electrostatics is the study of electrical charges that can be collected and held in one place
TRANSCRIPT
Electrostatics is the study Of electrical charges that
Can be collected and held inOne place.
If the positive charges and theNegative charges balance, an
Item is said to be neutral.
An insulator is something in Which charge does not move easily.
A conductor is something in Which charges move easily through.
The word electricity comesFrom elektron, the Greek
Word for amber.
The Greeks knew that if youRubbed the amber with aCloth, you could create
A static charge.
A very famous AmericanThat studied static electricity
Was…
Ben Franklin
Franklin learned from hisExperiments that like
Charges repel and Opposite charges attract.
But where do these positiveAnd negative charges
Come from?
That’s where J. J. ThomsonComes over to play.
Beginning in 1896, Thomson Conducted a series of
Experiments with cathodeRay tubes.
After his famous experiment,He calculated a mass to
Charge ratio of 1.76 X 10 C/g
C = Coulomb
8
Now if only there were Someone who could determineThe charge of a single electron.
Oh yeah, Robert Millikan!
In 1909, the American RobertMillikan successfully
Measured the charge ofA single electron…
1.6 X 10 C -19
And therefore, the mass of oneElectron was found to be
9.11 X 10 g-28
His experiment worked Like this:
He sprayed oil droplets intoHis apparatus, then used
X-rays to give them a Negative charge, as they Fell through, he measures
How different charges Changed the rate of falling.
As his results showed, anElectron is extremely
Light, about 2000 timesLighter than an
Atom of hydrogen!
Electrical forces must be strong,Because they easily produce Accelerations larger than the
One caused by gravity.
There are 4 major rules to Remember about electrical forces:
There are two kinds of electricalCharges, positive & negative.
Charges exert a force on other Charges over a distance.
The force is stronger when theCharges are closer together.
And
Like charges repel, oppositeCharges attract.
An electroscope is used in Experiments involving
Static electricity.
When you charge something by Conduction, you are touching the
Object to transfer electrons.
When you charge something by Induction, you are just gettingA charge close to something
To transfer charge.
Coulomb’s law states that theMagnitude of the force between
Charge qa and qb, separatedBy a distance d, is proportional
To the magnitude of the chargesAnd inversely proportional to The square of the distance.
F = K qaqb
d2
The SI unit of charge is the Coulomb (C).
One Coulomb is equal to the Charge of 1.6 X 1018 electrons.
K = 9.0 X 109
F = K qaqb
d2
Two charges are separated by3 cm. Object A has a charge of +6 μC, and B has a charge of+ 3 μC. What is the force on
Object A?
F = 180 N
