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ELECTRICITY
AND
ELECTRICITY
THE BASIC BUILDING BLOCK OF
MATTER IS THE ATOM.
ATOMS CONTAIN PROTONS,
NEUTRONS, AND ELECTRONS.
PROTONS ARE POSITIVELY CHARGED.
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ELECTRICITY
THERE ARE ONLY TWO TYPES OF
ELECTRIC CHARGES, POSITIVE AND NEGATIVE. OPPOSITE CHARGES
ATTRACT AND LIKE CHARGES REPEL.
STATIC ELECTRICITY: THE NET
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ELECTRICITY
ELECTRONS EXERT A FORCE ON
OTHER CHARGED PARTICLES BY
ELECTRICITY
CONDUCTOR: MATERIAL THAT ALLOWS
ELECTRONS TO MOVE EASILY THROUGH IT.
METALS SUCH AS COPPER AND
SILVER ARE MADE OF ATOMS THAT DON’T HOLD THEIR ELECTRONS
ELECTRICITY
INSULATOR: MATERIAL THAT DOESN’T
ALLOW ELECTRONS TO MOVE
ELECTRICITY
LIGHTNING IS A LARGE DISCHARGE OF
STATIC ELECTRICITY. WATER
DROPLET MOVEMENT IN A CLOUD RESULTS IN THE BUILD UP OF
CHARGES.
THE BOTTOM OF THE CLOUD BUILDS
ELECTRICITY
THE DIFFERENCE IN CHARGES
INCREASE AND THE ELECTRONS BECOME ATTRACTED TO THE
POSITIVE CHARGE (PROTONS) ON THE GROUND.
LIGHTNING IS BILLIONS OF
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ELECTRICITY
LIGHTNING CAN OCCUR FROM CLOUD
TO CLOUD. THE ENERGY IONIZES ATOMS IN THE ATMOSPHERE
PRODUCING HEAT.
IT CAN PRODUCE 100 MILLION VOLTS
ELECTRICITY
THE HEAT CAUSES THE AIR TO
EXPAND RAPIDLY PRODUCING
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ELECTRICITY
A NEGATIVELY CHARGED OBJECT HAS
ELECTRONS WITH MORE POTENTIAL ENERGY TO MOVE AND DO WORK
THAN AN UNCHARGED OBJECT.
ELECTRONS FLOW FROM PLACES OF
ELECTRICITY
THE DIFFERENCE IN POTENTIAL
BETWEEN TWO DIFFERENT PLACES IS POTENTIAL DIFFERENCE AND IS
MEASURED IN VOLTS. VOLTAGE IS
MEASURED BY A VOLTMETER.
VOLTAGE IS A COMPARISON OF
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ELECTRICITY
CIRCUIT: A CLOSED PATH THROUGH WHICH
ELECTRONS CAN FLOW.
CURRENT: THE FLOW OF ELECTRONS
THROUGH A WIRE OR CONDUCTOR.
THE AMOUNT OF ELECTRIC CURRENT
ELECTRICITY
IN ORDER TO KEEP CURRENT MOVING
THROUGH A CIRCUIT, THERE MUST BE A DEVICE THAT MAINTAINS A
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ELECTRICITY
DRY CELL: ELEMENT ZINC
SURROUNDING A PASTE CONTAINING
MnO2 AND NH4Cl WITH A ROD OF THE
ELEMENT CARBON DOWN THE MIDDLE.
A CHEMICAL REACTION OCCURS
ELECTRICITY
THIS CHEMICAL REACTION RESULTS IN
ELECTRONS ACCUMALATING ON THE ZINC.
THE CARBON DOESN’T TAKE PART IN
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ELECTRICITY
THE CARBON ROD BECOMES THE
POSITIVE TERMINAL AND THE ZINC IS THE NEGATIVE TERMINAL.
THE POTENTIAL DIFFERENCE
BETWEEN THESE TWO TERMINALS CAUSES CURRENT TO FLOW
ELECTRICITY
WHEN THE TWO TERMINALS ARE
CONNECTED IN THE CIRCUIT, SUCH AS PLACING A “D” BATTERY IN A
FLASHLIGHT, THE CHEMICAL REACTION BEGINS.
