"Annenberg Media" "¶" "IN THE EARLY 1700s, THE WORLD OF SCIENCE" "TURNED ITS ATTENTION TO THE PROBLEM OF ELECTRICITY." "THERE WAS A GOOD REASON FOR IT." "YOU SEE, MANY SCIENTISTS" "ACTUALLY MADE THEIR LIVINGS BY GIVING LECTURES." "EITHER THEY WERE ITINERANT LECTURERS" "TRAVELING FROM TOWN TO TOWN," "SPEAKING TO WHOEVER BOUGHT A TICKET," "OR THEY WERE UNIVERSITY PROFESSORS." "EITHER WAY, THEY HAD TO ATTRACT AN AUDIENCE." "OF COURSE, TODAY," "UNIVERSITY PROFESSORS HAVE GUARANTEED AUDIENCES," "BUT THAT'S BECAUSE OF THE REQUIRED COURSE," "WHICH WAS A MUCH LATER INVENTION." "TO ATTRACT AN AUDIENCE," "THEY WANTED FLASHY, EXCITING DEMONSTRATIONS," "AND ELECTRICITY WAS JUST PERFECT FOR THAT." "A TYPICAL DEMONSTRATION" "WAS TO GET A STREET URCHIN, A LITTLE BOY." "THEY WOULD STRING HIM FROM THE CEILING BY SILK THREADS," "CHARGE HIM UP" "WITH AN ELECTROSTATIC CHARGING MACHINE," "AND DRAW SPARKS FROM HIS NOSE." "I WANTED TO SHOW YOU THAT DEMONSTRATION," "BUT ALL THE STREET URCHINS WERE TIED UP." "I'LL HAVE TO MAKE DO WITH THESE THINGS INSTEAD." "FIRST I'D LIKE TO EXPLAIN TO YOU" "A FEW SIMPLE PRINCIPLES OF ELECTRICITY." "I'M GOING TO SHOW YOU" "SOME UNUSUAL THINGS." "AT FIRST GLANCE," "THE TEACHING SCIENTIST AND THE PERFORMING MAGICIAN" "SEEM TO HAVE LITTLE IN COMMON." "FEEL FREE TO COUNT THEM." "AND YET THERE'S NO DOUBT" "THAT EACH COULD LEARN A FEW GOOD TRICKS FROM THE OTHER." "THE TWO BLACK KINGS..." "ACROSS THE STAGES OF HISTORY," "WHETHER ONE PRACTICED SCIENCE OR SORCERY" "OFTEN DEPENDED ON THE OBSERVER'S POINT OF VIEW." "THAT'S EXACTLY HALFWAY DOWN IN THE PACK." "TO FIND THAT CARD, I CUT OFF HALF THE PACK." "NO MATTER WHETHER IT WAS PURE SCIENCE OR PURE MISCHIEF," "THE ANCIENT GREEKS PURSUED IT WITH A PASSION." "THE GREEKS WERE QUICK IN SPORT AND SCIENCE ALIKE" "AND MADE A STARTLING DISCOVERY EARLY ON" "ABOUT THE NATURE OF ELECTRICITY." "IT'S A WAND MADE OF ROSIN." "I RUB THE RABBIT..." "CERTAIN MATERIALS ACT LIKE A MAGIC WAND" "WHEN RUBBED AGAINST A RABBIT'S FUR" "AND ATTRACT SMALL BITS OF MATTER." "EVENTUALLY, SCIENTISTS WOULD BE ABLE TO EXPLAIN" "EXACTLY HOW THIS PHENOMENON, ELECTRICITY, REALLY WORKS." "AND, UNLIKE THE PROFESSIONAL MAGICIAN," "THE EARLY ELECTRICIANS WERE WILLING" "TO SHARE THE SECRETS OF THEIR TRADE." "FOR INSTANCE, ONE OF THE KEYS TO