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PHYSICSPART I

TEXTBOOKFOR CLASS XII

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PHYSICSPART I

TEXTBOOKFOR CLASS XII

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Firs t Edi t ion

December 2006 Pausa 1 928

Repr in tedDecember 2007 Agrahay ana 1929


PD 360T RNB

Nat ional Counci l o f Educat ional

R es ea r ch a n d T r a i n i n g , 2 0 0 6

Rs . 11 5 .00

Printed on 8 0 GS M pape r w ith NCERT

w atermark

Publ ished a t the Pu bl icat ion Depar tmen tby the Secretary, National Council of

Edu cat iona l Research a nd Training,

Sri Au robindo Marg, New Delh i 110 0 16

an d pr inted at Prabh at Pr int ing Press ,

D-23, Indu strial Area S ite-A, Mathu ra

ISBN 81-7450-631-4

ALL RIGHTS RESERVED

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sold, hired out or otherwise disposed of without the publishers consent, in any formof binding or cover other than that in which it is published.

The correct price of this publication is the price printed on this page, Any revised

price indicated by a rubber stamp or by a sticker or by any other means is incorrectand should be unacceptable.

OFFICES OF THE PUBLICATIONDEPARTMENT, NCERT

NCERT CampusSri Aurobindo Marg

New Delhi 110 016 Phone : 011-26562708

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Publicatio n Team

H ea d , Pu b lic a tio n : Peyy eti Rajak uma rDepar tment

Ch ief Pr od u ct ion : Shiv Kuma r

Officer

Ch ief Ed itor : Shveta Uppal

Ch ief Bu s in es s : Gautam GangulyManager

As sis ta n t E ditor : R.N. Bh ardw aj

Produ ct ion Ass is tant : Praka sh Veer Singh

Cover, Lay out and I llus t ra t ions

Shw eta Rao

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FOREWORD

Th e Nationa l Cur riculum Fram ework (NCF), 2005 recomm end s th at ch ildren s l ife at sch ool mu st

be lin ked to th eir life outs ide the sch ool. Th is principle m ark s a d epar tu re from t he legacy of bookishlearning which cont inues to shape our sys tem and causes a gap be tween the school , home and

comm u nity. The s yllabi and textbooks developed on th e bas is of NCF signify an a ttem pt to implemen tthis bas ic idea . They a lso a t tempt to d iscourage rote learning and the maintenance of sharp

boundaries between different subject areas. We hope these measures will take us s ignificantlyfu rth er in th e direction of a ch ild-centr ed system of edu cation ou tlined in th e Nationa l Policy on

Edu cation (NPE), 19 86 .

The s u ccess of this effort depend s on the s teps th at s chool principals an d teach ers will take to

encour age children to reflect on th eir own learning an d to pu rsu e ima gina tive activities an d qu estions .We m u st recognise th at, given s pace, time an d freedom, ch ildren genera te n ew knowledge by engaging

with the inform ation pas sed on to them by adu lts . Treating the prescribed textbook as the s ole basisof examination is one of the key reasons why other resources and sites of learning are ignored.

Inculcating creativity and initiative is possible if we perceive and treat children as participants inlear n ing, not as receivers of a fixed b ody of kn owledge.

These aim s imp ly cons iderable cha nge in s chool routines an d m ode of fu n ctionin g. Flexibility inthe daily t ime-table is as necessary as rigour in implementing the annual calendar so that the

required nu mb er of teaching days a re actu ally devoted to teaching. The m ethods u sed for teach ingan d evalua tion will also determ ine h ow effective this t extbook pr oves for m ak ing childrens life at

school a h app y experience, rath er tha n a sou rce of s tress or boredom. Syllabu s designers ha ve triedto addr ess th e problem of curr icular b u rden by restru ctur ing an d reorienting kn owledge at different

sta ges with greater con siderat ion for child ps ychology an d th e time availab le for teach ing. The textb ookattempts to enhance th is endeavour by giving higher pr ior i ty and space to opportuni t ies for

contempla t ion and wondering, d iscuss ion in smal l groups , and ac t iv i t ies requir ing hands-onexperience.

