VIEWS: 348 PAGES: 11 CATEGORY: High School POSTED ON: 5/8/2012 Public Domain
I Series : SMAIl I .~. Code No. 55/1/2 Wro:i'. ~-~ lfSf-~ o/~ml Roll No. Candidates must write the Code on the title page of the answer-book. - • ~\ifTqCR"Bfcp~~--q;f-q:~~l1 ~ I • ~--q;f-q:~~cn1am-~TW.~Cf?T~~-~~lfSf-~o/m I • ~ \ifTqCR"B fcp ~ ~--q;f -q:30 ~ ~ I • ~~COT~fM&'1I'Wm--«~, 'fi;ref ~COT~amcr I • ~ ~--q;f ~ Cf?T ~~ 15 fi:f:R."CfiT ~ W:rr 'FIT %" I ~--q;f CfiT ~ ~ -q: 10.15 ~ ~~ 110.15 ~~ 10.30 ~('jCf)~~~--q;f~~~~~~~~- ~o/C!?Tt~~~ I • Please check that this question paper contains 11 printed pages. • Code number given on the right hand side af the question paper should be written on the title page of the answer-book by the candidate. • Please check that this question paper contains 30 questions. • Please write down the Serial Number of the question befo re attempting it. • 15 minutes time has been allotted to read this question paper. The question paper will be distributed at 10.15 a.m. From 10.15 a.m. to 10.30 a.m., the students will read the question paper only and will not write any answer on the answer script during this period. ~fq~I~(~) PHYSICS (Theory) ~ WFl " 3 CTUtJ [~3icFi,' 70 Time allowed " 3 hours J [ Maximum marks,' 70 fll¥OIl"'<4 ~ : (i) ~ JIR 3ff.:rcrrcf t I (U) if ~ JIR-TT;T Tf7 30 JIR t I JlRl '# 8 ('fCf)cFJIR 3lfrr-HCJ3f1<72f JIR t dK ~ 'f!C1' 3icFiw tI (hi) JIR 9 '# 18 if ~ JIR ~ 3icFiw t, JIR 19 '# 2 7 if ~ JIR rftr:r3icFiw t ff'2lT JIR 28 '# 30 if ~JIR rikr3icFiw tI 55/1/2 1 [P.T.O. (iv) JlH-W if ~ w <Nt fclcnc;q;rif t I ~ et 3fcfiT crwf 'f!?Ii"JlH if, rft;:r 3fcfiT crwf 'f!?Ii" JlH if 3#r t rif.q 3fcfiT crwf M JlRf if 31fPf1RCh qq;r "WF1 fcl;<:rr T{<:fT I # JlRf if 3flTTcIiT m 7J<l qq;r if -# cFwr 'f!?Ii" lH it CfiRT t I J (v) ~ft'iwk< c1;" ~ qfj- ~ -;:rti. t I ~ ~ 31fCl~4Ch ~ rrT 3[JTJ ftEJ'fU/Ch74 W(U{t CfiT mCfi(~t I (vi) ;;rif 31fClNCh ~ 3[JTJ RAfMf@H ~ R4HiChT c1;"7fFif CfiT ~ Cfi( ~ t: c = 3 x 108 m1s h = 6.63 x 10-34 Js e = 1.6 x 10-19 C 110= 41t X 10-7 T mA-1 _1_ = 9 x 109 Nm2C-2 41tEo me = 9.1 x 10-31 kg General Instructions : (i) All questions are compulsory. (ii) There are 30 questions in total. Question Nos. 1 to 8 are very short answer type questions and carry one mark each. (iii) Question Nos. 9 to 18 carry two marks each, Question Nos. 19 to 27 carry three marks each and Question Nos. 28 to 30 carry five marks each. (iv) There is no overall choice. However, an internal choice has been provided in one question of two marks, one question of three marks and all three questions of five marks each. You have to attempt only one of the choices in such questions. (v) Use of calculators is not permitted. However, you may use log tables ifnecessary. (vi) You may use the following values of physical constants wherever necessary : c = 3 x 108 m1s h = 6.63 x 10-34 Js e = 1.6 x 10-19 C 110 = 41t x 10-7 T mA-l _1_= 9 x 109 Nm2C-2 41tEo me = 9.1 x 10-31 kg 1. fcfim ~ ~ Cf)f WR ~ ~, ~ ~ ~ 1R, ~ ~ ~ MklCl(1 ~ -rnr ~? 