The Construction and Working of Kelvin's Thunderstorm

8/9/2019 The Construction and Working of Kelvin's Thunderstorm

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Kelvins

Thunderstorm

Construction and Working


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Abhishek Sharma

Certifcate

This is to certify that this project was

envisioned, researched, and completed byAbhishek Sharma, student of Class XII Shri

Sanatan haram Saraswati !al "andir #unjabi

!a$h, %ew elhi, under the $uidance of Mrs.

Seema Bhandari, epartment of #hysics, of

Shri Sanatan haram Saraswati !al "andir

#unjabi !a$h&

Signature

"rs& Seema !handari'#hysics Teacher(


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Acknowledgeme

ntsThis project may be titled as if it were made by a sin$le person,

but it wouldn)t have been possible without the help of many

more, without whose help this project simply couldn)t have

worked& I would like to thank those people for their patience and

e*ort in helpin$ us with this project&

+irstly, I would like to thank my #hysics teacher, Mrs. Seema

Bhandari, whose continued $uidance and help with the project

and the subject as a whole has been a hu$e help in all aspects of

completion of this project&

Secondly, I would like to thank another member of the school

physics department, Mr. Sanjeev , whose help still resonate with

us&

Thirdly, I would like to thank ProfessorWalter Lewin, "IT,whose lectures on electrostatics sparked our interest in the

elvin)s Thunderstorm e-periment&

And lastly, as always, I would like to thank all those anonymous

individuals on the internet whospent their time e-plainin$

physics to stran$ers who were thousands of kilometers

from them&

Index


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I& Certi.cateII& Acknowled$ements

III& /bjectiveI0& Introduction0& Construction0I& /bservations0II& #rinciple0III&1orkin$IX& #recautions and Sources of 2rror

X&


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Objective

To construct a workin$ elvin)s

Thunderstorm apparatus&

To understand the workin$ of elvin)s

Thunderstorm&

Introdution


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3ord elvin)s Thunderstorm is one of the most intri$uin$

demonstration of electrostatics at work& The device$enerates a potential di*erence as hi$h as 45,555 to

65,555 0olts, and does so without any battery or source

of electric current& The entire apparatus works on simple

electrostatic physics, yet its e-planation and its workin$

are very non7intuitive&

At .rst si$ht, the device seems like a ma$ical way to

create unlimited ener$y& 8owever, the laws of physics stillapply, and it is alas not a perpetual motion device&

8owever, the authors of this te-t .nd it interestin$

enou$h to devote countless hours into reproducin$ the

device and understandin$ its workin$s&

This project is the culmination of that work&

ConstructionThe device is simple to construct& +irst, we take a pair of

conductin$ buckets, A and !, and attach one conductin$ wire to

each& Then, we hold two conductin$ rin$s, A ) and !), each above

buckets A and ! respectively& The separation between the buckets

and the rin$s should be around 95 centimeters or $reater, for

reasons which will become clear soon& Then, we connect bucket A


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with metallic rin$ !)with the conductin$ wire already attached,

and connect bucket ! with rin$ A), as shown in the .$ure&


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%e-t, we attach a source of water supply 'any sli$htly conductive

li:uid will do, we chose water out of convenience( to a hori;ontal

pipe above the rin$s& At the ends of this pipe, we attach two

no;;les to ensure the water from each end


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4& The water initially falls to$ether in a coherent, almost

laminar


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lar$e potential di*erence causin$ a breakdown in the

.eld in a dielectric and causin$ a dischar$e&

! CO"#O$%A(

Coulomb)s law of electrostatic attraction is a key feature of this

e-periment& >iven by Coulomb in 4?@9, it was essential to the

development of electroma$netism&

It was .rst observed that matter possesses a property, by virtue

of which it attracted matter which had the opposite polarityB of

that object, and repelled thosewith the same polarityB of theproperty& This was called char$e&


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"athematically, it can be summari;ed as

F1=

q1

q2

4 0

r21

|r21|2

1here q1 is the electric char$e on object 4, q2 is the char$e on

object 6, 0 is the permittivity of free space, whose value is

0=8.8541878171012F/m


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r21 is the vector from object 6 to object 4, r21 is the unit vector

in the direction of r21 , and F1 is the force that acts on object 4

due to the presence of object 6&

)! *#*CT+O&TATIC

I,-"CTIO,

2lectrostatic induction is a redistribution of electrical char$e in an

object, caused by the inraa* $enerator use

this principle& ue to induction, the electrostatic potential


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'volta$e( is constant at any point throu$hout a conductor&

Induction is also responsible for the attraction of li$ht

nonconductive objects, such as balloons, paper or Styrofoam

scraps, to static electric char$es&

A normal unchar$ed piece of matter has e:ual numbers of

positive and ne$ative electric char$es in each part of it, located

close to$ether, so no part of it has a net electric char$e& The

positive char$es are the atomsE nuclei which are bound into the

structure of matter and are not free to move& The ne$ative

char$es are the atomsE electrons& In electrically conductive

objects such as metals, some of the electrons are able to move

freely about in the object&

1hen a char$ed object is brou$ht near an unchar$ed, electrically

conductin$ object, such as a piece of metal, the force of the

nearby char$e causes a separation of these internal char$es& +or

e-ample, if a positive char$e is brou$ht near the object 'see

picture at ri$ht(, the electrons in the metal will be attracted

toward it and move to the side of the object facin$ it& 1hen the

electrons move out of an area, they leave an unbalanced positive

char$e due to the nuclei& This results in a re$ion of ne$ative

char$e on the object nearest to the e-ternal char$e, and a re$ion

of positive char$e on the part away from it& These are called


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induced char$es& If the e-ternal char$e is ne$ative, the polarity of