ELECTRICITY" "HASN'T BEEN A SECRET" "SINCE BENJAMIN FRANKLIN TRIED HIS HAND IN THE FIELD." "HE SPREAD THE WORD," "AND IN SIMPLE ENGLISH, THIS WAS IT" "SOMETHING CALLED CHARGE, THE ELECTRIC CHARGE," "BUT WHAT WAS THE CONNECTION BETWEEN CHARGE AND FORCE?" "IN SCIENCE, AS IN MAGIC," "TIMING IS EVERYTHING," "AND IN FRANCE, CHARLES AUGUSTIN COULOUMB" "APPEARED WITH THE ANSWER." "COULOUMB'S EXPERIMENT," "WHICH REVEALED THE RELATION BETWEEN CHARGE AND FORCE," "COULD BE VERIFIED BY OTHER SCIENTISTS," "AND, MOST CONVENIENT OF ALL," "IT COULD BE DESCRIBED IN SIMPLE MATHEMATICAL TERMS." "COULOUMB'SLAWSTATES THATTHEELECTRICFORCE" "ISPROPORTIONALTO  THE PRODUCT OF THE CHARGES" "AND INVERSELY PROPORTIONAL" "TO THE SQUARE OF THE DISTANCE BETWEENTHECHARGES." "FURTHERMORE, THERE ARE TWO KINDOF CHARGES" "POSITIVE AND NEGATIVE." "ELECTRICITY ATTRACTS" "WHEN IT ACTS BETWEEN CHARGES OF DIFFERENT SIGNS." "BUT ACTING BETWEEN CHARGES THAT ARE THE SAME," "IT REPELS." "ACCORDING TO COULOUMB'S LAW..." "THEFORCETWOCHARGES EXERTONATHIRD" "IS THE VECTOR SUM OF THE FORCES EACHALONEWOULDEXERT." "INFACT,THEFORCESFROM  ANYNUMBEROF POSITIVECHARGES" "ANDNEGATIVECHARGES" "ADDTOGETHERAS VECTORS," "SO THE TOTAL FORCE IS STILL CALCULATED FROM COULOUMB'S LAW." "NOTICE THAT POSITIVE CHARGES ARESHOWNIN RED," "ANDNEGATIVECHARGES ARESHOWNIN BLUE." "ELECTRIC CHARGE BOTH EXERTS AND EXPERIENCES THE ELECTRIC FORCE," "AND THE ELECTRIC FORCE OBEYS COULOUMB'S LAW." "IT LOOKS AS SIMPLE" "AS AN 18th-CENTURY ELECTRICAL DEVICE," "AND ON THE SURFACE, THAT'S ALL THERE IS TO IT." "BUT ELECTRIC CHARGES DON'T EXIST IN ISOLATION." "INSTEAD, ELECTRICITY RESIDES IN MATTER" "THE SOLIDS, LIQUIDS, AND GASES OF THE UNIVERSE." "AND NO MATTER THE FORM IT COMES IN" "SOLID, LIQUID, OR GAS" "MATTER ITSELF IS ESSENTIALLY ELECTRICAL IN NATURE." "SO, TO UNDERSTAND ELECTRICITY," "ONE MUST FIRST COME TO TERMS WITH MATTER." "ON THE OTHER HAND, TO UNDERSTAND MATTER," "ONE MUST FIRST GRASP THE ESSENTIALS OF ELECTRICITY." "IN FACT, NEITHER CAN BE UNDERSTOOD WITHOUT THE OTHER." "IN HIS OWN STUDY, FRANKLIN BEGAN BY THINKING OF ELECTRICITY" "AS A FLUID IN SOME COMBINATION WITH MATTER." "IF THERE WAS TOO MUCH FLUID," "HE IMAGINED MATTER" "TO BE POSITIVELY CHARGED WITH ELECTRIC FLUID." "IF THERE WAS TOO LITTLE FLUID, HE IMAGINED THE MATTER" "TO