The National Council of Educational Research and Training (NCERT) appreciates the hardwork done by th e textbook developm ent com m ittee resp onsible for this book. We wish to tha nk th e

Cha irperson of th e ad visory group in science an d m ath ema tics , Pr ofessor J .V. Narlikar a nd th eCh ief Advisor for th is book, Pr ofess or A.W. J osh i for gu iding th e work of this com m ittee. Several

teachers contributed to the development of this textbook; we are grateful to their principals for

ma king this possible. We are ind ebted to the insti tu tion s an d organisat ions which ha ve generou slyperm itted u s to dra w up on th eir resou r ces, mater ial an d pers onn el. We are esp ecially grat efu l tothe members of the National Monitoring Committee, appointed by the Department of Secondary

an d Higher E du cat ion, Minis t ry of Hum an Resource Development u nd er the Ch airpersonsh ip ofProfessor Mrinal Miri an d Professor G.P. Desh pa nd e, for th eir valua ble t ime a nd contribu tion . As

an organ isa t ion comm it ted to sys temic reform a nd cont inu ous imp rovement in the qu al ity of it sprodu cts , NCERT welcomes commen ts a nd su gges t ions wh ich wi ll ena ble us t o un dertake fur th er

revision an d refinemen t.

Director

New Delh i Na t ion a l Cou n cil of E du ca t ion a l

20 December 200 6 Research a nd Tra ining

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TEXTBOOK DEVELOPMENT COMMITTEE

CHAIRPERSON, ADVISORY GROUPFOR TEXTBOOKSIN SCIENCEAND MATHEMATICS

J .V. Nar lika r, Em eritu s Profes s or, Int er -Un ivers ity Centre for Ast ron omy a n d Astroph ysics

(IUCAA), Gan esh khin d, Pun e Un iversity Cam pu s, Pu n e

CHIEF ADVISORA.W. J osh i, Honora ry Visiting Scient ist, Nat ion al Cen tre for Rad io Ast roph ysics (NCRA), Pu n e

University Cam pu s, Pu ne (Formerly Professorat Departm ent of Physics, University of Pun e)

MEMBERS

A.K. Ghatak, Emeritus Professor,Department of Physics, Indian Institute of Technology,

New Delh i

Alika Khare, Professor, Departm ent of Physics, In dian Ins titut e of Techn ology, Guwah ati

An jali Ksh irsa gar, Reader, Departm ent of Physics, University of Pun e, Pun e

Anu radha Mathu r , PGT, Moder n S ch ool, Vas an t Vih ar, New Delh i

Atu l Mody, Lecturer (S.G.), VES College of Arts , Science an d Comm erce, Mu m ba iB.K. Sha rm a, Professor, DES M, NCER T, New Delh i

Chitra Goel, PGT, Rajkiya Pratibh a Vikas Vidyalaya, Tyagra j Nagar , New Delhi

Gagan Gupta , Reader, DES M, NCER T, New Delh i

H.C. Pradh an , Professor, Homi Bhab ha Centr e of Science Ed u cation (TIFR ), Mum ba i

N. Panchapak esan , Professor(Retd. ), Depart men t of Physics an d Astr ophysics, University of

Delhi, Delh i

R. J osh i, Lecturer(S.G .), DESM, NCERT, New Delh i

S.K. Dash , Rea der, DES M, NCERT, New Delhi

S. Rai Chou dh ary,Professor,

Depart men t of Physics an d Astr oph ysics, University of Delh i, DelhiS.K. Upad h yay, PGT, J awa h ar Navoda ya Vidyalaya, Muza ffar Naga r

S.N. Prabh aka ra , PGT, DM School, Region al Ins titu te of Edu cat ion (NCERT), Mysore

V.H. Rayba gkar, Reader, Nowrosjee Wadia College, Pu n e

Vishwajeet Kulkarni, Teacher(Grad e I), Higher Secon da ry Section, Sm t. Parvatiba i Ch owgu le

College, Marga o, Goa

MEMBER-COORDINATOR

V.P. Srivas ta va, Reader, DES M, NCER T, New Delh i

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CONSTITUTION OF INDIA

Fundamental Duties

Fundamental Duties It shall be the duty of every citizen of India

(a) to abide by the Constitution and respect its ideals and institutions, the National

Flag and the National Anthem;

