BACHELOROF SCIENCE(B.Sc.) T@-End Examlmtion December, 2OOa PHE-7: ELECTFIC & MAGNETIC PHENOMENA
All queslions nre conpui€orl' Morks question oUorba lat eoch dte indi.oted asdinsr it. vau hdy 6e Io9 tables or o cd/.uidfor SvDboh ho@ then usual
1,
AnefrpLanv./iu€ paft> (i)
5,.3:15
T!€ €l€.hic field in a cenainrcsion ot spa.e is
si"o by i
: r5o i. Howmuchfluxpass
thbush an ar@ A if it k a ponion ol (a) lhe (b) tn€ v pran€ and k) rha 4,"prde, (ii) lI the €lectriclield equalszero at a siven plinl, do6 it nec6saril, inply thal th€ potenlial must alsob€ zro at that point ? Explaintour answerby givingone exanple
(iii) A diele.lric havingrelatiw perhiriMly 6 lills the mleruning space bel*een th€ pLalesoI a parall€fplatecapacirorinst€adol aii Darermine th€ lactor by which th€ opacitance and elatic liv) Sketch the electic li€ld iside and outsid€a unitornly chaigedspheie. (v) Explain why a r6isring io..e is dperienc€d whe! a copper sheet is pushed/puled in a {vi} A .1,1€d (@nt,oop i, pra€d in a magleti. field. Write d@n the ape$io.s tor rhe magnebcdrpol€noh€dt ol $e cunmt loop and the torque qperi€led bv it. A circularloop ol wne ol ladiu 6 0 cn cocists oi 15 lurtu of wir€. A cuftni of 2 0 A ios through the Nire loop. Wiat is rhe magntird€ ot the magnelicmomentof the loop ? (vji) Explaintie pnnciplamdeiyins the desisnol a nep doq ka6tome. Afremp'dy tiu€ paas (i) Two paellel plar6 ol ara 2OO02 aE si@n a1ul and oppositechars€ ol 3 O x tO 7 C Th€ spa.e bel*€en the plal€s is Jil,€dwi!'r a dier€clricmaterial and the elednc n€ld willin op di€lecrlicis 4.3 x 1OsVh 1. what is lhe di€lecrric 66ranr oI th€ dtelednc and lhe
[email protected] densnyon the plate ? Takeo. = 8 85, to-12 c2 N-lm2,
(it
Show lhat the norml component of E is di$onrinuou acro$ a dialachicboundary.
liii) A charse-q mo6 w h a speed, in a circularpalh oi radi6 r @nt.red on a charse +q Deduce an expressionlor lh€ eliective cu(ent and lhe masn€ti. moment ll. liv) A unirormlychargeddisc havins lhe charse q and radiusr is rotatingwith a constantansLnar spe€do. Sbow that the magnelicdipol€ h$t haw rhe nasnirude
;
(s o r).
(v) A loroid ot aluminium ol length 1 m ol 1000 hM ol wire k carryinsa st@dycurent ol I A Th€ msnelic liela in lh€ toroid is loud to b€ 2 512 x 10 3 wbn-2. Det€mine ,(fr, the @g@iic su$eptibility. Takero=4nr10/NA-. (!i) The pole faes of the magn.ls ol a cyclolrcn 6ed to acc€lelate protons are 125 cn in diamelr. The lield bet een the pol€ lacas is 0 90 r Cahlate the kineiic ddsy tn ev and the speedol a pblon as it emelgestom the cyclotron. Determine the f!€qu@ry of the alternatingrcltase that nul be appli€dto lhe D.es ot the cyclokon. (np = 1 67 ' tO 27 kg and1eV=16:t(IleJ)
3.
Andfl (i)
&y ore palt :
A plale €l€ctromasneticwaw ol lrequ€ncy 200 MHz
lravellins in
hdm
stirkes
nornaly rbe surfaceof a block of a mabnal h a v i n s€ = s o , [ = 9 r o a n d o = 0 . r the incidmt elednc Iield wctor is giwn h! E = 3.s .ohplet€
(o, - 0ri Vm', wdt€th€ dpre$ions for the incid€li,
r€flecled and tratuditled masneticIield v€.lo$.
elacl.c
and 2+4+4
(ii) Show lhat th€ eleclric lield an'i tle potential due to an ele.tlic dipole al a point lary d l 1 ano r€spa.rwry lompaP rne 2 -, ie$lts wilh charse.
those
obtain€d lor a point 4+3+3
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al 'rF..q5ql (evi) eJr lrd 4 !q{ al I {'a_fiireii * "31" !1 !flliltud{dr{fi +sdr d qqii d wrir 4i (np = 167 x 10127ks dqr
irdld I {qftn gs 2oo MHzqr?F qrd B&jr4lq ni.r, q6 Fqr{ + "rfrd a6i qi {d? !{ aq-tr( qrqftn iidi i I c s d+ f i q e = e . , p = e p o 3 r t a = o i I qfs srqftn kS(-& stlr ; ' 3 t.r - 0!) l v-r ii, a qcftd, "* s{slid 3i{ iqfid ftqE $i g4dq 47 {ffi + €t"l | 2+4+4 "is-6 ftid (jt
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