ELECTRIC CURRENT A FLOW OF CHARGE

FLOW OF CHARGE POTENTIAL DIFFERENCE OR DIFFERENCE IN VOLTAGE BETWEEN THE TWO ENDS OF A WIRE. EXAMPLE: WIRE – ONE END ON THE GROUND AND THE OTHER ON THE VAN DE GRAAFF GENERATOR THAT HAS A HIGH POTENTIAL CHARGE. WHAT WILL HAPPEN?

ELECTRIC CURRENT A SUSTAINED FLOW OF CHARGE WILL ONLY HAPPEN IF A DIFFERNECE IN POTENTIAL IS MAINTAINED. CURRENT FLOWS FROM AREAS OF HIGH POTENTIAL TO AREAS OF LOW POTENTIAL.

Electric current THE FLOW OF ELECTRIC CHARGE CHARGE FLOWS THROUGH THE CIRCUIT USING THE ELECTRONS IN THE CONDUIT TO TRAVEL.

CONDUCTION ELECTRONS THE ELECTRONS THAT CHARGE USES TO TRAVEL

IONS IN FLUIDS POSITIVE AND NEGATIVE IONS MAY ADD IN THE TRANSFER OF CHARGE. WHY?

Wire PROVIDES THE PATH FOR THE CURRENT HAS NO CHARGE ITSELF

UNITS MEASURED IN AMPERES NAMED AFTER THE French physicist Andre’-Marie Ampe’re 1 AMP = 1 COULOMB/SECOND

VOLTAGE SOURCES SOMETHING THAT PROVIDES A SUSTAINED POTENTIAL DIFFERENCE

VOLTAGE SOURCES BATTERIES AND GENERATORS SUPPLY ENERGY AND SLLOW CHARGE TO MOVE

TYPES OF BATTERIES WET CELL DRY CELL CHEMICAL ENERGY CONVERTS TO ELECTRICAL ENERGY

GENERATORS CAR ALTERNATORS DAMS CONVERT MECHANICAL ENERGY TO ELECTRICAL ENERGY

ELECTROMOTIVE FORCE EMF ξ = PE/Q EMF IS THE VOLTAGE BETWEEN THE TERMINALS OF A POWER SOURCE.

VOLTAGE TO HOMES U.S. – 120 VOLTS SERVICE EUROPE – 240 VOLT SERVICE

CONFUSION CHARGE FLOWS THROUGH A CIRCUIT LIKE WATER FLOWS THROUGH A PIPE. VOLTAGE CAUSES THE CHARGE TO FLOW BUT DOES NOT FLOW ITSELF LIKE PRESSURE CAUSES WATER TO FLOW IN A PIPE. THE VOLTAGE DOES NOT FLOW JUST LIKE THE PRESSURE DOES NOT FLOW.

ELECTRIC RESISTANCE DEPENDS UPON 4 THINGS MATERIAL HOW TIGHT IS THE ATOMIC STRUCTURE TEMPERATURE R=0 OHMS AT LOW TEMP. IN SOME MATERIAL LENGTH THE LONGER THE WIRE THE GREATER THE RESISTANCE CROSS-SECTIONAL AREA THICK WIRES HAVE LESS RESISTANCE

SI UNIT FOR RESISTANCE MEASURED IN OHMS NAMED FOR GEORG SIMON OHM OHM’S LAW CURRENT = VOLTAGE/RESISTANCE I = V/R 1 AMP=1 VOLT/1 OHM

ELECTRIC SHOCK DAMAGING EFFECTS OF SHOCK RESULT FROM CURRENT PASSING THROUGH THE BODY

RESISTANCE OF THE BODY RESISTANCE OF THE BODY RANGES FROM 500,000 OHMS WITH DRY SKIN TO 100 OHMS WITH WET, SALTY SKIN. WHY SALTY?

WHAT HURTS? DRY FINGERS 12 VOLTS – NO SENSATION 24 VOLTS – SMALL SENSATION WET FINGERS 12 VOLTS – TINGLE 24 VOLTS - PAINFUL

EXAMPLE WHAT IS THE RESISTANCE OF AN ELECTRIC FRYING PAN THAT DRAWS 12 AMPS OF CURRENT WHEN CONNECTED TO A 120 V CIRCUIT?