(b) to cherish and follow the noble ideals which inspired our national struggle for

freedom;

(c) to uphold and protect the sovereignty, unity and integrity of India;

(d) to defend the country and render national service when called upon to do so;

(e) to promote harmony and the spirit of common brotherhood amongst all the peopleof India transcending religious, linguistic and regional or sectional diversities; to

renounce practices derogatory to the dignity of women;

(f) to value and preserve the rich heritage of our composite culture;

(g) to protect and improve the natural environment including forests, lakes, rivers,

wildlife and to have compassion for living creatures;

(h) to develop the scientific temper, humanism and the spirit of inquiry and reform;

(i) to safeguard public property and to abjure violence;

(j) to strive towards excellence in all spheres of individual and collective activity so

that the nation constantly rises to higher levels of endeavour and achievement;

(k) who is a parent or guardian, to provide opportunities for education to his child or,

as the case may be, ward between the age of six and fourteen years.

Part IV A (Artic le 5 1 A)

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ACKNOWLEDGEMENTS

The National Council of Educational Research and Training acknowledges the valuable

contr ibu tion of th e in dividu als an d organ isations involved in th e developm ent of Physics Textbookfor Class XII. Th e Coun cil also a ckn owledges th e valua ble contr ibu tion of th e followin g acad emics

for reviewing a nd refining the m an u scripts of th is book:

Anu Venu gopalan , Lecturer, Sch ool of Bas ic an d App lied Sciences, GGSIP Un iversity, Delhi;A.K. Das, PGT, St. Xaviers Senior Secondary School, Delhi; Bharati Kukkal, PGT, Kendriya

Vidyalaya, Pushp Vihar, New Delhi; D.A. Desai, Lecturer(Retd.), Ruparel College, Mumbai;Devendr a Kum ar, PGT, Rajkiya Pra tibh a Vikas Vidyalaya , Yam u n a Vih ar, Delhi; I.K. Gogia, PGT,

Kend riya Vidyalaya, Gole Market , New Delhi; K.C. Sh ar ma , Reader, Region al Institu te of Edu cation

(NCERT), Ajmer; M.K. Nandy, Associate Professor, Departm ent of Physics, In dian Ins titut e ofTechn ology, Gu wah ati; M.N. Bap at, Reader, Regiona l In st itu te of Edu cat ion (NCERT), Mysore;

R. Bha ttach arjee, Ass tt. Profess or, Departm ent of Electronics a nd Comm u nication En gineering,Ind ian In stitu te of Techn ology, Guwah ati; R.S. Das , Vice-Principa l (Retd .), Balwan t Ray Meht a

Sen ior Second ary Sch ool, Lajpat Nagar, New Delh i; San geeta D. Gadr e, Reader, Kiror i Mal College,

Delhi; Suresh Ku ma r, PGT, Delh i Pu blic Sch ool, Dwarka , New Delh i; Su sh m a J aireth , Reader,Depa rtm en t of Women s Stu dies, NCER T, New Delhi; Sh yam a Rath , Reader, Departm ent of Physics

an d Ast roph ysics, University of Delh i, Delh i; Yas h u Ku ma r, PGT, Ku lachi Han s Ra j Model School,As h ok Viha r, Delhi.

Th e Coun cil also gratefu lly ackn owledges th e valu ab le contr ibut ion of th e followin g acad emics

for th e editin g an d fin alisa tion of th is book: B.B. Tripa th i,Profes sor (Retd .), Departm ent of Physics,In dian In st itu te of Tech n ology, New Delhi; Dipan K. Ghos h , Professor, Departm ent of Physics,

Ind ian Ins titut e of Techn ology, Mu mb ai; Dipan jan Mitra , Scientist, Nat ional Cent re for RadioAstrophysics (TIFR), Pune; G.K. Mehta, Raja Ramanna Fellow , Inter -University Accelerator

Cent re, New Delh i; G.S. Visweswa ra n , Professor, Depart men t of Electrical En gineering, In dian

Ins titu te of Techn ology, New Delh i; H.C. Kan dp al, Head, Optical Radiation Stan dard s, NationalPhys ical Lab orat ory, New Delh i; H.S. Man i, Raja Ramanna Fellow , Institute of Mathematical

