Exploring Electrical Exploring Electrical TechnologyTechnology

Reaction to Ben Franklin’s Reaction to Ben Franklin’s Electricity & Lightning RodElectricity & Lightning Rod

Drama in the French Drama in the French AcademyAcademy

• Abbe NolletAbbe Nollet– MemberMember– Respected lecturerRespected lecturer– Authority on electricity with a 2-fluid Authority on electricity with a 2-fluid

theorytheory•Promoted it widelyPromoted it widely

•Used it to explain the Leiden JarUsed it to explain the Leiden Jar

Drama in the French Drama in the French AcademyAcademy• Comte de BuffonComte de Buffon

– Rival and superior to NolletRival and superior to Nollet– Previously snubbed by NolletPreviously snubbed by Nollet– Seeking revenge, he found Franklin’s bookSeeking revenge, he found Franklin’s book– Had Franklin’s book translated into FrenchHad Franklin’s book translated into French

•Translation done by DalibardTranslation done by Dalibard

•Put forth Franklin’s book to challenge NolletPut forth Franklin’s book to challenge Nollet

Nollet’s 2-fluid vs. Franklin’s 1-fluid theoryNollet’s 2-fluid vs. Franklin’s 1-fluid theory

Drama in the French Drama in the French AcademyAcademy• DalibardDalibard

– In 1752 he upstaged Nollet before the kingIn 1752 he upstaged Nollet before the king•Showed the king some of Franklin’s Showed the king some of Franklin’s

experimentsexperiments•Later that year followed an experiment Later that year followed an experiment

suggestedsuggested by Franklin to become the 1 by Franklin to become the 1stst to to draw electricity from a thunderstormdraw electricity from a thunderstorm

– An account of his experience with lightningAn account of his experience with lightning•Shared at the academyShared at the academy•Began the pursuit of drawing “fire” from clouds Began the pursuit of drawing “fire” from clouds

(a.k.a. thunderbolt collecting)(a.k.a. thunderbolt collecting)

Drama in the French Drama in the French AcademyAcademy

• Franklin’s book & experimentsFranklin’s book & experiments– Challenged NolletChallenged Nollet– Fueled debate and discussion: served to Fueled debate and discussion: served to

further promote Franklin’s notorietyfurther promote Franklin’s notoriety

Franklin’s SideFranklin’s Side

• Proposed drawing lightning from the skyProposed drawing lightning from the sky– Before his book was published in 1751Before his book was published in 1751– Such an exp’t not actually tried until 1752Such an exp’t not actually tried until 1752

• Had not yet done it himselfHad not yet done it himself• Franklin’s kite experimentFranklin’s kite experiment

– Devised and carried out before news of the Devised and carried out before news of the experiment in France reached himexperiment in France reached him

– Importance of the pointed collecting rod Importance of the pointed collecting rod being grounded: stated but not always being grounded: stated but not always observedobserved

Lightning CollectingLightning Collecting

• Popular: a “sport” in the interest of sciencePopular: a “sport” in the interest of science• CasualitesCasualites

– occurred due to lack of safety precautionsoccurred due to lack of safety precautions– George Wilhelm RichmannGeorge Wilhelm Richmann

• Most famous example Most famous example • Conducted his lightning rod exp’t at the Academy in St. Conducted his lightning rod exp’t at the Academy in St.

Petersburg RussiaPetersburg Russia• Inadequate grounding killed him in his attemptInadequate grounding killed him in his attempt

– Evident danger restrained othersEvident danger restrained others– Provided negative press for Nollet against FranklinProvided negative press for Nollet against Franklin

• That Franklin escaped such dangers: a That Franklin escaped such dangers: a miracle?miracle?

