glass rod rubbed with silk will lose electrons and become positive. Notice it is electrons and become positive. Notice it is always the electrons that are moving and always the electrons that are moving and

never the protons.never the protons.


Principle of Conservation of Charge: charge is Principle of Conservation of Charge: charge is not created or destroyed, merely transferred not created or destroyed, merely transferred

from one object to another.from one object to another.


Triboelectric chargingTriboelectric charging is a type of contact is a type of contact electrification in which certain materials electrification in which certain materials

become electrically charged after they come become electrically charged after they come into contact with another different material into contact with another different material and are then separated (such as through and are then separated (such as through rubbing). The polarity and strength of the rubbing). The polarity and strength of the charges produced differ according to the charges produced differ according to the

materials, surface roughness, temperature, materials, surface roughness, temperature, strain, and other properties. strain, and other properties.

AP Physics Unit 4: ElectricityAP Physics Unit 4: ElectricityTriboelectric series:Triboelectric series:

Most positively chargedMost positively charged ((+)+)

Human skinHuman skin

LeatherLeather

Rabbit’s furRabbit’s fur

GlassGlass

QuartzQuartz

Human hairHuman hair

NylonNylon

WoolWool

LeadLead

Cat’s furCat’s fur

SilkSilk

AluminumAluminum

Paper (small positive Paper (small positive charge)charge)

No ChargeNo Charge

CottonCotton

SteelSteel

Wood (small negative Wood (small negative charge)charge)

AmberAmber

WaxWax

Rubber balloonRubber balloon

NickelNickel

CopperCopper

SulfurSulfur

PolyesterPolyester

StyrofoamStyrofoam

Plastic wrapPlastic wrap

VinylVinyl

SiliconSilicon

EboniteEbonite

Most negatively charged Most negatively charged (-)(-)


American physicist Robert Millikan (1868-1953) American physicist Robert Millikan (1868-1953) in 1909 and 1910 did his famous oil drop in 1909 and 1910 did his famous oil drop experiment to determine that charges are experiment to determine that charges are quantizedquantized. That is they occur as discrete . That is they occur as discrete

whole quantities but never fractions. Objects whole quantities but never fractions. Objects can have a charge of +1 or -2 but not +3.5can have a charge of +1 or -2 but not +3.5


LightningLightning

A spark moves through the air creating a path A spark moves through the air creating a path of ionized particles.of ionized particles.

Lightning is a very large, powerful example.Lightning is a very large, powerful example.

4 million Joules of energy. Travels at around 4 million Joules of energy. Travels at around 60000 m/s. Temperature around 30000 K.60000 m/s. Temperature around 30000 K.

100 bolts strike Earth each sec.100 bolts strike Earth each sec.

Kills about 100 Americans /yr.Kills about 100 Americans /yr.

Ionized nitrogen rains downIonized nitrogen rains down

to provide natural fertilizer.to provide natural fertilizer.


Most Most conductorsconductors are metals. Metals have “free” are metals. Metals have “free” valence electrons that weakly held and can valence electrons that weakly held and can

move from atom to atom. Known as the “sea move from atom to atom. Known as the “sea of electrons” and is called metallic bonding.of electrons” and is called metallic bonding.

InsulatorsInsulators tend to be non-metals. Electrons are tend to be non-metals. Electrons are tightly bound and are not free to move about.tightly bound and are not free to move about.

ElectrolytesElectrolytes are solutions that have ions in them are solutions that have ions in them that can carry charge.that can carry charge.


Charging by ConductionCharging by Conduction (or contact) is the charging process (or contact) is the charging process which involves the touching of a charged object to a neutral which involves the touching of a charged object to a neutral object. Upon contact, the charged object conducts some of object. Upon contact, the charged object conducts some of its excess charge to the neutral object so that both objects its excess charge to the neutral object so that both objects share (not necessarily equally) the excess charge. The share (not necessarily equally) the excess charge. The charge is conducted by the movement of electrons. Electrons charge is conducted by the movement of electrons. Electrons move from a negatively charged object to a neutral object or move from a negatively charged object to a neutral object or from a neutral object to a positively charged object. When the from a neutral object to a positively charged object. When the process is complete, both objects are charged with the same process is complete, both objects are charged with the same

type of charge.type of charge.


Charging by InductionCharging by Induction is the process of first is the process of first redistributing the charge in a body, grounding redistributing the charge in a body, grounding

the object and then removing the inducing the object and then removing the inducing agent. This does not require any contact with agent. This does not require any contact with

the object inducing the charge.the object inducing the charge.


An An electrophoruselectrophorus is a capacitive generator used to is a capacitive generator used to produce electrostatic charge via the process of produce electrostatic charge via the process of

electrostatic induction. It was invented in 1764 by electrostatic induction. It was invented in 1764 by Swedish professor Johan Wilcke but Italian scientist Swedish professor Johan Wilcke but Italian scientist

Alessandro Volta improved and popularized the Alessandro Volta improved and popularized the device in 1775, and is sometimes erroneously device in 1775, and is sometimes erroneously

credited with its invention. The word credited with its invention. The word electrophoruselectrophorus was coined by Volta from the Greek 'elektron', and was coined by Volta from the Greek 'elektron', and

'phero', meaning 'electricity bearer‘.'phero', meaning 'electricity bearer‘.


The The electroscopeelectroscope is a device which is capable is a device which is capable of detecting the presence of a charged object.of detecting the presence of a charged object.

AP Physics Unit 4: ElectricityAP Physics Unit 4: ElectricityPolarization is the process of separating opposite Polarization is the process of separating opposite

charges within an object. It is not a type of charges within an object. It is not a type of charging just a redistribution of charge.charging just a redistribution of charge.

Polarizing a surfacePolarizing a surface London dispersion forces London dispersion forces creates a temporary creates a temporary polarization.polarization.

Polarization in a Polarization in a molecule creates molecule creates permanent dipoles.permanent dipoles.


Polarization on the Earth’s surface occurs when Polarization on the Earth’s surface occurs when a negatively charged cloud induces a positive a negatively charged cloud induces a positive charge on the ground below. The result is charge on the ground below. The result is lightning.lightning.


The Leyden Jar is a device that "stores“ static The Leyden Jar is a device that "stores“ static electricity in large amounts. It was invented in electricity in large amounts. It was invented in 1745 by Pieter van Musschenbroek (1692–1745 by Pieter van Musschenbroek (1692–

1761), in Leiden, The Netherlands. It was the 1761), in Leiden, The Netherlands. It was the original form of the capacitor. original form of the capacitor.

ap physics unit 4: electricity static electricity greeks, such as thales of miletus, around 640 b.c....

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