SO, A DRY CELL ACTS AS AN
ELECTRON PUMP BECAUSE IT HAS A POTENTIAL DIFFERENCE BETWEEN
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ELECTRICITY
WET CELLS: TWO CONNECTED PLATES
MADE OF DIFFERENT METALS OR METALLIC COMPOUNDS IN AN
ELECTROLYTE SOLUTION.
AN EXAMPLE OF A WET CELL IS A CAR
ELECTRICITY
COMMON WET CELL IS MADE UP OF LEAD
AND LEAD OXIDE PLATES IN A SULFURIC
ACID SOLUTION. SIX WET CELLS IN ONE CAR BATTERY.
CHEMICAL REACTIONS IN EACH CELL
PROVIDES A POTENTIAL DIFFERENCE OF 2 VOLTS, A TOTAL POTENTAIL OF 12 VOLTS.
AN ALTERNATOR SENDS CURRENT IN THE
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ELECTRICITY
IN A HOMES WALL SOCKET, THE
POTENTIAL DIFFERENCE ACROSS THE TWO HOLES IS 120 VOLTS. THE
ELECTRICITY
RESISTANCE: THE TENDENCY FOR A
MATERIAL TO OPPOSE THE FLOW OF ELECTRONS, CHANGING ELECTRICAL ENERGY INTO LIGHT AND HEAT.
THE AMOUNT OF RESISTANCE VARIES
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ELECTRICITY
AN EXAMPLE IS THE FILAMENT THAT
RUNS THROUGH A LIGHTBULB. AS CURRENT FLOWS THROUGH THE FILAMENT, ELECTRICAL ENERGY IS CONVERTED INTO LIGHT AND HEAT.
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ELECTRICITY
THE ELEMENT COPPER HAS LOW
RESISTANCE TO THE FLOW OF ELECTRONS AND IS A GOOD
CONDUCTOR. IT IS USED IN HOUSE WIRING BECAUSE VERY LITTLE
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ELECTRICITY
TUNGSTEN HAS A HIGH RESISTANCE
TO CURRENT AND GLOWS WHITE
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ELECTRICITY
OHMS LAW: CURRENT IN A METAL
CONDUCTOR IS DIRECTLY
ELECTRICITY
OHMS LAW:
POTENTIAL DIFFERENCE EQUALS
CURRENT TIMES RESISTANCE.
ELECTRICITY
V = I X R
A LIGHTBULB WITH A RESISTANCE OF
160 OHMS IS PLUGGED INTO A 120 VOLT OUTLET. WHAT IS THE
CURRENT?
CHOOSE THE EQUATION I = V/R
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ELECTRICITY
SERIES CIRCUIT: THE CURRENT HAS
ONLY ONE PATH TO TRAVEL ALONG. EXAMPLE IS CHRISTMAS TREE
LIGHTS… ONE FAULTY BULB CAUSES THE ENTIRE STRING OF LIGHTS TO GO OUT. THE FAULTY BULB OPENS THE
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ELECTRICITY
PARALLEL CIRCUITS: SEPARATE
BRANCHES FOR CURRENT TO MOVE THROUGH. THE CURRENT SPLITS UP TO FLOW THROUGH DIFFERENT
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ELECTRICITY
FUSE: SMALL PIECE OF METAL THAT
MELTS IF THE CURRENT BECOMES TOO HIGH AND HEATS THE CIRCUIT TOO MUCH. WHEN IT MELTS, BREAKS THE CIRCUIT PREVENTING CURRENT FROM FLOWING. A FUSE MUST BE
ELECTRICITY
CIRCUIT BREAKER: PIECE OF METAL
ELECTRICITY
ELECTRICAL POWER: THE RATE AT
WHICH ELECTRICAL ENERGY IS
CONVERTED TO ANOTHER FORM OF ENERGY.
