ELECTROSTATICS ELECTRICITY AT REST

COMPARISON OF FORCES THE ELECTRICAL FORCE IS BILLIONS OF BILLIONS OF TIMES STRONGER THAN GRAVITY ELECTRICAL REPELLING FORCE OF THE EARTH AND THE ELCTRICAL ATTRACTING FORCE OF THE EARTH ARE BALANCED SO WE FEEL NO EFFECT FROM IT.

ELECTRICAL FORCES ARISE FROM PARTICLES IN ATOMS PROTONS ATTRACT THE ELECTRONS AND HOLD THEM IN ORBIT AROUND THE NUCLEUS ELECTRONS ARE ATTRACTED TO PROTONS, BUT REPELL ELECTRONS. WHY DO THEY ATTRACT AND REPELL? NO ONE KNOWS. WE JUST SAY IT IS FUNDAMENTAL.

CHARGE THE ATTRACTING/REPELLING BEHAVIOR OF ATOMIC PARTICLES CAUSES CHARGE. BY GENERAL AGREEMENT, ELECTRONS ARE CONSIDERED TO BE NEGATIVELY CHARGED PROTONS ARE CONSIDERED TO BE POSITIVELY CHARGED NEUTRONS HAVE NO CHARGE, AND ARE NEITH ER ATTRACTED NOR REPELLED BY CHARGED PARTICLES

IMPORTANT FACTS ABOUT ATOMS EVERY ATOM HAS A POSITIVELY CHARGED NUCLEUS SURROUNDED BY A NEGATIVELY CHARGED ELECTRON. ALL ELECTRONS ARE IDENTICAL SAME MASS - 9.109 X 10-31 kg SAME CHARGE- -1.6 X 10-19 C SAME QUANTITY OF CHARGE

NUCLEUS COMPOSED OF PROTONS AND NEUTONS ALL PROTONS ARE IDENTICAL ALL NEUTRONS ARE IDENTICAL PROTON HAS ~2000 TIMES THE MASS OF AN ELECTRON. 1.673 X 10-27kg PROTON HAS A POSTIVE CHARGE EQUAL TO THE NEGATIVE CHARGE OF AN ELECTRON- 1.6 X 10-19 C NEUTRON IS CONSIDERED TO HAVE A SLIGHTLY GREATER MASS THAN A PROTON, BUT IT IS SO SMALL WE USE THE SAME VALUES IN CALCULATIONS 1.673 X 10-27kg

MORE ABOUT ATOMS ATOMS USUALLY HAVE THE SAME NUMBER OF PROTONS AS ELECTRONS WHICH PRODUCES A NET CHARGE OF ZERO.

FUNDAMENTAL RULE AT THE BASE OF ALL ELECTRICAL PHENOMENA IS: LIKE CHARGES REPEL; OPPOSITE CHARGES ATTRACT

IF LIKE CHARGES REPELL WHY DOESN’T THE NUCLEUS FLY APART? THERE ARE STRONGER FORCES THAN ELECTRICAL IN NATURE. THE NUCLEAR STRONG FORCE FORCES THE PROTONS TO STAY TOGETHER.

IF OPPOSITE CHARGES ATTRACT WHY DON’T THE PROTONS PULL THE ELECTRONS INTO THE NUCLEUS? DIFFERENT LAWS OF PHYSICS APPLY TO THE INSIDE OF AN ATOM; QUANTUM PHYSICS SAYS AN ELECTRON BEHAVES LIKE A WAVE AND HAS TO OCCUPY A CERTAIN AMOUNT OF SPACE RELATED TO ITS WAVELENGTH. THE SIZE OF AN ATOM IS SET BY THE MINIMUM AMOUNT OF ROOM THAT AN ELECTRON REQUIRES.

WHAT DOES IT MEAN TO BE ELECTRICALLY CHARGED? ELECTRONS MOVE FROM ONE LOCATION TO ANOTHER. THE NUMBER OF ELECTRONS COMPARED TO THE NUMBER OF PROTONS WILL DETERMINE THE ULTIMATE CHARGE OF THE ITEM.

