"Annenberg Media" "¶" "I'D LIKE TO TELL YOU THE STORY OF AN ACCIDENT" "THAT HAPPENED TO A CERTAIN PROFESSOR MUSHENBROOK..." "AT THE UNIVERSITY OF LEYDEN..." "IN THE YEAR 1745." "IT WAS BELIEVED AT THE TIME" "THAT ELECTRICITY MIGHT BE A KIND OF FLUID." "MUSHENBROOK WANTED TO MAKE A SOLUTION OF THE ELECTRIC FLUID" "WITH ORDINARY WATER." "A FRIEND OF HIS NAMED ANDREAS KUNIAS," "WHO ACTED AS HIS ASSISTANT," "TOOK A JAR OF WATER LIKE THIS IN HIS HAND" "AND PUT INTO IT A STOPPER WITH A LONG NAIL IN IT." "THEN HE HELD THE NAIL UP TO THE POLE" "OF AN ELECTROSTATIC GENERATING MACHINE," "SOMETHING LIKE THAT ONE," "SO THE ELECTRIC FLUID COULD RUN DOWN THE NAIL" "INTO THE WATER" "AND MAKE A SOLUTION WITH IT." "WHEN HE GRABBED THE NAIL TO PULL IT OUT OF THE WATER," "HE MADE AN ABSOLUTELY SHOCKING DISCOVERY." "MUSHENBROOK WASN'T DETERRED AT ALL." "HE JUST FOUND ANOTHER VOLUNTEER AND WENT ON WITH HIS RESEARCH." "BUT THAT DISCOVERY," "WHICH CAME TO BE KNOWN AS THE LEYDEN JAR," "TURNED OUT TO BE ONE OF THE MOST IMPORTANT" "OF THE 18th CENTURY." "BEFORE IT, ELECTRICITY WAS A MERE CURIOSITY." "AFTERWARD, IT BECAME SOMETHING GENUINELY POWERFUL." "TO APPRECIATE THE IMPACT" "THAT THE DISCOVERY HAD AT THE TIME," "YOU HAVE TO UNDERSTAND" "SOMETHING ABOUT THE WAY SCIENCE WAS DONE." "PEOPLE WHO DID EXPERIMENTS ON ELECTRICITY" "THEY WERE CALLED ELECTRICIANS" "FORMED A KIND OF FRATERNITY." "IT HAD ITS RULES AND ITS RITUALS." "NOW, THERE WERE CRUDE INSTRUMENTS AT THE TIME" "THAT COULD MEASURE THE AMOUNT OF ELECTRICITY" "THAT HAD BEEN PRODUCED." "BUT EVERY ELECTRICIAN PRIDED HIMSELF ON HIS ABILITY" "TO JUDGE THE STRENGTH OF THE ELECTRICITY" "BY FEELING THE SHOCK THAT IT PRODUCED." "NO ELECTRICIAN WOULD SEND AN EXPERIMENT OUT" "WITHOUT FIRST FEELING THE SHOCK." "BEFORE THE DISCOVERY OF THE LEYDEN JAR," "THAT WAS HARMLESS." "AFTERWARDS, IT WAS A DIFFERENT MATTER." "IT WAS NOT A GOOD TIME TO BE AN ELECTRICIAN." "MUSHENBROOK WAS THE FIRST TO DO IT." "HE LATER WROTE THAT HE WOULD NEVER DO IT AGAIN." "NEVERTHELESS, EVERY ELECTRICIAN HAD TO FEEL THE SHOCK," "WITH ONE EXCEPTION" "A GERMAN ELECTRICIAN NAMED WINKLER" "WHO GALLANTLY PERMITTED HIS WIFE TO DO IT FOR HIM." "IT TURNED OUT THAT LEYDEN JARS WERE VERY EASY TO MAKE," "BUT IT WAS VERY DIFFICULT TO UNDERSTAND WHY THEY WORKED." "PERHAPS THE MOST SHOCKING THING ABOUT THE WHOLE AFFAIR" "WAS WHERE THE EXPLANATION FINALLY CAME FROM." "IT CAME FROM