Presentation on theme: "Electrostatics is the study Of electrical charges that Can be collected and held in One place."— Presentation transcript:
Electrostatics is the study Of electrical charges that Can be collected and held in One place.
If the positive charges and the Negative 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 comes From elektron, the Greek Word for amber. The Greeks knew that if you Rubbed the amber with a Cloth, you could create A static charge.
A very famous American That studied static electricity Was… Ben Franklin
Franklin learned from his Experiments that like Charges repel and Opposite charges attract. But where do these positive And negative charges Come from?
That’s where J. J. Thomson Comes over to play. Beginning in 1896, Thomson Conducted a series of Experiments with cathode Ray 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 determine The charge of a single electron. Oh yeah, Robert Millikan!
In 1909, the American Robert Millikan successfully Measured the charge of A single electron… 1.6 X 10 C -19 And therefore, the mass of one Electron was found to be 9.11 X 10 g -28
His experiment worked Like this: He sprayed oil droplets into His 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, an Electron is extremely Light, about 2000 times Lighter 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 electrical Charges, positive & negative. Charges exert a force on other Charges over a distance.
The force is stronger when the Charges are closer together. And Like charges repel, opposite Charges 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 getting A charge close to something To transfer charge.
Coulomb’s law states that the Magnitude of the force between Charge q a and q b, separated By a distance d, is proportional To the magnitude of the charges And inversely proportional to The square of the distance. F = K qaqbd2qaqbd2
The SI unit of charge is the Coulomb (C). One Coulomb is equal to the Charge of 1.6 X electrons. K = 9.0 X 10 9 F = K qaqbd2qaqbd2
Two charges are separated by 3 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