ELECTRICAL EFFECTS DUE TO ELECTRICAL CHARGES MOST ITEMS ARE ELECTRICALLY NEUTRAL WHEN ELECTRONS MOVE FROM ONE LOCATION TO ANOTHER AN ELECTRICAL CHARGE CAN RESULT. DIFFERENT MATERIALS HAVE DIFFERENT AFFINITIES FOR ELECTRONS.

EXAMPLES FUR TO RUBBER SILVER TO ALUMINUM UNCOMFORTABLE FOR PEOPLE WITH SILVER FILLINGS TO CHEW ON GUM WRAPPERS. SILVER HAS A HIGHER AFFINITY FOR ELECTRONS THAN ALUMINUM AND THE MILD ACID IN THE MOUTH FACILITATES THE FLOW OF ELECTRONS WHICH WHEN TRANSMITTED TO THE NERVES OF THE TEETH IS UNPLEASANT.

CONSERVATION OF CHARGE ANOTHER CONSERVATION RULE CHARGES CAN NOT BE CREATED OR DESTROYED THEY CAN ONLY BE TRANSFERRED.

ROBERT MILLIKAN MILLIKAN OIL DROP EXPERIMENT DETERMINED THE CHARGE OF AN ELECTRON -1.6 X 10 -19 C CHARGE ON A PROTON 1.6 X 10 -19 C

ION A NEUTRAL ATOM THAT GAINS OR LOSES AN ELECTRON WILL BECOME CHARGED. BECAUSE PROTONS ARE POSITIVE, LOST ELECTRONS CAUSE A POSITIVELY CHARGED ION. GAINED ELECTRONS CAUSE A NEGATIVELY CHARGED ION.

Static Charges POWDER MONKEYS – CARRIED SACKS OF BLACK GUNPOWDER FOR CANNONS – BAREFOOTED. WHY? ELECTRONIC TECHNICIANS – WERE SPECIAL NONCONDUCTIVE CLOTHING OR SPECIAL WRIST BANDS THAT GROUND THEM. WHY? WHAT EFFECT DOES STATIC CHARGE HAVE ON YOUR DAILY LIFE? HOW CAN YOU MINIMIZE THESE EFFECTS.

WHERE DO THE ELECTRONS COME FROM THAT CAUSE STATIC CHARGE? INNERMOST ELECTRONS ARE BOUND VERY TIGHTLY TO THE NUCLEUS. OUTERMOST ELECTRONS ARE THE ELECTRONS THAT ARE TRANSFERRED FROM ONE ITEM TO ANOTHER.

EXAMPLE SOME SUBSTANCES LOSE ELECTRONS MORE EASILY RUBBER HOLDS ELECTRONS TIGHTER THAN FUR. ELECTRONS TRANSFER FROM THE FUR TO THE RUBBER WHEN RUBBED TOGETHER CAUSING THE FUR TO BE POSITIVELY CHARGED AND THE RUBBER ROD TO BE NEGATIVELY CHARGED. SILK HOLDS ELECTRONS TIGHTER THAN RUBBER. WHAT DO YOU THINK WOULD HAPPEN.

QUESTION IF YOU SCUFF YOUR FEET ON THE CARPET ARE YOU NEGATIVELY OR POSTIVELY CHARGED? ANSWER: NEGATIVELY….WHY?

COULOMB’S LAW F = k q1q2 looks like F = G m1m2 d2 d2 CHARGED PARTICLES OR OBJECTS THAT ARE SMALL COMPARED WITH THE DISTANCE BETWEEN THEM, THE FORCE BETWEEN THE CHARGES VARIES DIRECTLY AS THE PRODUCT OF THE CHARGES AND INVERSELY AS THE SQUARE OF THE DISTANCE BETWEEN THEM THE CLOSER THE CHARGES THE GREATER THE FORCE BETWEEN THEM.

UNIT COULOMB – C 1 C = 6.24 X 1018 ELECTRONS SOUNDS LIKE A LOT, BUT IT IS THE AMOUNT OF ELECTRONS THAT PASS THROUGH A 100 WATT LIGHT BULB IN ONE SECOND.