BE NEGATIVELY CHARGED WITH ELECTRICITY." "THEREFORE, IN FRANKLIN'S MIND, MATTER WAS IN ITS PROPER STATE" "THAT IS, ELECTRICALLY NEUTRAL AND BALANCED" "ONLY WHEN THE RIGHT AMOUNT OF ELECTRIC FLUID IS PRESENT." "FRANKLIN WAS THE FIRST" "TO SEE ELECTRICITY IN POSITIVE AND NEGATIVE TERMS." "BUT RATHER THAN VISUALIZE TWO DIFFERENT KINDS OF CHARGE," "HE SAW EITHER TOO MUCH OR TOO LITTLE" "OF THE SAME ELECTRIC FLUID." "IN THE RIGHT HANDS," "FRANKLIN'S SINGLE ELECTRIC FLUID" "BECAME TWO KINDS" "OF ELECTRIC CHARGE." "THEY VANISH INTO THE CUP." "BY ACCUMULATING KNOWLEDGE" "PIECE BY PIECE," "SCIENTISTS WOULD PUT IT" "ALL BACK TOGETHER" "AS A SINGLE STRUCTURE" "WHOSE BASIC BUILDING BLOCKS ARE ATOMS" "HELD TOGETHER BY POSITIVE AND NEGATIVE ELECTRIC CHARGE." "AT THE CORE OF EVERY ATOM IS A NUCLEUS" "WHICH IS MADE UP OF PROTONS AND NEUTRONS." "PROTONS CONTAIN ITS POSITIVE CHARGE." "THE ATOM'S NEUTRONS HAVE NO CHARGE," "WHICH MEANS THEY'RE ELECTRICALLY NEUTRAL." "THE NUCLEUS AS A WHOLE IS SURROUNDED BY ELECTRONS," "WHICH HAVE NEGATIVE CHARGE," "AND ON THE WHOLE, EACH NEUTRAL ATOM" "HAS THE SAME NUMBER OF PROTONS AND ELECTRONS." "THE POSITIVE CHARGE OF EACH PROTON" "BALANCES THE NEGATIVE CHARGE OF EACH ELECTRON," "AND THEY'RE BOUND TOGETHER" "BY THE ATTRACTIVE ELECTRIC FORCE BETWEEN THEM." "THEY VANISH INTO THE CUP QUITE MYSTERIOUSLY." "WHEN THEY REAPPEAR..." "BUT THIS RATHER SPECIAL BALANCING ACT," "LIKE ANY OTHER ACT," "IS SOMETIMES LESS THAN PERFECT." "AS A MATTER OF FACT, NOT ALL ATOMS ARE NEUTRAL." "SOME HAVE TOO MANY ELECTRONS OR TOO FEW," "IN WHICH CASE THEY'RE CALLED IONS." "IN FACT, SODIUM IONS WITH A NET POSITIVE CHARGE" "AND CHLORINE IONS WITH A NEGATIVE CHARGE" "ARE BOUND TOGETHER BY THE ELECTRIC FORCE" "INTO CRYSTALS THAT MAKE UP ORDINARY TABLE SALT." "BUT WHETHER THEIR ATOMS ARE IONIZED OR NOT," "SOLIDS, LIQUIDS, OR GASES-- ALL MATTER IN THE UNIVERSE" "IS BOUND TOGETHER BY THE FORCE OF ELECTRICITY." "FOR INSTANCE, THEY COULD TAKE THIS DULL COPPER COIN..." "AND OF ALL THE FORMS OF MATTER," "NONE EXHIBITS THE EFFECTS OF ELECTRICITY" "MORE CLEARLY THAN METALS." "...INTO SOLID GOLD." "GOLD..." "THE STUFF THAT DREAMS ARE MADE OF." "THROUGHOUT THE AGES," "SCIENTISTS HAVE DUG DEEPLY INTO THE NATURE OF METALS," "AND IN THEIR QUEST," "THEY'VE FOUND THAT ALL METALS