AN OBSCURE PRINTER" "IN A QUAINT LITTLE VILLAGE CALLED PHILADELPHIA" "ACROSS THE ATLANTIC OCEAN." "HIS NAME, OF COURSE, WAS BENJAMIN FRANKLIN." "IN HIS OWN TIME," "HE WAS KNOWN TO HIS COUNTRYMEN" "AS THE WISEST AND THE MOST WORLDLY MAN" "THE YOUNG COLONIES COULD OFFER." "IN ENGLAND AND FRANCE," "HE WAS A LEGENDARY AND WILDLY POPULAR FIGURE." "TODAY, WE THINK OF HIM AS A STATESMAN" "WHO DABBLED IN SCIENCE." "HE WAS, IN FACT," "A SERIOUS AND VERY IMPORTANT PLAYER" "IN THE HISTORY OF SCIENCE." "AND BY FAR, HIS MOST IMPORTANT SCIENTIFIC WORK" "HAD TO DO WITH ELECTRICITY." "IN THE LATE 18th CENTURY," "PEOPLE AROUND THE WORLD" "WERE FASCINATED BY THE PHENOMENON OF ELECTRICITY." "IN JAPAN, THEY SAID THE PEOPLE FORMED A LINE AND HELD HANDS." "AND THEN A BRAVE SOUL" "TOUCHED SOMETHING CALLED A CAPACITOR." "OF COURSE, THAT MIGHT HAVE BEEN JUST A RUMOR..." "BECAUSE IN THE DAYS WHEN BENJAMIN FRANKLIN" "STROLLED THE STREETS OF PHILADELPHIA," "MOST OF THE WORLD'S SCIENTIFIC KNOWLEDGE" "ABOUT ELECTRICITY" "COULD FIT INTO A LEYDEN JAR." "PROFESSOR MUSHENBROOK AND HIS LEYDEN JARS" "DREW A LOT OF ATTENTION IN HOLLAND." "AND WITH MR. CUTHBERTSON'S DEVICES," "PROFESSOR VON MARUM" "CARRIED ON THE WORK IN THE 1780s." "BUT BEYOND THE LABORATORIES," "PARTICULARLY WHEN IT CAME TO THE FAMOUS PHILADELPHIAN," "THE BUSINESS OF ELECTRICITY COULD BE POSITIVELY PERILOUS." "IN FACT, WHEN FRANKLIN TRIED TO COOK A TURKEY" "BY ELECTROCUTION," "HE ALMOST MANAGED TO ELECTROCUTE HIMSELF." "IN HIS OWN WORDS," "FRANKLIN DESCRIBED THE DANGERS OF ELECTRICITY." ""IT SEEMED A UNIVERSAL BLOW THROUGHOUT THE BODY," ""FOLLOWED BY A VIOLENT TREMBLING IN THE TRUNK." ""A SWELLING RAISED ON MY HAND." ""MY ARMS AND BACK OF MY NECK FELT NUMB." "MY BREASTBONE WAS SORE FOR A WEEK."" "OBVIOUSLY, FRANKLIN HAD DISCOVERED" "HOW NOT TO CONDUCT ELECTRICAL EXPERIMENTS." "FOR THE RECORD, HOWEVER," "THIS ERROR WAS AS RARE AS THE MAN HIMSELF." "AFTER ALL, HE WAS THE FIRST TO PUBLISH A THEORY" "OF ELECTRIC CHARGE AND ELECTRIC FORCE." "THE DETAILS WOULD BE WORKED OUT LATER," "BUT IN MODERN TERMS, WHERE WAS FRANKLIN HEADED?" "INTHEVICINITY OFA POSITIVECHARGE," "THEELECTRICFORCEREPELS APOSITIVETESTCHARGE." "ANEXTERNALFORCEISNEEDED..." "TOPUSHTHECHARGECLOSER," "DOINGWORKAGAINST THEELECTRICFORCE" "POSITIVEWORK" "IFTHEMOTION HASA COMPONENT" "OPPOSITETO THEELECTRICFORCE..." "NEGATIVEWORK" "IFITHASACOMPONENT