Impact: Franklin’s Lightning Impact: Franklin’s Lightning RodRod• Practical applications: by 1752, major Practical applications: by 1752, major

buildings in Philly had lightning buildings in Philly had lightning rodsrods

• Guarded acceptance: lightning rods Guarded acceptance: lightning rods were were not without controversynot without controversy

• Superstitions revealed: throughout Superstitions revealed: throughout Europe Europe at the time, during at the time, during thunderstorms, thunderstorms, churches rang bells churches rang bells to ward off to ward off lightning bolts !lightning bolts !

To Use the Rod or Not?To Use the Rod or Not?

• Superstitious viewSuperstitious view– Lightning as tool of evil forces: Lightning as tool of evil forces:

repelled by ringing the bellsrepelled by ringing the bells– Result: Bell ringers reported to have been Result: Bell ringers reported to have been

killed by killed by thunderbolts (as electricity passed thunderbolts (as electricity passed from the from the bell down the cord)bell down the cord)

• Effectiveness of the RodEffectiveness of the Rod– Widely accepted: by academics and Widely accepted: by academics and

researchers from 1752 onresearchers from 1752 on– Resisted: by common people who viewed it as Resisted: by common people who viewed it as

an attempt to alter or replace the ways of God an attempt to alter or replace the ways of God with sciencewith science

Franklin Fails to Convince Franklin Fails to Convince Most Church LeadersMost Church Leaders

• Franklin: unsurprised by resistance Franklin: unsurprised by resistance commented that 1000 years of experience commented that 1000 years of experience speaks otherwise to the effectiveness of bell-speaks otherwise to the effectiveness of bell-ringing to dissipate lightning and suggested ringing to dissipate lightning and suggested that maybe a new “trick” was in orderthat maybe a new “trick” was in order

• Church leaders: also generally opposed to Church leaders: also generally opposed to lightning rods, with a few rare exceptionslightning rods, with a few rare exceptions

• Conclusion: ignorance & superstition played Conclusion: ignorance & superstition played a large role in the slow acceptance of a large role in the slow acceptance of lightning rods, especially in Europelightning rods, especially in Europe

Nollet Opposes RodNollet Opposes Rod

• Motivation: his still wounded pride at being Motivation: his still wounded pride at being upstaged by many of Franklin’s discoveriesupstaged by many of Franklin’s discoveries

• Authority: continued to be well-known and Authority: continued to be well-known and respected respected

• Approach: highlighted tragedies like Approach: highlighted tragedies like Richmann and other isolated cases where Richmann and other isolated cases where buildings had been destroyed due to buildings had been destroyed due to inadequate grounding to blame and inadequate grounding to blame and discredit Franklin’s Rod discredit Franklin’s Rod

Should Rods be Pointed or Should Rods be Pointed or Blunt? Blunt? • WilsonWilson

– Member of the RSLMember of the RSL– Argued for bluntArgued for blunt

• Franklin: argued for pointsFranklin: argued for points

• Issue became politicalIssue became political– Pointed rods blamed for minor damage to British Pointed rods blamed for minor damage to British

powder magazines in late 1770spowder magazines in late 1770s– Wilson, funded by George III, made blunt rods Wilson, funded by George III, made blunt rods

British practice vs. American colonies & British practice vs. American colonies & Franklin’s points Franklin’s points

What do the Van De Graff and video demonstrations reveal on this issue?

Summary on Franklin’s Summary on Franklin’s ReputationReputation

• 1 of most noted & respected scientists 1 of most noted & respected scientists in his day, despite only 9 years of exp’tsin his day, despite only 9 years of exp’ts

• Much more respected overseas sinceMuch more respected overseas since– Greater spirit of science & invention existed Greater spirit of science & invention existed

in Europe than as yet in the coloniesin Europe than as yet in the colonies– Academics undeveloped in colonies during Academics undeveloped in colonies during

his lifetime (Franklin started 1his lifetime (Franklin started 1stst learned learned society)society)

Summary on Franklin’s Summary on Franklin’s TheoryTheory• Held a 1-fluid theory that challenged Held a 1-fluid theory that challenged