1 Why must electrostatic field be normal to the surface at every point of a charged conductor? .~ ~ ~ it ~ ~ 31qClct'"liCfl Cf)f ~ ~, fcfim ~ it ~ 1R cpfq cit ~ ~ \J' ~~~~? 1 . ~r what condition does a biconvex lens of glass having a certain refractive index act as a plane glass sheet when immersed in a liquid? . 55/1/2 2 3. ~-?~ qRCh(v<HI.mCf1T~ I 1 7e de-Broglie hypothesis. 4. ~ ~ ufuq1f 1111 ~ ~ f.:rq-ffi if l1R, 1 mm crtrr ~ ~ ~~ ri ~ 1600 A ~ q{I~1111 ~fCfi{On *,mW1FfWffi~ I ' 1 ~ the physical quantity which oremains same for microwaves of wavelength ~:: and UV radiations of 1600 A in vacuum. 5. 00 ~ if ~JlctS;111q1f f.1q ~ ~ ~ fcrqq ~ am- ~ ~ t CflIT~ ~ ~ <:j1f ~ *'~ ~JlCf';}l ~ m fwTif Tffu CR 'W t ? - 1 ~~~ electrons drift in a metal from lower to higher potential, does it mean that all the free electrons of the metal are moving in the same direction? 6. ~TT<t ~if~~~, ~~fwTif~~I~m~~ I ~~TT<t~*' CR¥f (WT) Cf1T~ ~ ~ -31Tt ~ WR Wr v ~ ~ ~ ill CR¥f if m~ ~ ~fwT CflIT~? 1 ~O v I ) Predict the direction of induced current in a metal ring when the ring is moved towards a straight conductor with constant speed v. The conductor is carrying current I in the direction shown in the figure. ~O v I ) ~ ./ 00 ~ lR" ~ *' 1k1Cf?l4 ~ q1f ~ ~ B ~ ~ ~ 60° ~ I ~ lR";p:f1 CfiTuT lR" ~*'1k1Ch14 ~*,~~q1fl1R~WTT? 1 The horizontal component of the earth's magnetic field at a place is B and angle of dip is 60°. What is the value of vertical component of earth's magnetic field at equator? 1 Show on a graph, the variation of resistivity with temperature for a typical semiconductor. 9. OO~~ 'Q' ~~ 'r' *,~, (i) ~~ (E) ~(ii) ~~ (V) *,QRClct'1 \ 00 *,m.~-mrn (~) ~ Cf1T I 2 Draw a plot showing the variation of (i) electric field (E) and (ii) electric potential (V) with distance r due to a point charge Q. ' 55/1/2 3 [P.T.O. 2 rive the expression for the self inductance of a long solenoid of cross sectional area A and length I, having n turns per unit length. J. '!iRr t- f<I>m ""'''TS llf;<r t- ~ ~..mv, ~ fcRur, fu\TI1 'I>f 3lq"J~i'b 3lfi:lR ~ ~ --J3 t I W 'R 3l1'lfffir WIim qi\ '"'" (11,) ~ ~41'"f1< TflFf W t 01,~ fcRur cpr~ cp)ur '2-- fcRRT WIT ? 2 /ray oflight, incident on an equilateral glass prism (Ilg = -f3) moves parallel to the base line of the prism inside it. Find the angle of incidence for this ray. ~ f<;fuq;- 'I1'ffi -It ~ 3llf 'Iffi 'I>f'IFf (- mA), q,,,f,\!il'b 'I1'ffi -It ~ 'Iffi t- 'IFf (- I1A) "i\ ~-wrrt I o1ftR-~~cpr~ q~:qf~f:(ICfl~#~m-r\ifRfTt? 