ALONGTHEFORCE..." "ANDNOWORKATALL" "IFTHEMOTIONISPERPENDICULAR TOTHEELECTRICFORCE." "THENETWORKISFOUND" "BYINTEGRATING THEDOTPRODUCT" "OFTHEELECTRICFORCE ANDTHEDISPLACEMENTVECTOR..." "ALONGANYPATH THROUGH THE ELECTRIC FIELD." "THATNETWORK ISEQUALTO DELTAU" "THECHANGEIN  THEPOTENTIALENERGY" "OFTHETESTCHARGE." "OFCOURSE, THEELECTRICFORCE" "ISTHETESTCHARGE TIMESTHEELECTRICFIELD," "SOTHECHANGE INPOTENTIALENERGY" "ISEQUALTO  THETESTCHARGE" "TIMES SOMETHING THAT DEPENDS" "ONLYONTHEPATH THROUGHTHEFIELD." "THATSOMETHING,DELTAV," "ISCALLEDTHEDIFFERENCE INELECTRICPOTENTIAL," "AND IT'S MEASURED IN VOLTS." "ELECTRICPOTENTIAL, ORVOLTAGE," "DEPENDSONLYON POSITION INTHEELECTRICFIELD." "THEPOTENTIALDIFFERENCE" "ISEQUALTO MINUS THEINTEGRALOF EDOT dr" "ALONGANYPATH CONNECTINGTWOPOINTS." "[THUNDER]" "A HUNDRED YEARS" "BEFORE FARADAY DISCOVERED THE ELECTRIC FIELD," "FRANKLIN SAW IT AS THE ELECTRIC ATMOSPHERE." "IN HIS THEORY," "THE ATMOSPHERE AROSE FROM A FLUID," "AN ELECTRIC FLUID," "THAT PERMEATES EVERY OBJECT ON EARTH." "EVERYTHING, IN TURN, WAS A SPONGE OF SORTS" "WHICH MIGHT SOAK UP THE ELECTRIC FLUID." "FRANKLIN SAID" "THAT WHEN AN OBJECT SOAKS UP TOO MUCH FLUID," "IT'S POSITIVELY CHARGED WITH ELECTRIC FLUID." "BUT IF AN OBJECT DOESN'T HAVE ENOUGH ELECTRIC FLUID," "THEN IT'S NEGATIVELY CHARGED." "HE SAID THAT POSITIVELY CHARGED OBJECTS" "AND NEGATIVELY CHARGED OBJECTS" "ATTRACT EACH OTHER." "BUT TWO OBJECTS THAT ARE BOTH POSITIVELY CHARGED" "REPEL EACH OTHER." "FRANKLIN'S TERMS," "POSITIVE CHARGE AND NEGATIVE CHARGE," "ARE STILL IN USE." "BUT WITH BETTER UNDERSTANDING, THEIR MEANINGS HAVE CHANGED." "TODAY IT'S UNDERSTOOD THAT THERE ARE, IN FACT," "TWO DIFFERENT TYPES OF ELECTRICITY" "POSITIVE CHARGE AND NEGATIVE CHARGE" "AND THAT ALL OBJECTS IN NATURE CONTAIN BOTH TYPES." "NEVERTHELESS, FRANKLIN HAD REALIZED, CORRECTLY," "THAT ELECTRIC CHARGE" "IS SOMETHING THAT'S NEVER CREATED NOR DESTROYED" "BUT MERELY FLOWS FROM ONE OBJECT TO ANOTHER." "SUCH FAR-REACHING INSIGHTS EARNED FRANKLIN ACCLAIM" "AS THE WORLD'S FOREMOST SCIENTIST" "IN THE FIELD OF ELECTRICITY." "BUT IT WAS THE PRINTING PRESS-- NOT SCIENCE" "THAT CREATED HIS FORTUNE," "AND IN THE PROCESS, SPREAD HIS REPUTATION." "HE'D BEEN AN APPRENTICE ON THE NEW ENGLAND COURANT," "A PUBLISHER OF THEPENNSYLVANIAGAZETTE," "AND FINALLY POORRICHARD'SALMANAC..." "WHICH MADE HIM VERY RICH, INDEED." "THOUGH HE TURNED OVER THE SHOP IN 1748," "DEVOTING HIMSELF