G V.S. k G – 6.7 X 10-11 Nm2/kg2 GRAVITATIONAL CONSTANT IS A SMALL NUMBER k – 9.0 X 109 Nm2/C2 COULOMB’S CONSTANT IS A LARGE NUMBER THE SIZE OF THESE CONSTANTS INDICATES THE ENORMOUS COMPARISION.

INVERSE SQUARE LAW APPLIES THE INVERSE-SQUARE LAW APPLIES TO COULOMB’S LAW. IF THE DISTANCE IS DOUBLED THE FORCE IS ¼ AS MUCH.

GRAVITY VS ELECTRICAL FORCES GRAVITY ONLY ATTRACTS ELECTRICAL FORCES EITHER ATTRACT AND REPELL

SIMILARITIES SIMILARITIES BETWEEN THESE TWO FORCES MAKE SOME PHYSICISTS THINK THEY ARE DIFFERENT ASPECT OF THE SAME THING. BOTH FORCES ARE FIELD FORCES. EINSTEIN BELIEVED THIS AND SPENT HIS LAST YEARS IN RESEARCH LOOKING FOR A THEORY THAT UNIFIED THESE TWO FORCES. THIS RESEARCH IS STILL GOING ON TODAY.

THE PRINCIPLE OF SUPERPOSITION THE RESULTANT FORCE ON ANY SINGLE CHARGE EQUALS THE VECTOR SUM OF THE INDIVIDUAL FORCES EXERTED ON THAT CHARGE BY ALL OF THE OTHER INDIVIDUAL CHARGES THAT ARE PRESENT

CONDUCTORS MATERIALS THAT ALLOWS THE ELECTRONS TO FLOW FREELY IN THE MATERIAL “LOOSE” METALS

INSULATORS MATERIALS THAT DO NOT ALLOW THEIR ELECTRONS TO FLOW FREELY “TIGHT” STYROFOAM WOOD

SEMI CONDUCTOR MATERIALS THAT CAN BE FORCED TO ACT LIKE AN INSULATOR OR A CONDUCTOR.

SUPERCONDUCTORS MATERIALS THAT ALLOW INDEFINITE FLOW OF ELECTRONS. THESE MATERIALS MUST BE AT EXTREMELY LOW TEMPERATURES…100 K

TRANSFER OF CHARGE FRICTION – CHARGING BY RUBBING TO SURFACES TOGETHER CONDUCTION – CHARGE IS TRANFERRED FROM ON MATERIAL TO ANOTHER BY TOUCHING. INDUCTION – WHEN THE ELECTRONS ON AN OBJECT THAT IS EXPOSED TO A CHARGE MOVE ON THE OBJECT TO CREATE AN OPPOSITELY CHARGED EFFECT. WHEN THE CHARGES MOVE OFF OR ONTO A CONDUCTOR BY TOUCH IT IS SAID TO BE GROUNDED.

BENJAMIN FRANKLIN INTRODUCE THE TERMS POSITIVE AND NEGATIVE AS THEY RELATE TO ELECTRICITY HELPED US UNDERSTAND GROUNDING AND INSULATION FRANKLIN’S KITE WAS NOT STRUCK BY LIGHTNING. HE WOULD BE DEAD IF IT HAD. THE KITE COLLECTED CHARGES FROM THE AIR DURING A THUNDERSTORM PROVING THAT LIGHTNING WAS A HUGE ELECTRIC SPARK.

LIGHTNING AN ELECTRIC DISCHARGE BETWEEN THE CLOUDS AND THE OPPOSITELY CHARGED GROUND OR BETWEEN OPPOSITELY CHARGED CLOUDS.

CHARGING BY POLARIZATION POLARIZATION IS THE MOVING OF CHARGES ON AN OBJECT IN SUCH A FASHION AS TO CONCENTRATE THE NEGATIVE CHARGES TO ONE SIDE AND THE POSITIVE CHARGES TO THE OTHER SIDE.

EXAMPLES BRUSHING YOUR HAIR RUBBING THE BALLOON IN YOUR HAIR AND THEN STICKING IT ON THE WALL. WATER MOLECULES ARE ELECTRIC DIPOLE, ONE SIDE IS POSITIVE AND THE OTHER SIDE IN NEGATIVE.

SUMMARY OBJECTS ARE CHARGED IN THREE WAY FRICTION CONTACT INDUCTION