2 'T'~ current in the forward bias is known to be more (-mA) than the current in the ", ~ l z»: JU'-' reverse bias (-IlA). What is the reason, then, to operate the photodiode in reverse bias? /" f,gF~G~ (~ (Mf l{11~111(~ ~ # -3RV (~Wrfur<t I 2 ~ ~~#, f-ij:;jf<jjf@ct #~Gl~~cpr~~ I (i) ~1~~lm (ii) fttfRr ('i1<lq~Cfl) (iii) ~1~JOOtlG< ~ (iv) ~~~ Distinguish between' Analog and Digital signals'. OR Mention the function of any two of the following used in communication system: (i) Transducer (ii) Repeater (iii) Transmitter \ (iv) Bandpass Filter \ The susceptibility of a magnetic material is 2.6 x 10-5. Identify the type of magnetic material and state its two properties. 55/1/2 4 ~ ~ ~ cpr ~ ~ ~ ct.~.~.) E ~ alH1RCfi ~ or' ~ I ~ ~ CfiT ~ ~ ~ RI ~ R2 (MT ~ ~ ~ ~ ~ ~ TT<n I ~ -q:~ cpr l1R f":P:iifCf)\I ~ ~ ~ -q: l1TITI TT<n : ~ 2 (i) \ifGf ~ -q: Cf# ~ ~ 1if ~ I \ f (ii) \ifGf ~ -q: ~ RI ~ ~ I (iii) \ifGf ~ -q: RI (MT R2 ~ ~ -q: fi41f~ct t I (iv) \ifGf ~ -q: RI (MT R2 m (fPiict{) ~ -q: fi41f\i1ct t I 3q{1CR1~~ ~ -q: mu.:if ctl1R, 0.42 A, 1.05 A, 1.4 A (MT 4.2 A t I~, ~ allq~lICfi 1if ~ % ~ mu.:if ~ ~ l1R 3Q{1CR1~ ct ~ -q:it m I W, 3Q{1CR1 ~~ctm~-q:~ muctl1RqiT~~ I A cell of emf E and internal resistance r is connected to' two external resistances RI and R2 and a perfect ammeter. The current in the circuit is measured in four different situations: (i) without any external resistance in the circuit (ii) with resistance RI only (iii) with R] and R2 in series combination i I (iv) with RI and R2 in parallel combination The currents measured in the four cases are 0.42 A, 1.05 A, 1.4 A and 4.2 A, but not necessarily in that order. Identify the currents corresponding to the four cases mentioned above. 16. ~"Whm ii1ICfiI< ~ ~ P (MT Q -q: qiT ~ r~ ~ I~ ~~: 1 (MT 21 ~ ~m"@~ I<t~wriwB4ct(111R~t~~cpl~it~~t ~ '0' ~~1R~-q:~muqiT~~~~~ I~'O' ~~~WlR crt 1R~ I W ~ '0' iR ~ ij)~Cfllli ~ cpr l1R -mc=r ~ I 2 1j : ir 1 21 Two identical circular l~ and Q, ~h Of~~nd carrying currents I 1 21 and 21 respectively are lying in parallel planes such that they have a common axis. The direction of current in both the loops is clockwise as seen from 0 which is equidistant from the both loops. Find the magnitude of the net magnetic field at point O. 55/1/2 5 17. 'L' ~cnT~'tffiIcnT~~, 'ro' ~ 3Wfn~~~~Cfi«ft~fcfi; ~~ ftro 'L' ~ ~ 'tffiI ~ ~ cWD ~ ~ If{ ~ ~ ~ afu- ~ ftro cwr:r cnT~ CfWl If{ -mn ~ I ~ cnT~ ~, cWD ~ ~ ~ ~ ~ ~ afu- cwr:r ~ ~ CfWl ~ c:1kfCl~ ~ I~ ~ ('MT ~ w:rR T:{kfChlll B, 00 fCl'WiH ~ I CfWl cWD ~ ~ ~ ('MT CfWl ~ ~.~.~. ~~~~m~~~~ I 2 J.. metallic rod of 'L' length is rotated with angular frequency of 'ro' with one end -...'hinged at the centre and the other end at the circumference of a circular metallic ring of radius L, about an axis passing through the centre and perpendicular to the plane of the ring. A constant and uniform magnetic field B parallel to the axis is present everywhere. Deduce the expression for the emf between the centre and the metallic nng. /. ~~~~cpT~m.m. ~ ~~~~M\1fRIT~"illC1#~ ~ ~ mill, ~, ~.m. (~f4ICldl) ~ Wo ~ Cf?f ~ If{ ~ c:111i("11{ ~ mill ~ ~ I ~-~ cnTBCf)0FtI~ 3Wm" If{ ~ cxn&:rr~ cnT\ifT ~ ~ ? 