Nollet’s prevailing 2-fluid theory Nollet’s prevailing 2-fluid theory

• Called an object with excess fluid Called an object with excess fluid “electrised positive” and one with a lack of “electrised positive” and one with a lack of such fluid “electrised negative”such fluid “electrised negative”

• Thought the fluid attracted ordinary Thought the fluid attracted ordinary matter but repelled itself, but failed to matter but repelled itself, but failed to explain repulsive forces between two explain repulsive forces between two negatively charged objectsnegatively charged objects

Franklin’s ContributionsFranklin’s Contributions

• One-Fluid Theory of ElectricityOne-Fluid Theory of Electricity

• Terms Positive (+) & Negative (-)Terms Positive (+) & Negative (-)

• Demonstrated electricity in Nature Demonstrated electricity in Nature (lightning electricity same as gen. in lab)(lightning electricity same as gen. in lab)

• Principle of Conservation of ChargePrinciple of Conservation of Charge

• Electrostatic induction & conductionElectrostatic induction & conduction

• Recommended practice of groundingRecommended practice of grounding

• Invented the Lightning RodInvented the Lightning Rod

Significance of Lightning Rod Significance of Lightning Rod (Beyond its Practical Value)(Beyond its Practical Value)

• Electrical phenomena occur in natureElectrical phenomena occur in nature– On quite a large scaleOn quite a large scale– An actual force of natureAn actual force of nature

• Confirmed Bacon’s predictionConfirmed Bacon’s prediction– 11stst significant example significant example– Scientific discoveries in natural world lead to Scientific discoveries in natural world lead to

major practical inventionsmajor practical inventions

• Promoted value of lightning experiments Promoted value of lightning experiments in the war against superstitionin the war against superstition

Contemporaries of FranklinContemporaries of Franklin

• Beccaria: an Italian chair of physics Beccaria: an Italian chair of physics at the University of Turin (1748)at the University of Turin (1748)– Expt’d with lightning rod & Expt’d with lightning rod &

thoroughly examined the phenomenonthoroughly examined the phenomenon– Published a treatise supporting Published a treatise supporting

Franklin’s discoveries entitled Franklin’s discoveries entitled Del Del l’eletticismo Artificiale e naturale l’eletticismo Artificiale e naturale in in 17531753

Contemporaries of FranklinContemporaries of Franklin

• Aepinus: an applied mathematician, Aepinus: an applied mathematician, astronomer at Berlin Academy in Germany astronomer at Berlin Academy in Germany (1755)(1755)– Studied Franklin’s work & translated it into GermanStudied Franklin’s work & translated it into German– Extended Franklin’s 1-fluid theory to explain why 2 Extended Franklin’s 1-fluid theory to explain why 2

negative forces repelnegative forces repel– Quantified Franklin’s observations with surprising Quantified Franklin’s observations with surprising

accuracyaccuracy– In 1759 published a reformulation of FranklinIn 1759 published a reformulation of Franklin

• Overlooked by his contemporariesOverlooked by his contemporaries

• Inaccessible and unreadable due to its math & LatinInaccessible and unreadable due to its math & Latin

Contemporaries of FranklinContemporaries of Franklin

• Priestly: an English clergyman, political Priestly: an English clergyman, political theorist and physical scientisttheorist and physical scientist– Met Franklin in LondonMet Franklin in London– Elected member of RSL in 1766 based on his Elected member of RSL in 1766 based on his

electrical experimentselectrical experiments– Encouraged by Franklin to summarize work Encouraged by Franklin to summarize work

• on knowledge of electricity to date on knowledge of electricity to date • In 1767 pub. In 1767 pub. The History and Present State of The History and Present State of

ElectricityElectricity

– Predicted Predicted inverse square lawinverse square law of electrical of electrical attraction based on his own observationsattraction based on his own observations

– Interest turned toward chemistry as he saw Interest turned toward chemistry as he saw chemical changes brought about by electricitychemical changes brought about by electricity

