static electricity chapter 20. electric force section 20.1
TRANSCRIPT
Static ElectricityChapter 20
Electric ForceSection 20.1
ElectrostaticsElectric Statics that can be
collected and held in one place.
Charged ObjectsObject that exhibits
electric interaction after rubbing is said to be charged◦Like charges: Repel
each other◦Opposite charges:
Attract each other◦Types of charge:
Matter contains both charges
A Microscopic View of ChargeAll objects contain
light, negatively charged particles◦Neutral object: positive
charge of nucleus equals the negative charge of surrounding electrons
◦Separation of charge: Occurs when two objects are rubbed together
Conductors and InsulatorsElectric
Conductor◦ Material that
allows charges to move easily
◦ Metals (ie: copper, iron, silver, gold)
Electric Insulator◦ Material through
which charge will not move easily
◦ Glass, dry wood, plastics, rubber, cloth, and dry air
Electric ForceSection 20.2
Forces on Charged Bodies There are two kinds of charges:
◦ Positive and Negative Charges exert forces on other charges at a
distance. The force is stronger when the charges are closer Like charges repel; opposite charges attract.
ElectroscopeDevice used to
determine charge.◦ Metal knob
connected by a metal stem to two thin, lightweight pieces of metal foil.
Charging by Conduction
Charging a neutral body by touching it with a charged body◦ Leaves spread apart it electroscope is
positive
Separation of Charge on Neutral Objects
Neutral object will have charges separate. ◦ Neutral object will be attracted to
the charged object.
Charging by InductionCharging an object without
touching ◦ Single object can be charged by
induction through grounding
Coulomb’s LawForce depends on
distance◦ F = 1/r2
Force depends on charge
◦ F= qAqB
Coulomb’s Law
◦ F= qAqB/ r2
Elementary Charge◦ Magnitude on electron:
1.60 X 10 -19 C◦ 1 C = 6.24 X 1018
electrons
Coulomb’s Law
Force in Newtons (N)
Coulomb’s constant: 9.0 X 109 Nm2/C2
Distance between ChargesIn Meters (m)
Charge in Coulombs (C) of object 1
Charge in Coulombs (C) of object 2