Sciences, Chennai; K. Thyagarajan, Professor, Depar tment of Physics, Indian Inst i tute ofTechnology, New Delhi; P.C. Vinod Kumar, Professor, Department of Physics, Sardar Patel

Univers ity, Vallabh Vidyan agar, Gujar at ; S. An n ap oorn i, Professor, Depa rtm ent of Physics an dAstrophysics, University of Delhi, Delhi; S.C. Dutta Roy, Eme ritus Profes s or, Depar tment ofElectrical En gin eering, Ind ian In st itu te of Techn ology, New Delh i; S.D. J ogleka r, Professor,

Departm ent of Physics, Indian Ins titute of Techn ology, Kan pu r; V. Su nd ara Raja, Professor, SriVenkateswara University, Tirupati.

Special tha nk s are du e to Huku m Singh, Profess or an d Head ,DESM, NCERT for h is su pp ort.

Th e Coun cil also ackn owledges th e su pport provided by th e APC office an d t he adm inistrativest aff of th e DESM; Deepa k Kapoor, Incharge, Comp u ter Sta t ion; Ind er Ku ma r, DTP Operator;

Mohd. Qam ar Tabrez, Copy Ed itor; Ash ima Srivas tava, Proof Rea d erin sh aping this book.The contributions of the Publication Department in bringing out this book are also duly

acknowledged.

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CONSTITUTION OF INDIAPart III (Articles 12 35)

(Subject to certain conditions, some exceptionsand reasonable restrictions)

guarantees these

Fundamental Rights

Right to Equality

before law and equal protection of laws;

irrespective of religion, race, caste, sex or place of birth;

of opportunity in public employment;

by abolition of untouchability and titles.

Right to Freedom

of expression, assembly, association, movement, residence and profession;

of certain protections in respect of conviction for offences;

of protection of life and personal liberty;

of free and compulsory education for children between the age of six and fourteen years;

of protection against arrest and detention in certain cases.

Right against Exploitation

for prohibition of traffic in human beings and forced labour;

for prohibition of employment of children in hazardous jobs.

Right to Freedom of Religion

freedom of conscience and free profession, practice and propagation of religion;

freedom to manage religious affairs;

freedom as to payment of taxes for promotion of any particular religion;

freedom as to attendance at religious instruction or religious worship in educational

institutions wholly maintained by the State.

Cultural and Educational Rights

for protection of interests of minorities to conserve their language, script and culture;

for minorities to establish and administer educational institutions of their choice.

Right to Constitutional Remedies

by issuance of directions or orders or writs by the Supreme Court and High

Courts for enforcement of these Fundamental Rights.

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PREFACE

It gives me pleasu re to place this book in th e han ds of the s tu dents , teachers an d th e pu blic a t

large (whose r ole can not be overlooked). It is a n atu ral s equel to th e Clas s XI textbook wh ich

was br ough t ou t in 200 6. Th is b ook is a lso a tr immed version of th e textbooks which existed s o

far. The ch apter on th ermal an d ch emical effects of curr ent h as been cu t ou t. This topic has also

been dropped from th e CBSE syllabus . Similar ly, the ch apter on commu nications ha s beensu bs tan tially cu rtailed. It ha s been rewritten in an easily compreh ens ible form.

Althou gh most oth er chapt ers h ave been ba sed on th e ear lier versions , several par ts an d

sections in th em h ave been r ewritten . Th e Developmen t Team h as been gu ided by the feedback

received from inn u mera ble teach ers across th e coun try.

In p rodu cin g these b ooks, Clas s XI as well as Clas s XII, there h as been a ba sic chan ge ofemph asis. Both the books present ph ysics to stu dents withou t assu ming that they wou ld pu rsu e

this s u bject beyond the h igher secondar y level. This n ew view has been p rompted b y the various

observations and suggest ions made in the National Curr iculum Framework (NCF), 2005.

Similarly, in todays edu cationa l scen ario wh ere stu den ts can opt for various combin ations of

su bjects , we cann ot assu me th at a ph ysics s tu dent is a lso stud ying ma them atics. Therefore ,ph ysics h as to be presented, so to say, in a s tan d-alone form.