2 ~en an ideal capacitor is charged by a de battery, no current flows. However, when y an ac source is used, the current flows continuously. How does one explain this, based on the concept of displacement current? I 19. ~*~Cf?f~~0R" AB ~TT<ITt ~~~~~~f.:r:«:r (-3iqRCldl)F.fqqW5fUfc1T rmD ~ I ~~~cpT, ~~~~ (t~.~.) 8 1 ('MT 82 t, ~*~'Pl~B41P~ctMTT<IT~ I~m~~~(~ ~ A fut ~ 120 em ('MT 300 em ¢ If{ ml:C1" mill t I "ill~ ~ (i) 8/82 (ii) ~E1~m~~W&r(~~cnT¢ I 3 ~ c cnTB~t;+~flc:1ctl pt ~ ~ ~ \1fRIT ? .----~ I II---"'VV'(/\I\,----, K---- 300 em ---+) I20cm~ A~-------:lr-----;!I:------,B £2 ~ fCfl{illCfi ~ f.:r<:p::ff Cf?f ~ ~ ~ ~ * ~ ~ RCf?f 1H ~~, 1 .4 n ~~C1#~~";{~ IAafu-D~~~Cf?fl1Hm~~ I I,Q E F D I,Q 4,Q R \ ' A IL C y" 9V B 3V 55/1/2 6 -, In the figure a long uniform potentiometer wire AB is having a constant potential gradient along its length. The null points for the two primary cells of emfs El and E2 connected in the manner shown are obtained at a distance of 120 em and 300 ern from the end A. Find (i) E/E2 and (ii) position of null point for the cell El. How is the sensitivity of a potentiometer increased? .----ll II---JV\J'I(/\/\~---, 1E---300cm --~) 120cm~ A \----------:.--~r_----'B OR sing Kirchoff s rules determine the value of unknown resistance R in the circuit so that no current flows through 4 n resistance. Also find the potential difference between A and D. In E ~, F~~~-?----~D In R I 6V A ~ C ~ 9V 3V JO. ~ (fq;f) "# ~ l1<l ~, ~ ~ LCR ~ "# L = 4.0 H, C = 100 /-IF ('Mf R= 60n~ I W 240 VCfIT~ ~~~~~t"ffi QRctI(>'1'"1 ~ 3 / R (i) . 9:, +c ~CfIT~ 3Wfn~ ~o/~cn1 L QRillfc;>1~ ~~ I (ii) ~ 3Wfno/~"CfITl1R (iii) ~o/m~fmt ~~ q7f l1T'&flFf (3W.~.~.) fcrqq--qffi A series LCR circuit with L = 4.0 H, C= 100 /-IFand R = 60 n is connected to a variable frequency 240 V source as shown in. R 'T t: '2 +0 -v - ~ :, fc L q::v~24-0 V :1,,:::0 ~_aJyulate : ~ _ the angular frequency of the source which derives the circuit at resonance; ~ the current at the resonating frequency; ~1) the rms potential drop across the inductor at resonance. 55/112 [P.T.O. 21. (-31) -mm ~f('jCfi{UI >W<1 ~ c)?Wrt CfiMlfiCSl<>s m Cf?T~ CflIT3ilq~'4Cfi t? 3 (~) <:ill c)? 00 W-MU-wWT -q A. ct<II~c4 c)? QCfiqUnw:pm ~ Cf?T ~ ~ .-p:rr t I ~~c)?~~lR~~ A. t w:pmCfftmwrr K ~~ t I ill, ~ ~ lR w:pm Cfftmwrr -mct"~ ~ lR ~ 231.. t I ~ Why are coherent sources necessary to produce a sustained interference pattern ? (b) In Young's double slit experiment using mono-chromatic light of wavelength \ A.,the intensity of light at a point on the screen where path difference is A.,is K units. Find out the intensity of light at a point where path difference is 231... 22. 00 2 em x 5 em ~c)?