HAVE SIMILAR PROPERTIES." "FOR ONE THING, EVERY METAL IS MALLEABLE AND DUCTILE," "HAVING THE CAPABILITY TO CHANGE SHAPE WITHOUT BREAKING." "ANOTHER AGE-OLD PROPERTY IS LUSTER," "THE DEGREE TO WHICH A SHINY METAL REFLECTS LIGHT." "FOR A LONG TIME, THAT WAS IT." "BUT IN THE 1700s," "SCIENTISTS FOUND ANOTHER PROPERTY" "COMMON TO ALL METALS." "TODAY, IT'S CALLED CONDUCTIVITY," "THE ABILITY TO CONDUCT ELECTRICITY." "ON AN INSULATOR," "AN ELECTRIC CHARGE STAYS WHERE IT IS." "BUT ON A METAL, IT SPREADS OUT INSTANTLY," "THAT IS, THE METAL CONDUCTS ELECTRICITY." "ON A DEEPER LEVEL, THIS IS WHAT HAPPENS." "EACH ATOM OF A METAL CAN BE THOUGHT OF AS A POSITIVE ION" "WITH ONE OR TWO LOOSELY BOUND OUTER ELECTRONS." "WHEN TWO METALLIC ATOMS ARE VERY CLOSE TOGETHER," "THE OUTERMOST ELECTRONS CAN PASS EASILY FROM ONE TO THE NEXT." "AS MORE ATOMS ARE ADDED," "ELECTRONS CAN RANGE FARTHER AFIELD." "THOSE MOBILE ELECTRONS ARE KNOWN AS CONDUCTION ELECTRONS," "AND THEY GIVE METALS THEIR SPECIAL PROPERTIES." "IN THIS WAY, ALL METALS ARE ELECTRIC CONDUCTORS" "BECAUSE EVERY METAL IS LIKE A GIANT MOLECULE" "IN WHICH A NUMBER OF ELECTRONS ARE SHARED EQUALLY" "BY ALL THE ATOMS." "PICTURE IT AS A STRUCTURE OF POSITIVELY CHARGED IONS" "GLUED TOGETHER BY A FLUID OF MOBILE ELECTRONS." "IF A POSITIVE CHARGE IS BROUGHT NEAR A METAL," "IT ATTRACTS THE MOBILE, NEGATIVELY CHARGED ELECTRONS" "TOWARD ITSELF," "CAUSING THEM TO PILE UP AT THE NEAREST SURFACE." "THE RESULT IS TO LEAVE NET POSITIVE IONS," "UNBALANCED BY ELECTRONS," "AT THE FAR SURFACE." "THE CLOSER AN ELECTRIC CHARGE GETS TO A METAL," "THE MORE CHARGE OF THE OPPOSITE SIGN" "BUILDS UP ON THE NEAR SURFACE" "AND MORE CHARGE OF THE SAME SIGN" "IS LEFT ON THE REST OF THE SURFACE." "AND NOW AN AMAZING LITTLE BOX!" "THESE PROPERTIES ARE USED IN AN INSTRUMENT OF SCIENCE" "THAT MAY SEEM LIKE MAGIC." "IT'S CALLED A GOLD-LEAF ELECTROSCOPE." "WHEN AN ELECTRIC CHARGE IS BROUGHT NEAR THE METAL DISK," "THE GOLD LEAF MOVES AWAY FROM THE ROD." "FLOAT!" "A POSITIVE CHARGE NEAR THE TOP ATTRACTS NEGATIVE CHARGES," "LEAVING POSITIVE CHARGE AT THE OTHER END OF THE METAL ROD," "AND THE GOLD LEAF IS LEFT WITH THE SAME KIND OF CHARGE." "AND, OF COURSE," "WITH THE SAME KIND OF CHARGE," "THE ROD REPELS THE GOLD LEAF." "WHEN THE WAND IS REMOVED, THE LEAF FALLS