As in Class XI textbook, som e interest ing box items ha ve been ins er ted in m an y chapters .Th ey are n ot mean t for teaching or exam inations . Th eir pu rpose is to catch th e atten tion of th e

read er, to sh ow some a pp lications in da ily life or in oth er ar eas of science an d t echn ology, to

su ggest a s imple experiment, to sh ow conn ection of concepts in d ifferent a reas of ph ysics, an din genera l, to break th e monotony an d enliven th e book.

Featu res like Su mm ary, Points t o Pond er, Exercises a n d Additional Exercises a t th e end of

each chap ter, an d Exam ples h ave been re ta ined. Several concept-bas ed Exercises h ave beentra n sferred from en d-of-cha pter Exercises to Exam ples with Solu tions in th e text. It is hoped

tha t th is will make th e concepts discus sed in th e chapt er more comp rehen sible . Several newexam ples an d exercises h ave been ad ded. Stud ents wishing to pu rsu e physics fu r th er would

find Poin ts t o Pon der a n d Add itiona l Exercises very u seful an d th ou ghtful. To provide resources

bey ond the textbookan d to encoura ge eLearning, each cha pter ha s been p rovided with some

relevan t website addres ses u nd er the title ePhysics. These s ites provide a dditiona l ma terials onspecific topics and also provide learners the opportunites for interactive demonstrations/

experiments.The intr icate concepts of physics must be understood, comprehended and apprecia ted.

Students must learn to ask questions like why, how, how do we know it. They will findalmost a lways th at th e quest ion why h as n o ans wer within th e domain of ph ysics an d science

in general . But tha t i tse lf is a learning exper ience, is i t n ot? On th e other h an d, th e quest ionh ow ha s been reason ably well ans wered by ph ysicists in th e case of most n atu ral phen omena .

In fact, with th e un dersta nd ing of how things ha ppen , it ha s been poss ible to ma ke u se of ma n yph enomena to create techn ological applicat ions for the u se of hu ma ns .

For examp le, cons ider sta temen ts in a book, like A n egatively cha rged electron is a ttra ctedby th e pos itively cha rged p late, or In th is experim en t, ligh t (or electron ) beh aves like a wave.

You will realise t h at it is n ot poss ible to an swer why. Th is qu estion b elongs to th e dom ain ofph ilosoph y or meta ph ysics. Bu t we can an swer h ow, we can find t h e force acting, we can find

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th e wavelength of th e ph oton (or electron), we can determine h ow things b eha ve u n der different

conditions, an d we can d evelop ins tru men ts which will u se th ese phen omena to ou r advan tage.

It h as been a pleasu re to work for th ese books a t th e high er second ary level, alon g with a

team of m emb ers. The Textbook Developm ent Team , th e Review Team an d Ed itin g Team s involvedcollege and u n iversity teachers , teach ers from In dian Ins titut es of Techn ology, scient ists from

na tional inst i tutes an d laborator ies , as well as h igher secondary teachers. The feedback an d

critical look provided by h igh er seconda ry teachers in t h e variou s team s ar e highly lau da ble.

Most box items were generated by memb ers of one or the oth er team, b u t th ree of them were

generat ed by friends an d well-wish ers n ot pa rt of an y team . We ar e th an kful to Dr P.N. Sen ofPu n e, Profess or Roopm an jari Ghos h of Delh i an d Dr Rajesh B Kh ap ar de of Mu mb ai for allowin g

us to use their box items, respectively in Chapters 3, 4 (Part I) and 9 (Part II) . We are very

th an kfu l to the m embers of the Review and Edit ing Worksh ops to d iscu ss an d refine the firs t

dra ft of the textb ook. We also express ou r gratitu de to Prof. Krishn a Kum ar, Director, NCERT,for entru st ing u s with the tas k of presen ting th is textbook as a p ar t of the na tiona l effor t forimprovin g science edu cation. I also th an k Prof. G. Ravin dra , J oint Director, NCERT, for h is h elp

from t ime-to- t ime. Prof . Hukum Singh, Head, Depar tment of Education in Science and

Mathem atics, NCERT, was a lways willin g to help u s in ou r en deavour in every possible way.