the char$ed re$ions will be reversed&

Since this process is just a redistribution of the char$es that werealready in the object, it doesnEt chan$e the total char$e on the

objectF it still has no net char$e& This induction e*ect is reversibleF

if the nearby char$e is removed, the attraction between the

positive and ne$ative internal char$es cause them to intermin$le

a$ain&

.! *#*CT+IC

%+*AK-O(,

2lectrical breakdown or dielectric breakdown is a rapid reduction in

the resistance of an electrical insulator when the volta$e applied

across it e-ceeds the breakdown volta$e& This results in a portion of

the insulator becomin$ electrically conductive& 2lectrical breakdown

may be a momentary event 'as in an electrostatic dischar$e(, or

may lead to a continuous arc dischar$e if protective devices fail to

interrupt the current in a hi$h power circuit&


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1e will be dealin$ with electric breakdown of air& 2lectrical

breakdown occurs within a $as 'or mi-ture of $ases, such as air(

when the dielectric stren$th of the $as is e-ceeded& Ge$ions of hi$h

electrical stress can cause nearby $as to partially ioni;e and be$in

conductin$& #artial electrical breakdown of the air causes the HfreshairH smell of o;one durin$ thunderstorms or around hi$h7volta$e

e:uipment& Althou$h air is normally an e-cellent insulator, when

stressed by a suciently hi$h volta$e 'an electric .eld stren$th of

about = - 45D0Jm(, air can be$in to break down, becomin$ partially

conductive&

If the volta$e is suciently hi$h, complete electrical breakdown of

the air will culminate in an electrical spark or an electric arc thatbrid$es the entire $ap& 1hile the small sparks $enerated by static

electricity may barely be audible, lar$er sparks are often

accompanied by a loud snap or ban$& 3i$htnin$ is an e-ample of

an immense spark that can be many miles lon$& The color of the

spark depends upon the $ases that make up the $aseous media&

In our case, this spark is when the two conductive spheres reach

very hi$h potentials&


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(orkingAny small char$e on either of the two buckets suces to be$in

the char$in$ process& As most conductors are usually at least

sli$htly char$ed, this is never a problem& Suppose, therefore, that

the left bucket 'bucket !( has a small positive char$e& %ow the

ri$ht rin$ also has some positive char$e since it is connected to

the bucket& The char$e on the left rin$ will attract ne$ative

char$es in the water 'ions( into the ri$ht7hand stream by

electrostatic attraction& 1hen a drop breaks o* the end of theri$ht7hand stream, the drop carries ne$ative char$e with it& 1hen

the ne$atively char$ed water drop falls into its bucket 'the ri$ht

one(, it $ives that bucket and the attached rin$ 'the left one( a

ne$ative char$e&


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/nce the left rin$ has a ne$ative char$e, it attracts positive

char$e into the left7hand stream& 1hen drops break o* the end of

that stream, they carry positive char$e to the positively char$ed

bucket, makin$ that bucket even more positively char$ed&

So positive char$es are attracted to the left7hand stream by the

rin$, and positive char$e drips into the positively char$ed left

bucket& %e$ative char$es are attracted to the ri$ht7hand streamand ne$ative char$e drips into the ne$atively char$ed ri$ht

bucket& The positive feedback of this process makes each bucket

and rin$ increasin$ly char$ed& The hi$her the char$e, the more

e*ective this process of electrostatic induction is& urin$ the

induction process, there is an electrical current that


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form of positive or ne$ative ions in the water of the supply lines&

This is separate from the bulk


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The char$e separation and build7up of electrical ener$y ultimately

comes from the $ravitational potential ener$y released when thewater falls& The char$ed fallin$ water does electrical work a$ainst

the like7char$ed containers, convertin$ $ravitational potential

ener$y into electrical potential ener$y, plus motional kinetic

ener$y& The kinetic ener$y is wasted as heat when the water

drops land in the buckets, so when considered as an electric

power $enerator the elvin machine is very inecient& 8owever,

the principle of operation is the same as with other forms of

hydroelectric power& As always, ener$y is conserved&


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Precautions /

&ources o0 *rror

! P+*CA"TIO,&

4& The metal spheres should be as close as possible to each

other without actually touchin$&

6& The rin$s should be wide enou$h so that no droplets can

touch them, even at ma-imum dispersion&

=& The separation between the rin$s and the buckets shouldn)t

be so hi$h that the droplets can $o out and spill outside the

bucket&

L& The conductin$ wires between the rin$s and the buckets

shouldn)t overlap or cross each other& They should be

insulated&


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)! &O"+C*&O1*++O+

4& The metal spheres can be too far apart for the air to reach

the breakdown point&

6& The metal spheres could be touchin$& In this case, there

can)t be any spark as the current can easily


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#hysics, for Class XII, %C2GT

+undamentals of #hysics, 8alliday, Gesnick and 1alker

"IT @&56 lectures, #rofessor 1alter 3ewin, "IT

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The Construction and Working of Kelvin's Thunderstorm

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