BACK DOWN" "UNLESS CHARGE IS TRANSFERRED TO THE DISK" "BY PHYSICAL CONTACT." "FLOAT." "STAY." "PHYSICAL CONTACT LEAVES THE ROD AND GOLD LEAF" "WITH A NET EXCESS CHARGE," "AND THE LEAF STAYS UP." "BUT IT FALLS AGAIN AT A TOUCH OF THE HAND." "DOWN." "THE HAND, WHICH IS ITSELF A CONDUCTOR," "CONNECTS THE POST TO THE ELECTROSCOPE CASE." "WHERE ON EARTH DID THAT EXTRA CHARGE GO?" "THE ELECTROSCOPE CASE IS IN CONTACT WITH THE EARTH," "WHICH IS A VERY BIG CONDUCTOR IN ITS OWN RIGHT." "WHEN CONTACT IS MADE," "THE ELECTROSCOPE, LIKE ANY OTHER CONDUCTOR," "SHARES ITS CHARGE, RELEASING MOST OF IT INTO THE LARGER BODY." "ALTHOUGH IN REALITY ONLY NEGATIVE ELECTRONS" "FLOW FROM ONE PLA TO ANOTHER," "THE EFFECT IS EXACTLY AS IF POSITIVE CHARGE FLOWED" "IN THE OPPOSITE DIRECTION." "THIS IS CALLED GROUNDING AN ELECTRIC CONDUCTOR," "OR SIMPLY GROUNDING." "AND, FOR ALL PRACTICAL PURPOSES, WHEN IT HAPPENS," "THE CONDUCTOR BECOMES ELECTRICALLY NEUTRAL." "IF THAT'S THE CASE," "HOW DOES ANYTHING EVER GET CHARGED IN THE FIRST PLACE?" "ONE WAY IS FRICTION, WHICH IS NO SURPRISE TO ANYONE" "WHO'S WALKED ACROSS A DRY CARPET AND RECEIVED A SHOCK." "BUT THERE ARE MORE EFFECTIVE WAYS" "TO CHARGE BY FRICTION." "I'VE BUILT UP A STATIC CHARGE" "SO THAT THE PAPER CLINGS TO THE ROD." "IN THE 18th CENTURY, ELECTRICIANS DEVISED MACHINES" "THAT ACCUMULATED ELECTRIC CHARGE BY RUBBING A SPINNING INSULATOR," "SUCH AS GLASS." "AND NOW A LITTLE SOMETHING YOU'LL FIND ELECTRIFYING." "THIS IS COURTESY OF MY GOOD FRIEND MR. VAN DE GRAAFF." "IN THE 20th CENTURY," "ROBERT VAN DE GRAAFF USED THE SAME PRINCIPLE" "CHARGES STAY PUT ON THE SURFACE OF AN INSULATOR" "TO COME UP WITH A NEW TWIST." "DOWN HERE, AN INSULATING BELT PICKS UP ELECTRIC CHARGE." "THE CONVEYOR BELT CARRIES THE CHARGE UPWARD" "TO THE TOP OF THE MACHINE," "WHERE THE CHARGE IS TRANSFERRED TO THE INSIDE OF THE METAL DOME." "SINCE METAL IS A CONDUCTOR, THE CHARGE SPREADS OUT" "AND, IN THE PROCESS, BUILDS UP" "UNTIL IT ESCAPES BY MEANS OF A SPARK" "AND MAKES ITS WAY BACK TO ITS OLD HOME, THE GROUND." "BUT VAN DE GRAAFF'S MACHINE HAD MUCH MORE POTENTIAL" "THAN A MERE TRICK" "TO SPARK THE INTEREST OF A CABARET AUDIENCE." "IN FACT, ITS MAIN FEATURE" "TRANSFERRING ELECTRIC CHARGE BY CONVEYOR BELT" "IS THE PRINCIPLE BEHIND ONE OF THE MOST IMPORTANT