We welcome su ggestions an d comm ents from ou r valu ed u sers , especial ly s tu dents an d

teach ers. We wish our you n g readers a h ap py jour n ey into th e exciting r ealm of ph ysics.

A. W. J OSHIChief Advisor

Textbook Developm ent Comm ittee

xii

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CONTENTS

FOREWORD v

PREFACE xi

CHAPTER ONE

ELECTRIC CHARGESAND FIELDS

1 .1 In t rod u ct ion 1

1 .2 E lect r ic Ch a r ges 11 .3 Con du ctors a n d In s u la tors 5

1 .4 Ch a rgin g by In du ct ion 6

1 .5 Ba s ic Prop er t ies of E lect r ic Ch a rge 8

1 .6 Cou lom b s La w 1 0

1 .7 Forces b etween Mu lt ip le Ch a rges 1 5

1 .8 E lect r ic F ie ld 1 8

1 .9 Elect r ic Field Lin es 2 3

1 . 1 0 E lect r ic Flu x 2 5

1 . 1 1 Elect r ic Dip ole 2 71 . 1 2 Dipole in a Un iform Extern a l Field 3 1

1 . 1 3 Con t in u ou s Ch a rge Dis t r ib u t ion 3 2

1 . 1 4 Ga u s s s La w 3 3

1 . 1 5 Applica t ion of Ga u s s s La w 3 7

CHAPTER TWO

ELECTROSTATIC POTENTIALAND CAPACITANCE

2 .1 In t rod u ct ion 5 1

2 .2 E lect ros ta t ic Poten t ia l 5 3

2 .3 Poten t ia l du e to a Poin t Ch a rge 5 4

2 .4 Poten t ia l du e to a n E lect r ic Dipole 5 5

2 .5 Poten t ia l du e to a Sys tem of Ch a rges 5 7

2 .6 Equ ip ot en t ia l Su r fa ces 6 0

2 .7 Poten t ia l En ergy of a Sys tem of Ch a rges 6 1

2 .8 Poten t ia l En ergy in a n Extern a l Field 6 4

2 .9 Elect ros ta t ics of Con d u ctor s 6 7

2 . 1 0 Dielect r ics a n d Pola r is a t ion 7 1

2 . 1 1 Ca p a citors a n d Ca p a cit a n ce 7 3

2 . 1 2 Th e Pa ra llel Pla te Ca p a citor 7 42 . 1 3 Effect of Dielect r ic on Ca p a cita n ce 7 5

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2 . 1 4 Com bin a t ion of Ca pa citors 7 8

2 . 1 5 En ergy S tored in a Ca pa citor 8 0

2 . 1 6 Va n de Gra a ff Gen era tor 8 3

CHAPTER THREE

CURRENT ELECTRICITY

3 .1 In t rod u ct ion 9 3

3 .2 E lect r ic Cu r r en t 9 3

3 .3 Elect r ic Cu r ren t s in Con d u ctor s 9 4

3 .4 Oh m s la w 9 5

3 .5 Drift of Elect ron s a n d th e Or igin of Res is t ivity 9 7

3 .6 Lim ita t ion s of Oh m s La w 1013 .7 Res is t ivity of va r iou s Ma ter ia ls 101

3 .8 Tem p era tu re Dep en den ce of Res is t ivity 103

3 .9 E lect r ica l En ergy, Power 105

3 . 1 0 Com bin a t ion of Res is tors Ser ies a n d Pa ra llel 107

3 . 1 1 Cells , em f, In tern a l Res is ta n ce 110

3 . 1 2 Cells in Ser ies a n d in Pa ra llel 113

3 . 1 3 Kirch h offs La ws 115

3 . 1 4 Wh ea ts ton e Br id ge 118

3 . 1 5 Meter Br id ge 120

3 . 1 6 Pot en t iom eter 122

CHAPTER FOUR

MOVING CHARGESAND MAGNETISM


4 .2 Ma gn et ic Force 133

4 .3 Motion in a Ma gn et ic Field 137

4 .4 Motion in Com bin ed Elect r ic a n d Ma gn et ic Fields 140

4 .5 Ma gn et ic Field d u e t o a Cu r ren t E lem en t , Biot -Sa va rt La w 143