ENTIRELY TO SCIENCE," "A CERTAIN AMOUNT OF PRINTER'S INK" "FLOWED THROUGH FRANKLIN'S VEINS FOR THE REST OF HIS LIFE." "BUT HE WAS NEVER CONTENT" "WITH MERELY READING AND WRITING ABOUT THE EVENTS OF HIS ERA." "AND WHEN IT CAME TO AMERICAN HISTORY," "FRANKLIN PREFERRED TO GO OUT AND MAKE IT HIMSELF." "BUT IF FRANKLIN WAS AN IMPORTANT PRESENCE IN THE COLONIES," "HE WAS ABSOLUTELY LEGENDARY IN EUROPE." "HE WAS AN ENORMOUSLY POPULAR FIGURE" "IN ENGLAND AND FRANCE..." "DEEPLY ADMIRED AS A STATESMAN," "A PHILOSOPHER, AND A SCIENTIST..." "WHO HAD EMERGED, INCREDIBLY," "FROM THE UNVILIZED AMERICAN COLONIES." "THROUGHOUT HIS LIFE, HE WAS ALSO REMARKABLY LUCKY." "JUST HOURS BEFORE HE WAS TO PRESENT HIS CREDENTIALS" "AT THE COURT OF LOUIS XVI," "HE DISCOVERED THAT" "THE POWDERED WIG AND FORMAL CLOTHES" "WHICH HAD BEEN PROVIDED FOR HIM" "WERE MUCH TOO SMALL." "FRANKLIN BOLDLY APPEARED" "IN HIS STREET CLOTHES AND HIS OWN HAIR" "AND INSTEAD OF BEING RIDICULED" "WAS INSTANTLY HERALDED" "AS "THE CHILD OF NATURE FROM THE BACK WOODS."" "BUT EVEN THAT WASN'T THE EXTENT OF FRANKLIN'S FAME." "HE WAS ALSO RECOGNIZED AS AN INVENTOR," "FOR A NUMBER OF GOOD REASONS" "THE LIGHTNING ROD AND THE GLASS HARMONICA..." "THE ROCKING CHAIR, THE FRANKLIN STOVE," "AND EVEN DAYLIGHT SAVINGS TIME." "ANOTHER OF HIS INVENTIONS-- BIFOCALS" "WOULD EVENTUALLY BECOME HIS TRADEMARK." "FRANKLIN WAS ALSO RELENTLESSLY OPTIMISTIC." "THROUGHOUT HIS LIFE," "HE SAW EVERYTHING AS A WONDERFUL GAME" "A SERIOUS GAME, TO BE SURE" "BUT ALSO A CHALLENGE OF LIMITLESS POSSIBILITY." "HOW DID IT FEEL" "TO FLAIL A WHIRLWIND WITH A WHIP" "OR TO CATCH LIGHTNING WITH A KITE?" "FRANKLIN WAS THE ONLY MAN ON EARTH" "WHO COULD ANSWER THOSE QUESTIONS FROM EXPERIENCE." "ON LAND AND SEA," "HE STUDIED EVERYTHING HE COULD SET HIS MIND ON." "HE WROTE OF HIS STUDIES IN GREAT DETAIL." "IN PART, FRANKLIN WAS CALLED "DOCTOR"" "BECAUSE OF HIS WRITINGS ON ILLNESS" "AND THE PRACTICE OF MEDICINE." "LIKE OTHERS, HE'D GIVEN ELECTRIC SHOCKS" "TO TREAT PALSY AND FORMS OF PARALYSIS." "HOWEVER, UNLIKE HIS MEDICAL CONTEMPORARIES," "HE'D CONCLUDED THE ONLY BENEFIT OF SHOCK TREATMENT" "CAME FROM THE EXERCISE PATIENTS GOT" "WALKING TO AND FROM HIS HOUSE FOR THEIR VISITS." "BUT FROM THE SCIENTIFIC POINT OF VIEW," "THE MOST EXCITING THING" "WAS HIS PERCEPTION OF THE ELECTRIC FLUID ITSELF." "ALTHOUGH IN HINDSIGHT" "IT'S NOT TOO HARD TO READ AN IMPERFECTION