DEVICES" "OF THE MODERN NUCLEAR PHYSICS LABORATORY." "THIS STURDY YELLOW CHAMBER," "BY CONTAINING GAS AT HIGH PRESSURE," "IS DESIGNED PRECISELY TO PREVENT SPARKS FROM FLYING." "INSIDE, WITH NO SPARKS TO DISCHARGE IT," "AN ENORMOUS POSITIVE CHARGE IS BUILT UP BY CONVEYOR BELT" "ON THE MAIN TERMINAL AT THE CENTER." "IN THE MEANTIME, A NEGATIVELY CHARGED ION" "IN THIS CASE, A CARBON ATOM WITH AN EXTRA ELECTRON" "IS BEING PREPARED FOR AN EXTRAORDINARY JOURNEY." "STARTED ON ITS WAY BY OTHER NEGATIVE CHARGES..." "STEERED AROUND A CORNER BY ONE MAGNETIC FIELD," "AND KEPT AT THE CENTER OF THE TUBE" "BY ANOTHER MAGNETIC FIELD," "IT SOON FEELS THE ATTRACTIVE FORCE" "DUE TO THE POSITIVE CHARGE ON THE MAIN TERMINAL." "ACCELERATED BY THE ELECTRIC FORCE" "BETWEEN THE NEGATIVE ION AND THE POSITIVE TERMINAL," "THE ION STREAKS FORWARD AT HIGH SPEED" "UNTIL A COLLISION WITH GAS ATOMS STRIPS SOME ELECTRONS," "CHANGING THE ION FROM NEGATIVE TO POSITIVE." "ACCELERATED ONCE AGAIN BY THE ELECTRIC FORCE," "THE ION CONTINUES ON TO ITS DESTINY," "IN THIS CASE, A NUCLEAR COLLISION" "BETWEEN CARBON AND A TARGET OF HELIUM." "THIS EXTRAORDINARY MACHINE IS CALLED" "TANDEM VAN DE GRAAFF ACCELERATOR" "BECAUSE IT USES THE ENORMOUS CHARGE" "BUILT UP BY THE VAN DE GRAAFF GENERATOR" "NOT ONCE, BUT TWICE." "OF COURSE, USING THE POSITIVE CHARGE TWICE" "IS A TRICK OF SORTS," "BUT IT'S STILL STRICTLY SCIENCE," "NOT MAGIC." "ALTHOUGH ROBERT VAN DE GRAAFF'S CONVEYOR BELTS" "ARE AN EXCELLENT WAY TO BUILD UP CHARGE," "MOTHER NATURE'S ALWAYS HAD A FEW TRICKS OF HER OWN" "ALONG THOSE LINES." "SINCE THE BEGINNING OF TIME," "THUNDERSTORMS HAVE INVOLVED HUGE BUILD-UPS AND RELEASES" "OF ELECTRIC CHARGE." "SCIENTISTS BELIEVE THE MECHANISM INVOLVES FRICTION" "BETWEEN ICE PARTICLES IN THE CLOUDS." "BUT FRICTION ISN'T THE ONLY WAY CHARGE CAN BE TRANSFERRED." "THIS METAL PLATE SEEMS TO BE CHARGED" "JUST BY TOUCHING IT." "IT'S NOT MAGIC," "BUT THERE IS A TRICK TO IT." "IF A POSITIVE CHARGE IS BROUGHT NEAR A METAL," "NEGATIVE CHARGE WILL RUSH TOWARD IT," "AND POSITIVE CHARGE IS LEFT BEHIND ON THE OTHER SIDE." "THEN, IF THE METAL IS MOMENTARILY GROUNDED," "CHARGE FLOWS BETWEEN THE METAL AND THE EARTH," "LEAVING THE METAL NEGATIVELY CHARGED" "WHEN CONTACT IS BROKEN." "BUT IF I CHARGE THE STAND..." "YOU'LL NOTICE