ELECTRICAL POWER IS EXPRESSED
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ELECTRICITY
POWER EQUALS CURRENT TIMES VOLTAGE. WATTS EQUALS AMPERES TIMES VOLTS.
P = I X V
ONE WATT OF POWER IS PRODUCED WHEN
ONE AMPERE OF CURRENT FLOWS
ELECTRICITY
A CALCULATOR HAS A 0.01 AMP
CURRENT FLOWING THROUGH IT. IT OPERATES WITH A POTENTIAL
DIFFERENCE OF 9 VOLTS. HOW MUCH POWER DOES IT USE?
I = 0.01 A V = 9 V
P = 0.01 X 9
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ELECTRICITY
ELECTRICAL ENERGY IS MEASURED IN
A UNIT CALLED KILOWATT-HOUR (KWH)
ONE KILOWATT HOUR IS 1000 WATTS
OF POWER USED FOR ONE HOUR.
ENERGY = POWER X TIME
KWH = KW X h
ELECTRICITY
IF YOUR REFRIGERATOR USES 700
WATTS AND RUNS 10 HOURS EACH
DAY, HOW MUCH ENERGY (IN KWH) IS USED IN ONE DAY?
P = 700 W WHICH EQUALS 0.7 KW
t = 10 HOURS
E = P X t
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MAGNETISM
TWO OF THE FOUR FORCES ARE THE
ELECTROMAGNETIC FORCE AND GRAVITY. WHICH OF THESE TWO
MAGNETISM
MAGNETITE IS A MINERAL WITH
NATURAL MAGNETIC PROPERTIES.
2000 YEARS AGO, IT WAS DISCOVERED
THAT THIS MINERAL WOULD PULL IRON OBJECTS TOWARD IT. WHEN
MAGNETISM
MAGNETISM: A PROPERTY OF MATTER
IN WHICH THERE IS A FORCE OF ATTRACTION OR REPULSION
BETWEEN UNLIKE OR LIKE POLES.
THE MAGNETIC FORCES ARE
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MAGNETISM
ALL MAGNETS HAVE TWO
MAGNETICALLY OPPOSITE POLES,
NORTH AND SOUTH. IF A BAR MAGNET IS SUSPENDED TO TURN FREELY, THE NORTH WILL POINT NORTH.
NORTH ENDS REPEL EACH OTHER AND
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MAGNETISM
ONLY A FEW MATERIALS SHOW
STRONG MAGNETIC PROPERTIES.
PERMANENT MAGNETS ARE MADE FROM IRON, NICKEL, OR COBALT. THEY TEND TO RETAIN THEIR
MAGNETISM
BEING NEAR A MAGNET CAN CAUSE
SOME MATERIALS TO BECOME
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MAGNETISM
MAGNETIC FIELD: THE REGION
AROUND THE MAGNET WHERE MAGNETIC FORCES ACT.
A COMPASS IS A MAGNETIC NEEDLE
MAGNETISM
EARTH ACTS LIKE A GIANT BAR
MAGNET. EARTHS MAGNETIC FIELD
EXTENDS BEYOND OUR ATMOSPHERE. WHAT WE CALL THE NORTH MAGNETIC POLE IS ACTUALLY THE SOUTH POLE. THIS IS WHY THE NORTH POLE OF A COMPASS POINTS TOWARD THE
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MAGNETISM
IRON, COBALT, AND NICKEL CREATES
A MAGNETIC FIELD BECAUSE EACH ATOM EXERTS FORCE ON OTHER ATOMS. THIS CAUSES GROUPS OF ATOMS TO ALIGN THEIR MAGNETIC
POLES FACING THE SAME DIRECTION.