WHY DOES ELECTRIC SHOCK DAMAGE? OVERHEATS TISSUES DISRUPTS NORMAL NERVE FUNCTION CAN IT BE HELPFUL? PUZZLE: WHAT CAUSES ELECTRIC SHOCK – CURRENT OR VOLTAGE?

DEATHS MANY PEOPLE ARE KILLED EACH YEAR FROM 120 VOLT ELECTRIC CIRCUITS IF YOU TOUCH A FAULTY 120 V LIGHT SOCKET THE POTENTIAL OF THE SOCKET AND YOUR FEET ARE DIFFERENT. THAT MAKES CURRENT FLOW.

BIRDS BIRDS SURVIVE BECAUSE THEY ONLY LAND ON ONE WIRE. WHY? WHAT WOULD HAPPEN IF THEY LANDED ON TWO DIFFERENT WIRES?

PUZZLE WHAT WOULD HAPPEN TO YOU IF YOU FELL OF A BRIDGE AND GRABBED A WIRE WITH 50,000 VOLTS ACTING ACROSS IT?

TWO TYPES OF CURRENT DC – DIRECT CURRENT ALWAYS FLOWS IN ONE DIRECTION BATTERIES PRODUCE DC AC – ALTERNATING CURRENT CURRENT CHANGES DIRECTION PRODUCED BY GENERATORS

FREQUENCY OF AC CURRENT IN THE US MOST CURRENT IS AT 60 HERTZ OR 60 CYCLES PER SECOND SOME PLACES HAVE 25,30 AND 50 HERTZ.

WHERE WAS IT POPULAR FIRST? IN THE UNITED STATES THAT IS WHY WE USE 120 VOLT SERVICE POPULAR IN EUROPE LATER. THAT IS WHY THEY USE 240 VOLT SERVICE. SOME APPLIANCES NEED 240 SERVICEOVENS, STOVE, DRYERS…ETC.

HOW DO WE GET 240 SERVICE THEN? ELECTRIC SERVICE IS PROVIDED WITH THREE WIRES. COMBINE THE TWO 120 VOLT WIRES TO GET V GROUND SERVICE POWER SOURCE

WHAT DOES THE GROUND WIRE DO? ALL WIRES IN THE HOUSE ARE ULTIMATELY CONNECTED TO A GROUND TO PREVENT SHOCKS. APPLIANCES ARE GROUNDED TO PREVENT SHOCKS. GROUND FAULT BREAKERS….???

PRIMARY USE OF ELECTRIC CURRENT TRANSPORT OF ENERGY QUIETLY FLEXIBLY CONVENIENTLY

CONVERTING A.C. TO D.C. AC – DC CONVERTER HAS A DIODE THAT ONLY ALLOWS CURRENT TO FLOW IN ONE DIRECTION. DIODE CONVERTS AC TO DC CAPACITOR SMOOTHS THE CURRENT

HOW FAST ARE THE ELECTRONS? DRIFT SPEED - SPEED OF ELECTRONS IN A CIRCUIT DRIFT SPEED IS SLOW ELECTRIC FIELD SPEED IS FAST DRIFT ELECTRIC FIELD

SOURCE OF ELECTRONS BATTERIES GENERATORS ENERGY FLOWS FROM POWER SOURCE CAUSES e- TO VIBRATE IN THE FILAMENT POWER COMPANIES SELL ENERGY YOU SUPPLY THE ELECTRONS

POWER POWER = CURRENT X VOLTAGE 1 WATT = 1 AMPERE X 1 VOLT P=IVP=E/t 1000 WATTS = 1 KILOWATT 1 KILOWATT HOUR = ENERGY ELECTRIC ENERGY = Pt

CURRENT EQUATION I = Q/t ELECTRIC CURRENT = CHARGE PASSING THROUGH A GIVEN AREA TIME INTERVAL THE CURRENT IN A LIGHT BULB IS A. HOW LONG DOES IT TAKE FOR A TOTAL CHARGE OF 1.67 C TO PASS A POINT IN THE WIRE.

capacitance The amount of energy a capacitor is able to hold. Capacitor – electrical storage unit Energy is stored between the plates Capacitance = charge/voltage C = q/v Measured in Farads Usually μF = x Farads