AN INCREDIBLE REACTION." "THAT PRINCIPLE'S CALLED CHARGING BY INDUCTION," "AND IT CAN SEEM MAGICAL TO AN AUDIENCE" "THAT DOESN'T REALIZE THERE ARE ELECTRIC CHARGES" "TRAPPED INSIDE THE PLASTIC SHEET." "THAT'S WHY THE METAL PLATE SEEMS TO HAVE BEEN CHARGED" "JUST BY TOUCHING IT." "THE TRICK IS THAT TOUCHING THE PLATE" "MOMENTARILY CONNECTS IT TO THE GROUND," "AND THAT'S WHAT LEAVES IT ELECTRICALLY CHARGED." "THIS IS NOT H.G. WELLS' TIME MACHINE." "IT IS INSTEAD KNOWN AS THE WIMSHURST GENERATOR," "ONE OF SEVERAL EARLY WAYS OF MAKING ELECTRICITY." "WATCH CLOSELY." "INVENTED IN 1880 BY JAMES WIMSHURST," "AN ENGLISH ENGINEER," "THIS FLASHY MACHINE FEATURES COUNTER-ROTATING DISKS" "ON WHICH METAL TABS ARE CHARGED BY INDUCTION," "WITH CONTACT BEING MADE AND BROKEN" "THROUGH METAL BRUSHES." "AS THE WHEELS ROTATE, ELECTRIC CHARGE BUILDS UP" "UNTIL A MINIATURE BOLT OF LIGHTNING" "RELIEVES THE MOUNTING TENSION." "ONE OF THE SECRETS OF THE WIMSHURST MACHINE'S SUCCESS" "IS THE DEVICE IT USES TO STORE UP ELECTRIC CHARGE." "IT'S THE LEIDEN JAR," "NAMED AFTER ITS BIRTHPLACE AT THE UNIVERSITY OF LEIDEN." "THE PRINCIPLE BEHIND THE LEIDEN JAR" "IS AS SIMPLE AS THE DEVICE ITSELF." "IN A LEIDEN JAR, THE INSIDE AND OUTSIDE ARE METALS," "SEPARATED BY THE GLASS OF THE JAR." "IF THE INSIDE IS CHARGED WHILE THE OUTSIDE IS GROUNDED," "THE NET RESULT IS EQUAL AMOUNTS OF OPPOSITE CHARGE" "ON BOTH SIDES OF THE INSULATOR," "AND THOSE OPPOSITE CHARGES ARE HELD FIRMLY IN PLACE" "BY THE ELECTRIC FORCE BETWEEN THEM." "THE LEIDEN JAR WAS ONE OF THE BEST TRICKS" "OF THE 18th-CENTURY ELECTRICIANS," "WHO WERE OFTEN ACCOMPLISHED PERFORMERS." "OF COURSE, THE MODERN MAGICIAN HAS A FEW TRICKS OF HIS OWN," "AND THE MAGICIAN'S TRICKS ILLUSTRATE, ABOVE ALL," "THE GREATEST DIFFERENCE BETWEEN MAGIC AND SCIENCE." "THE MAGICIAN'S ART IS TO CONFOUND THE SENSES" "AND CREATE MYSTERY," "BUT THE SCIENTIST'S TASK IS TO EXPAND THE SENSES" "AND SOLVE MYSTERIES." "A LIVE HAIR!" "IF THIS DISAPPOINTED YOU, MAYBE I CAN TRANSFORM IT" "INTO THE KIND OF HARE YOU WERE EXPECTING." "NEVERTHELESS," "MAGICIANS DO HAVE ONE THING IN COMMON" "WITH THE MODERN PROFESSOR." "LADIES AND GENTLEMEN, A LIVE HARE!" "THEY BOTH TRY TO ENTERTAIN," "AT LEAST, TO THE BEST OF THEIR ABILITIES." "I WANTED TO SHOW YOU" "THAT ELECTRICITY CAN