A. ELECTRO STATIC“ELECTRICITY AT REST”•Static electricity involves electric charges.Electric charges arise from particles of atoms.•The charges of these particles contribute to theoverall charge of any object that contains them.•Molecules – made up of atoms•Atoms – made up of positive and negativecharges
B.Atoms have zero netcharge, because they have equalnumber of electrons and neutrons.Protons in the nucleus attract theelectrons and hold them in orbit.Electrons are attracted to protonsbut electrons repel other electrons.
C. KINDS OF CHARGES•Positive charges-comes from havingmore protons than electrons•Negative charges-comes from havingmore electrons than protons.•Uncharged- Equal number of protonsand electrons
E. FACTS•Every atom has positively chargenucleus surrounded by negativelycharge electrons.•All electrons are identical; each havethe same mass and the same quantityof negative as every other electron.
F. METHODS OF CHARGING1. Charging by Friction•Transfer of electrons between the two objects that arerubbed together.•Material losing electron is positively charged and materialgaining electron is negatively charged.•Amount of gained and lost electron is equal to each other..
Triboelectric series- The ordering of substancesaccording to their affinity forelectrons
2. Charging by Induction•Method used to charge an object withoutactually touching the object to any othercharged object. •The charged object is never touched to the object being charged by induction. •The charged object does not transfer electrons to or receive electrons from the object being charged. •The charged object serves to polarize the object being charged.
Charging by Conduction Charging by conduction involves the contact of a charged object to a neutral object. In contrast to induction, where the charged object is brought near but never contacted to the object being charged, conduction charging involves making the physical connection of the charged object to the neutral object. Because charging by conduction involves contact, it is often called charging by contact.
G. THE ELECTROSCOPE . Illustrates induction. .A device that is capable of detecting the presence of a charged object. 1. KINDS
LAW OF CHARGESA.CHARLES A. COULOMB- relationship between attracting or repelling charged bodies.B. Depends on 2 things:1. Their charges 2. The distance between themC. Laws of Charges 1. Unlike charges attract 2. Like charges repelD. Charges can be created and destroyed, but only in positive-negative pairs COULOMB’S LAWA. Discovered by French Physicist Charles Coulomb in the 18th century.B. Force F between two charged spheres is inversely proportional to the square of the distance d.C. Force is directly proportional to the charges Q1 and Q2D. FORMULA•d is the distance between the charged particles•Q1 and Q2 represents the quantity of charge of the particles.•k is the proportionality constant.•Unit of charge is called COULUMB (C)•1 C is the charge of 6.24x1018 electrons.• k is a very large number. Rounded off, it equals to 9.0x10 9N•m2/C2
CONDUCTORS AND INSULATORSA. CONDUCTORS•Materials which contain movable charges that flow with minimalresistance.•Conduction- transfer of electrons from a charge object to anotherby direct contact.•Induction- movement of electrons to one part of an object by theelectric field of another object.•The outermost electrons are loosely bound and are free to travelaround.•When the conduction and valence bands overlap the atom isa CONDUCTOR and allows the free movement of electrons•EXAMPLES: Au, Ag, Cu, Al, Fe, Hg, bronze, dirty water
B. INSULATORS•Material which few or no movable charges which flowwith extremely high resistance.•The electrons are much more tightly bound to atomsand are not free to flow.•Polarization- electric charges can shift slightly to oneside when there is a change nearby•When there is a large energy level gap between theconduction and valence bands, the atom isINSULATOR; it traps electrons.• EXAMPLES: glass, rubber, oil, plastic, air, diamond,pure water