OR TWO" "IN DR. FRANKLIN'S THEORY," "IT WAS THE MOST ADVANCED OF HIS TIME." "AND TO THE EXTENT IT WAS CORRECT," "HIS ELECTRIC FLUID" "CONTAINED THE SPARKS OF THINGS TO COME." "TODAY, WHAT FRANKLIN SAW AS THE ELECTRIC ATMOSPHERE" "IS SEEN IN MODERN TERMS AS THE ELECTRIC FIELD." "AN ELECTRIC FIELD IS PRESENT AROUND ANY OBJECT" "THAT CARRIES A NET ELECTRIC CHARGE." "IF AN OBJECT'S POSITIVE CHARGE AND NEGATIVE CHARGE" "ARE BALANCED," "THE OBJECT IS ELECTRICALLY NEUTRAL" "AND IT PRODUCES VIRTUALLY NO ELECTRIC FIELD FAR AWAY." "BUT EVEN BEYOND THAT," "THE STATIC ELECTRIC FIELD INSIDE ANY PIECE OF METAL" "IS ZERO," "WHICH MEANS A TEST CHARGE WOULD FEEL NO FORCE AT ALL" "INSIDE THE PIECE OF METAL." "THAT'S TRUE EVEN IF THE METAL HAS A NET ELECTRIC CHARGE." "THAT'S BECAUSE THE CHARGE PILES UP ON THE SURFACE" "UNTIL THERE'S NO FIELD LEFT INSIDE" "TO MAKE IT MOVE." "OF COURSE, ELECTRICALLY CHARGED CONDUCTORS" "DO CREATE ELECTRIC FIELDS OUTSIDE THEMSELVES." "BUT INSIDE, THERE'S NO FIELD AT ALL." "AND BECAUSE THERE'S AN ELECTRIC FIELD" "BETWEEN TWO OPPOSITELY CHARGED PIECES OF METAL," "THERE'S BOUND TO BE A DIFFERENCE IN POTENTIAL BETWEEN THEM." "BUT SINCE THERE'S NO FIELD INSIDE," "THE POTENTIAL IS THE SAME EVERYWHERE IN THE METAL." "SO, EACH PIECE OF METAL" "IS A REGION OF CONSTANT POTENTIAL." "THE POTENTIAL DIFFERENCE BETWEEN TWO PIECES OF METAL" "DEPENDS ON HOW MUCH NET CHARGE EACH ONE HAS." "NEGATIVE CHARGE LOWERS THE POTENTIAL..." "AND POSITIVE CHARGE RAISES THE POTENTIAL." "OF COURSE, IN THE 1700s," "DR. FRANKLIN WAS IN NO POSITION" "TO GET SUCH A CLEAR PICTURE OF ELECTRIC POTENTIAL," "FOR EVEN ITS CONCEPT WAS UNKNOWN IN HIS DAY." "BUT HE DID HAVE AN ENORMOUS KNOWLEDGE OF ELECTRICITY," "WHICH HE OFTEN SHARED WITH HIS COLLEAGUES THROUGHOUT EUROPE." "AND AS THE WISEST AMERICAN," "BEN FRANKLIN ALSO PAID CONSIDERABLE ATTENTION" "TO THE GREAT MINDS OF THE PAST," "PARTICULARLY SIR ISAAC NEWTON." "FRANKLIN WAS WELL AWARE" "OF NEWTON'S THEORY OF UNIVERSAL GRAVITATION," "AND HE KNEW THE FORCE OF NEWTON'S GRAVITY" "UNITES THE UNIVERSE" "BY CAUSING MASSES TO ATTRACT EACH OTHER." "FRANKLIN WOULD HAVE LIKED TO FORMULATE A SIMILAR LAW," "A LAW OF ELECTRIC FORCE." "BUT IT DOESN'T QUITE WORK BECAUSE UNLIKE GRAVITY," "THERE ARE TWO KINDS OF ELECTRIC CHARGE." "ELECTRICAL CHARGES THAT ARE UNLIKE" "ATTRACT EACH OTHER," "AND CHARGES THAT ARE ALIKE REPEL EACH OTHER." "THAT'S ONE REASON