ACTUALLY BE USEFUL," "SO WHEN MY YOUNG FRIEND HERE SAID SHE WANTED HER HAIR TEASED," "I THOUGHT MAYBE I WOULD DO IT ON THIS VAN DE GRAAFF MACHINE." "THIS WON'T HURT A BIT." "THERE WE GO." "WATCH WHAT HAPPENS WHEN I TURN IT ON." "YOU SEE THAT?" "ELECTRICITY CAN BE ABSOLUTELY HAIR-RAISING." "SHE WANTED TO KNOW HOW MUCH THIS WOULD COST." "I TOLD HER WHEN I WAS FINISHED, THERE'D BE NO CHARGE." "THIS IS A DIFFERENT KIND" "OF ELECTROSTATIC GENERATING MACHINE." "IT WORKS BY INDUCTION" "AND BY MAKING AND BREAKING CONTACTS." "BUT ITS BASIC PURPOSE" "ITS PURPOSE IS TO THROW SPARKS." "I THOUGHT THEY WERE GOING TO GIVE ME AN ELECTRIC MOTOR" "TO RUN THIS THING," "BUT WHEN I READ THE FINE PRINT IN MY CONTRACT," "IT SAID I HAD TO CRANK IT MYSELF." "THERE YOU GO." "IT'S A LIGHTNING MACHINE." "IT'S ACTUALLY QUITE DANGEROUS." "IF I GRABBED THE WRONG THING AT THE WRONG TIME," "YOU COULD LOSE A PROFESSOR OR, AT THE VERY LEAST," "LEARN A FEW WORDS THAT AREN'T IN THE CURRICULUM." "THE BIGGEST MACHINE OF THIS KIND EVER MADE" "WAS MADE BY A DUTCH PHYSICIST NAMED VAN MARUM." "LONG BEFORE THE WORK OF WIMSHURST AND VAN DE GRAAFF," "BACK IN THE 1780s AND 1790s, MARTINUS VAN MARUM, IN HOLLAND," "EXPERIMENTED WITH THE LARGEST ELECTROSTATIC GENERATING MACHINE" "EVER MADE." "IT HAD BEEN BUILT FOR VAN MARUM" "BY AN ENGLISH INSTRUMENT-MAKER NAMED JOHN CUTHBERTSON." "VAN MARUM'S GIANT MACHINE USED A BANK OF 100 LEIDEN JARS." "ITS ROTATING DISKS WERE OVER 6 FEET IN DIAMETER," "AND IT COULD HURL A LIGHTNING BOLT" "A DISTANCE OF MORE THAN 2 FEET." "IT WAS A KIND OF ELECTROSTATIC DINOSAUR," "THE END POINT OF EVOLUTION" "OF THE 18th-CENTURY ELECTROSTATIC GENERATING MACHINE," "AND IN A FEW YEARS, IT WAS EXTINCT" "BECAUSE IN ITALY, ALESSANDRO VOLTA" "HAD INVENTED A FAR MORE ELEGANT AND USEFUL DEVICE," "ONE THAT WOULD TAKE ELECTRICITY INTO A NEW ERA" "THE ELECTRIC BATTERY." "WE'LL GET TO THE ELECTRIC BATTERY SOON," "BUT FIRST I'LL TELL YOU ABOUT ANOTHER NEW IDEA" "THE ELECTRIC FIELD." "WE'LL DO THAT NEXT TIME." "CAPTIONING IS MADE POSSIBLE BY THE ANNENBERG/CPB PROJECT" "CAPTIONING PERFORMED BY THE NATIONAL CAPTIONING INSTITUTE, INC." "CAPTIONS COPYRIGHT 1987 CALIFORNIA INSTITUTE OF TECHNOLOGY," "THE CORPORATION FOR COMMUNITY COLLEGE TELEVISION, 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"