Contemporaries of FranklinContemporaries of Franklin

• Cavendish: a wealthy, unsociable, Cavendish: a wealthy, unsociable, Cambridge educated physicistCambridge educated physicist– Deepened and extended Aepinus work in his Deepened and extended Aepinus work in his

classic paper of 1771classic paper of 1771– Exemplified how far one could go in physics with Exemplified how far one could go in physics with

concepts, mathematics and apparatusconcepts, mathematics and apparatus– Clever experiments led him also to deduce that Clever experiments led him also to deduce that

the law governing electrical forces depended on the law governing electrical forces depended on the the inverse square of distanceinverse square of distance btwn btwn electrified objectselectrified objects

– Saw no need to publish, so received no creditSaw no need to publish, so received no credit

Contemporaries of FranklinContemporaries of Franklin

• Coulomb: a French physicist, experienced Coulomb: a French physicist, experienced military engineermilitary engineer– Assisted in becoming a member of Paris Assisted in becoming a member of Paris

Academy by winning a prize competition Academy by winning a prize competition • Involved the variation of Earth’s magnetism typically Involved the variation of Earth’s magnetism typically

measured by a needle on a pivoted pointmeasured by a needle on a pivoted point

• Based on his knowledge of ropes, he perceived Based on his knowledge of ropes, he perceived performance would be improved by suspending the performance would be improved by suspending the needle from a silk thread allowing it to oscillate freely needle from a silk thread allowing it to oscillate freely in a horizontal plane in a horizontal plane

• Concluded that restoring force torsion was proportional Concluded that restoring force torsion was proportional to the angle of twistto the angle of twist

Coulomb Discovers and Gets Coulomb Discovers and Gets Credit for Inverse Square Law Credit for Inverse Square Law (ISL)(ISL)• After perfecting prize winning technique After perfecting prize winning technique

with small mechanical forceswith small mechanical forces– Went on to electricityWent on to electricity– Precisely measured electrical force between Precisely measured electrical force between

objects as it depended on distance and objects as it depended on distance and amounts of charge to establish ISLamounts of charge to establish ISL

– Published his findings in 1785-89Published his findings in 1785-89•Not Not immediatelyimmediately accepted outside France accepted outside France•But by 1800, few questioned it anywhere But by 1800, few questioned it anywhere

See also Coulomb’s ingenious torsion balance pictured in Electricita.

Instrumentation Instrumentation During the 4During the 4thth Period (1760-90) Period (1760-90)

• Devices invented and developed to both Devices invented and developed to both generate large amounts of charge as well as generate large amounts of charge as well as measure small amounts of it sensitivelymeasure small amounts of it sensitively– Electrometer (1766 by de Soussure)Electrometer (1766 by de Soussure)

• Measured electric potential by means of attraction or Measured electric potential by means of attraction or repulsion of charged objectsrepulsion of charged objects

• A version was incorporated into Coulomb’s balanceA version was incorporated into Coulomb’s balance

– Electrostatic machine (1768 by Ramsden)Electrostatic machine (1768 by Ramsden)• Used glass plates to generate chargeUsed glass plates to generate charge

– Electroscope (gold leaf version in 1786 by Bennet)Electroscope (gold leaf version in 1786 by Bennet)• Perhaps most sensitive way of meas. elect. charge of its Perhaps most sensitive way of meas. elect. charge of its

time time

Era of Early Electrical Science Era of Early Electrical Science Ends;Ends;Launches A New Age of Launches A New Age of ElectricityElectricity• Instrumentation sets the stage at the end Instrumentation sets the stage at the end

of the 18of the 18thth century for the turn of the 19 century for the turn of the 19thth

• Enter two ItaliansEnter two Italians– Luigi GalvaniLuigi Galvani– Allessandro VoltaAllessandro Volta

• Their contribution launched electricity Their contribution launched electricity into the age of truly life changing into the age of truly life changing applicationsapplications