WHY AN ORDINARY BATTERY" "HAS THE POTENTIAL TO CREATE AN ELECTRIC FIELD." "WHEN A BATTERY IS CONNECTED BETWEEN TWO PIECES OF METAL," "ITFORCESCHARGETOFLOW" "FROMONETO THEOTHER" "UNTILTHEPOTENTIALDIFFERENCE" "BETWEENTHEM" "ISEQUALTO THEVOLTAGE" "OFTHEBATTERY." "THATCREATESAN  ELECTRIC FIELD BETWEEN THEM." "IFTHEVOLTAGEISDOUBLED, SOISTHECHARGE." "SOIS THEPOTENTIALDIFFERENCE." "ANDSOIS  THEELECTRICFIELD." "INGENERAL," "THECHARGETRANSFERRED" "ISPROPORTIONALTO  THEVOLTAGEAPPLIED." "THECONSTANT OFPROPORTIONALITY,C," "ISCALLEDTHECAPACITANCE." "LONG BEFORE THERE WAS A MODERN CAPACITOR," "MUCH LESS THE MEANS AND MATHEMATICS" "TO ILLUSTRATE HOW ONE WORKS," "EVERYONE IN THE WORLD KNEW ABOUT LIGHTNING." "BUT TO DISCOVER THE ROLE OF LIGHTNING" "IN THE WORLD OF NATURAL SCIENCE," "ONE HAD TO FOLLOW BEN FRANKLIN" "INTO THE STUDY OF ELECTRICITY ITSELF." "[THUNDER]" "OF ALL THE 18th CENTURY ELECTRICIANS," "ONLY FRANKLIN HAD SEEN LIGHTNING BOLTS" "FOR WHAT THEY ARE" "HUGE SPARKS OF ELECTRICITY" "NO DIFFERENT FROM THE KNID HE COULD CREATE" "IN HIS LABORATORY." "ON PAPER, THERE WAS THE BASIS OF HIS THEORY." "FIRST, EXTEND A METAL POLE-- THE LIGHTNING ROD" "FROM THE ROOF OF A BUILDING." "THEN, PLACE A WIRE NEAR THE ROD." "IN THEORY, THE ROD WOULD DRAW SOME ELECTRICITY" "FROM THE STORMY SKY" "AND A SPARK WOULD JUMP FROM THE METAL TO THE WIRE." "PRIOR TO THE EXPERIMENT," "THESE INSTRUCTIONS HAD BEEN PRINTED IN ENGLAND." "THOMAS FRANCOIS DALIBARD" "HAD FOLLOWED THEM TO THE LETTER" "AND SUCCESSFULLY PERFORMED THE EXPERIMENT" "ON THE OUTSKIRTS OF PARIS." "OF COURSE, FRANKLIN HAD NO WAY OF KNOWING THAT" "AS HE HIMSELF STOOD UP TO FACE THE POWER OF MOTHER NATURE." "HE PUT HIS OWN THEORY INTO PRACTICE" "IN A FAR MORE DANGEROUS MANNER." "INSTEAD OF USING A LIGHTNING ROD" "TO DRAW ELECTRICITY FROM THE SKY," "HE USED A KITE" "A SIMPLE APPARATUS MADE OF TWIGS AND A SILK HANDKERCHIEF." "INSTEAD OF A SEPARATE WIRE," "HE ATTACHED A METAL KEY TO THE KITE STRING." "ON THE FATEFUL NIGHT," "HE NOTICED LOOSE THREADS" "STANDING OUT FROM THE KITE STRING." "THEN, JUST AS HE HAD BRAVELY PREDICTED," "THE SPARKS JUMPED." "AS THEY ZIPPED FROM THE KEY DIRECTLY TO HIS BARE KNUCKLE," "FRANKLIN EXPERIENCED A FEELING HE'D NEVER FORGET." "BUT IN FACT, FRANKLIN'S GREATEST DISCOVERY" "WAS NOT MADE WITH LIGHTNING BOLTS." "IT WAS MADE WITH LEYDEN JARS." "IT WAS HERE RATHER THAN IN THE STORMY SKY" "THAT BEN FRANKLIN