4 .6 Ma gn et ic Field on th e Axis of a Circu la r Cu rren t Loop 145

4 .7 Am peres Circu it a l La w 147

4 .8 Th e Solen oid a n d th e Toroid 150

4 .9 Force between Two Pa ra llel Cu rren ts , th e Am pere 154

4 . 1 0 Torqu e on Cu rren t Loop , Ma gn et ic Dipole 157

4 . 1 1 Th e Movin g Coil Ga lva n om eter 163

CHAPTER FIVE

MAGNETISMAND MATTER


5 .2 Th e Ba r Ma gn et 174xiv

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5 .3 Ma gn et is m a n d Ga u s s s La w 181

5 .4 Th e Ea r th s Ma gn et is m 185

5 .5 Ma gn et is a t ion a n d Ma gn et ic In ten s ity 189

5 .6 Ma gn et ic Proper t ies of Ma ter ia ls 191

5 .7 Perm a n en t Ma gn et s a n d E lect rom a gn et s 195

CHAPTER SIX

ELECTROMAGNETIC INDUCTION


6 .2 Th e Exper im en ts of Fa ra da y a n d Hen ry 205

6 .3 Ma gn et ic Flu x 206

6 .4 Fa ra da ys La w of In du ct ion 207

6 .5 Len zs La w a n d Con s erva t ion of En ergy 210

6 .6 Mot ion a l E lect rom ot ive Force 212

6 .7 En ergy Con s id era t ion : A Qu a n t it a t ive S tu d y 215

6 .8 Ed d y Cu r ren ts 218

6 .9 In d u cta n ce 219

6 . 1 0 AC Gen era tor 224

CHAPTER SEVEN

ALTERNATING CURRENT


7 .2 AC Volta ge App lied to a Res is tor 234

7 .3 Representation of AC Current and Voltage by

Rota t in g Vectors Ph a s ors 237

7 .4 AC Volta ge App lied to a n In du ctor 237

7 .5 AC Volta ge App lied to a Ca pa citor 241

7 .6 AC Volta ge Applied to a Ser ies LCR Circu it 244

7 .7 Power in AC Circu it : Th e Power Fa ctor 252

7 .8 LC Os cilla t ion s 255

7 .9 Tra n s for m ers 259

CHAPTER EIGHT

ELECTROMAGNETIC WAVES


8 .2 Dis p la cem en t Cu r ren t 270

8 .3 E lect rom a gn et ic Wa ves 274

8 .4 Elect rom a gn et ic Sp ect ru m 280

ANSWERS 288

xv

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COVERDESIGN(Ada pted from h ttp :/ / nobelprize.org an d

th e Nobel Prize in Phys ics 200 6)

Differen t st ages in t h e evolu tion ofthe u niverse .

BACK COVER(Ada pt ed from ht tp :/ / www.iter .org an d

h ttp :/ / www.da e.gov.in)

Cu t a way view ofInternational Thermonuclear Experimental Reactor(ITER)

device. Th e ma n in th e bottom sh ows the scale.

ITER is a joint international research and development project that

aims to dem ons tra te th e scientific an d tech nical feas ibility of fu sion power.

Ind ia is on e of th e seven fu ll par tn ers in th e project, the oth ers being

th e E u ropean Union (repres ented by E URATOM), J ap an , th e Peoples

Repub lic of China , the Repu blic of Korea, the Ru ssian Federation an d th e

USA. ITER will be constructed in Europe, at Cadarache in the South of

Fra n ce an d will provide 5 00 MW of fu sion p ower.

Fus ion is th e energy source of the su n a nd the s ta rs . On ear th , fu s ionresearch is a imed a t demons tr a t ing tha t th is energy source can be u sed to

prod u ce e lect r ic ity in a sa fe an d en viron m ent a l ly ben ign way, with

abu nd an t fu el resour ces, to meet the n eeds of a growing world popu lation.

For details of Indias role, see Nuclear India , Vol. 39, Nov. 11-12/

May-J u n e 200 6, issu e availab le at Dep ar tm en t of Atom ic Energy (DAE)

website ment ioned above.

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Firs t Edi t ionDecemb er, 2006 Paus a 19 28

Repr in ted

Decemb er, 2007 Agraha ya na 19 29


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