GROUPS OF ATOMS WITH ALIGNED
MAGNETISM
TAKE A NAIL AND RUB IT AGAINST A
PERMANENT MAGNET. THE DOMAINS (ATOMS) REALIGN TO THE MAGNETIC FIELD OF THE PERMANENT MAGNET. REMOVE THE PERMANENT MAGNET AND THE ATOMS (DOMAIN) WILL GO BACK TO ITS NORMAL RANDOM
MAGNETISM
A CURRENT MOVING THROUGH A WIRE
WILL MOVE A NEEDLE ON A COMPASS. IF THE CURRENT IS REVERSED, THE
COMPASS NEEDLE IS DEFLECTED THE OPPOSITE DIRECTION. IF THE
CURRENT STOPS, THE MAGNETIC EFFECTS STOP.
MEANING: AN ELECTRIC CURRENT
MAGNETISM
ELECTROMAGNET: A STRONG
TEMPORARY MAGNET. CONSISTS OF A COIL OF WIRE AROUND A PIECE OF
IRON. WHEN A CURRENT IS PASSED THROUGH THE WIRE, THE IRON
MAGNETISM
ELECTROMAGNETS ARE USED IN
SPEAKERS TO TURN ELECTRICAL
ENERGY INTO MECHANICAL ENERGY THAT VIBRATES SPEAKERS TO
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MAGNETISM
GALVANOMETER: AN INSTRUMENT
USED TO DETECT ELECTRIC
CURRENTS. IT CAN DO THIS BECAUSE IT USES AN ELECTROMAGNET.
TWO MAJOR GALVANOMETERS ARE
MAGNETISM
AMMETER: MEASURES ELECTRICAL
CURRENT PASSING THROUGH A CIRCUIT IN AMPERES AND SHOULD BE CONNECTED IN SERIES WITH A CIRCUIT.
VOLTMETER: MEASURES THE POTENTIAL
DIFFERENCE OF A CIRCUIT IN VOLTS AND
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MAGNETISM
ELECTRIC MOTOR: A DEVICE THAT
CHANGES ELECTRICAL ENERGY INTO MECHANICAL ENERGY.
ELECTRIC MOTORS CONTAIN AN
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MAGNETISM
ELECTROMAGNET INDUCTION:
MOVING A WIRE THROUGH A
MAGNETIC FIELD PRODUCES A
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MAGNETISM
GENERATOR: PRODUCES ELECTRIC
CURRENT BY ROTATING A LOOP OF
WIRE IN A MAGNETIC FIELD. THE WIRE LOOP IS ROTATED BY EXTERNAL
FORCES (MECHANICAL ENERGY). MOST OF THE ELECTRICITY THAT
MAGNETISM
LARGE GENERATORS AT POWER PLANTS,
ELECTROMAGNETS MADE OF A LOT OF
LOOPS OF WIRE WRAPPED AROUND IRON
AND CONNECTED TO A TURBINE, WHICH IS A LARGE WHEEL THAT ROTATES WHEN
PUSHED BY WATER, WIND, OR STEAM.
THE STEAM COMES FROM BURNING FOSSIL
MAGNETISM
DIRECT CURRENT (DC): THE CURRENT
FLOWS ONLY IN ONE DIRECTION THROUGH A WIRE.
ALTERNATING CURRENT (AC):
MAGNETISM
TRANSFORMER: INCREASES OR
DECREASES THE VOLTAGE OF
MAGNETISM
REMEMBER THAT CONDUCTING
MATERIALS ALL HAVE SOME
RESISTANCE TO THE FLOW OF ELECTRONS.
SOME OF THE ELECTRICITY MOVING
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MAGNETISM
THE MOST EFFICIENT TRANSFER OF
ELECTRICITY WOULD OCCUR IF
CONDUCTING MATERIALS HAD NO ELECTRICAL RESISTANCE.
SUPERCONDUCTORS: MATERIALS
MAGNETISM
SOME MATERIALS LOSE ALL
ELECTRICAL RESISTANCE WHEN
COOLED TO TEMPERATURES NEAR ABSOLUTE ZERO. THIS IS ZERO
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MAGNETISM
LIQUID HELIUM AND LIQUID NITROGEN
ARE USED TO MAKE MATERIALS SUPERCONDUCTORS.
BECAUSE SUPERCONDUCTORS HAVE
NO ELECTRICAL RESISTANCE, A