REVOLUTIONIZED THE SCIENCE OF PHYSICS." "OTHERS ASSUMED THAT WHEN THEY CHARGED A JAR WITH ELECTRICITY," "THEY WERE ADDING LARGE AMOUNTS OF ELECTRICITY TO IT." "BUT FRANKLIN KNEW BETTER." "WITH HIS KNOWLEDGE," "HE WAS THE FIRST TO FIGURE OUT HOW A CAPACITOR WORKED." "HE REALIZED THAT THE ELECTRIC FLUID" "WAS NEITHER BEING CREATED NOR DESTROYED." "IT WAS MERELY FLOWING FROM ONE PLACE TO ANOTHER." "IN A LEYDEN JAR," "IT WAS FLOWING FROM THE CONDUCTOR INSIDE THE JAR" "TO THE CONDUCTOR ON THE OUTSIDE." "IN OTHER WORDS," "THE LEYDEN JAR WAS THE FIRST PRIMITIVE ELECTRIC CAPACITOR." "ANYTWOPIECESOFMETAL" "CANFORMACAPACITOR." "THESHAPEDOESN'TMATTER." "THETWOPIECESOFMETAL" "CANBETHEPLATES OF A PARALLEL-PLATE CAPACITOR" "ORTHEYCANBE THEINNERANDOUTERPARTS" "OFA LEYDENJAR." "THE ELECTRIC FIELD IN A PARALLEL-PLATE CAPACITOR" "IS REALLY DUE TO SHEETS OF OPPOSITE CHARGE" "FACING EACH OTHER ON THE METAL SURFACES." "THE FIELD BETWEEN THE SHEETS IS CONSTANT." "THE TWO SHEETS OF OPPOSITE CHARGE" "ATTRACT EACH OTHER AND HOLD EACH OTHER IN PLACE." "THAT'S WHY A CAPACITOR IS SUCH A USEFUL DEVICE." "IF THE VOLTAGE IS HELD CONSTANT BY A BATTERY..." "THE CHARGE, AND THEREFORE THE CAPACITANCE," "CHANGES INVERSELY" "AS THE DISTANCE BETWEEN THE PLATES" "AND IS PROPORTIONAL TO THE AREA OF THE PLATES." "FRANKLIN REALIZED" "THAT IF CAPACITORS WERE CONNECTED TOGETHER PROPERLY," "THEY WOULD CREATE A LARGER CAPACITANCE" ""PROPERLY" MEANT "IN PARALLEL."" "A SERIES OF LEYDEN JARS, ONE AFTER THE OTHER," "ACTUALLY CREATED A SMALLER CAPACITANCE." "BUT A PARALLEL BANK OF LEYDEN JARS" "PROVED TO BE AN EXCELLENT ARRANGEMENT," "AND FRANKLIN CALLED IT THE ELECTRIC BATTERY" "ANOTHER TERM THAT HAS A DIFFERENT MEANING TODAY." "BUT THE IMPORTANT THING IS NOT THE TERM." "IT'S THE IDEA." "ONLY BEN FRANKLIN REALIZED" "THAT IT DIDN'T TAKE A FANCY LEYDEN JAR" "TO HOLD ON TO ELECTRICITY." "A SIMPLE PAIR OF PARALLEL METAL PLATES WOULD DO." "DESPITE ITS OCCASIONAL INACCURACIES," "FRANKLIN'S WORK WITH ELECTRICITY WAS A SCIENTIFIC MILESTONE." "BUT EVEN SO," "BEN FRANKLIN WILL ALWAYS BE BEST REMEMBERED" "AS A STATESMAN AND A REMARKABLE PUBLIC SERVANT." "HERE IN PHILADELPHIA," "HE ESTABLISHED THE FIRST PUBLIC HOSPITAL," "THE FIRST PUBLIC LIBRARY, AND THE FIRST FIRE DEPARTMENT." "AS A DELEGATE TO THE ALBANY CONGRESS OF 1754," "HE HAD BEEN SO BOLD AS TO PROPOSE" "A UNION OF THE COLONIES." "FOR ALMOST COUNTLESS REASONS," "BENJAMIN FRANKLIN WAS AND IS A NATIONAL TREASURE," "A MONUMENT TO THE LIMITLESS PROMISE" "OF DEMOCRACY." "IN THIS ROOM," "WITH THE DILIGENCE OF A SCHOLAR" "AND THE MODERATION OF A STATESMAN," "HE SET THE COURSE AND MOLDED THE IDEALS" "FOR A NEWBORN NATION." "BUT AS A SCIENTIST," "BEN FRANKLIN WAS THE GREATEST OF THE NATURAL PHILOSOPHERS..." "NOT ONLY THEN, BUT TODAY, THROUGHOUT THE WORLD OF SCIENCE." "FRANKLIN WAS VERY, VERY CLEVER." "IT MAY BE THAT HIS CLEVEREST INVENTION" "WAS THE LIGHTNING ROD." "BUT HE HAD A COMPETITOR IN ENGLAND" "WHO ALSO INVENTED A LIGHTNING ROD." "THE TWO OF THEM DISAGREED OVER A CERTAIN DETAIL." "FRANKLIN THOUGHT THAT" "LIGHTNING RODS SHOULD HAVE POINTED ENDS ON THEM." "HIS ENGLISH COMPETITOR" "THOUGHT THAT A LIGHTNING ROD" "SHOULD HAVE ROUNDED KNOBS AT THE END." "IT TURNS OUT THAT FRANKLIN HAD THE RIGHT IDEA." "BUT AT THAT TIME," "WE WEREN'T ON GOOD TERMS WITH ENGLAND." "THERE WAS SOMETHING GOING ON CALLED THE REVOLUTIONARY WAR." "KING GEORGE III" "DECREED THAT ALL LIGHTNING RODS IN ENGLAND" "WOULD HAVE ROUNDED KNOBS." "GEORGE HAD TRIED TO CHANGE A LAW OF NATURE" "BY MEANS OF A ROYAL DECREE." "YOU CAN'T DO THAT, OF COURSE." "IT TAKES AN ACT OF PARLIAMENT." "BEFORE THE INVENTION OF THE LIGHTNING ROD," "A THUNDERSTORM WAS A TERRIFYING PHENOMENON." "THERE WAS NO PROTECTION AGAINST IT." "TYPICALLY, WHEN TOWNS KNEW A THUNDERSTORM WAS APPROACHING," "THEY'D HAVE THE CHURCH BELLS RUNG" "TO TRY TO SCARE IT AWAY." "BUT THE CHURCH TOWER" "WAS USUALLY THE HIGHEST THING IN TOWN." "SO TYPICALLY THE LIGHTNING WOULD STRIKE THE CHURCH BELL," "RUN DOWN THE DAMP BELL CORD," "AND DISPATCH THE BELL RINGER." "THE INVENTION OF THE LIGHTNING ROD" "WAS THE FIRST DEMONSTRATION" "THAT A THEORETICAL UNDERSTANDING OF SCIENCE" "COULD LEAD TO MASTERY OVER THE GREAT FORCES OF NATURE." "THE PSYCHOLOGICAL IMPACT OF THAT DISCOVERY" "IS WITH US TO THIS VERY DAY." "WE'LL GO ON WITH OUR STORY NEXT TIME." "CAPTIONING PERFORMED BY THE NATIONAL CAPTIONING INSTITUTE, INC." "CAPTIONS COPYRIGHT 1986 CALIFORNIA INSTITUTE OF TECHNOLOGY," "THE CORPORATION FOR COMMUNITY COLLEGE TELEVISION, THE ANNENBERG/CPB PROJECT" "CAPTIONING FUNDED BY THE ANNENBERG/CPB PROJECT" "PUBLIC PERFORMANCE OF CAPTIONS PROHIBITED WITHOUT PERMISSION OF NATIONAL CAPTIONING INSTITUTE" "Annenberg Media" "¶" "For information about this and other Annenberg Media programs call 1-800-LEARNER and visit us at"