~3iI'4ctICfiI{ 'lm ~ ~ 1 A Cfft~~m~t I. m -q ~ "JTit ~ ~-mm ~ (fR, ~ 4A Cfft'i:ffiT ~ m ~ t, ~ 'lm ~ c)? RcRWmt 1<W(fRafu-'lm~m-~-qmill-mct"~: 3 (i) 'lm ~ lR ~ ~-~ (iTcfi)CflIT (ii) (fR -q ~ ~ 'i:ffiT c)?cmuT, 'lm lR wR m~ Cf?Tl1R CflIT ~ ~ I 1=4A !E--2ern ~ 5 ern lA ~ lern /rectangular loop of wire of size 2 em x 5 ern carries a steady current of 1 A. A straight long wire carrying 4 A current is kept near the loop as shown in the figure. If the loop and the wire are coplanar, find (i) the torque acting on the loop and (ii) the magnitude and direction of the force on the loop due to the current carrying wire. I=4A !E--2ern~ 5 ern lA / lern J3. C ¢i1~'i\l;<OI~'i f?T w:pm-~ ~141Cfi<ul~ I~ ~ Cfft ~ ~14ICfi{UICfiT~-ijl:~Ff)l'4 n fClfCf){u c)? 1:!iliH-m c)?~ mu ~ >W<1 fcn<:rr ~ ~ t ? 3 w:pm ~ ~ c)?&T ~ ~ Cf?T ~ ~ ~ ~ c ~141Cfi{UI)?~ ~ 1 ~Cfft~~t I \ /V fit instein's photoelectric equation. State clearly how this equation is obtained usi g the photon picture of electromagnetic radiation. rite the three salient features observed in photoelectric effect which can be explained using this equation. 55/1/2 8 24. (31) ~ ~ cnm ~ ~ ~ *l1...aCf){UI ~ ~ ~ ~ ~ ~ ~ fcp t\1$~l\iH cpl- ncff cnm Wffi:r"#, $JlCf~I"i cpl- m CfiT11R ~ ($JlCf~I"i ~ ~ 61- ~ i1{II~~ ~11R CfiT lfIT n m-m t I 3 0f) M t\1$~hH 1WfTUl "# ~ $JlCf~I'i ~ "# mmT ~ ~ "# t I~ ~ $JlCf~I"i -3llFft f-"18i14 ~ (~ ~ "# ~ ~ 01 ,ikfl%'j(1 m ~ ~ ~Cf~41 00,* ~~~~~? \ 1/v-- $ Using Bohr's second postulate of quantization of orbital angular momentum show that the circumference of the electron in the nth orbital state in hydrogen atom is n times the de Broglie wavelength associated with it. . (b) The electron in hydrogen atom is initially in the third excited state. What is the maximum number of spectral lines which can be emitted when it finally moves to the ground state? r; <\\ 'r : ,.... j..- r» '" > 'r-. r-";"- oj "l.- tr'< - .,..,..." 25 .. ~~~~~~M~fuRl"ffiT~~~cpl-an&rT~, ~fuRl yV\.V ' QCf)qUnwmT~"ffiT~t I 3 ~ fuRl cpl-~ CfiT ~ ~~ ~ ~ lfIT cpr ~ ~ 01, ~ ~ ~ ~~ (MT ~ 1K ~ W1TCr ~ ? ifuse Huygens's principle to explain the formation of diffraction pattern due to a ~(-v single slit illuminated by a monochromatic source oflight. When the width of the slit is made double the original width, how would this affect the size and intensity ofthe central diffraction band? 26. (i) 1WfTUl~ (A) ~30 q 170 ~~l1RT, ~m,>rfu~aWr~~ (BElA) ~ 11R ~ WR w-f cpl-an&rT '"{CR114~ ~ ~ ~ lJUT~"ffiT cpl-\ifT"fICfiffi t ? (ii) ~ fcp~ ~~~~"# ~CfiT"f.R("q WR (f.=r:m) mT t ~~ -. S::044H ~ (A) 1K~ (-31lf~ ~ m-m I 3 (i) What characteristic property of nuclear force explains the constancy of binding energy per nucleon (BElA) in the range of mass number 'A' lying 30 < A < \1 170 ? A. \ ).....--- how that the density of nucleus over a wide range of nuclei is constant- independent of mass number A. y. ~ ~ ijklCf)14 ~-~ Wlll ~ ~ cpl- m ~ cpl- Wlll ~ ~ ~ ~ m~ (fqm~ ~ ~ m CfiT~ fu:!furt anW cpl- ~ I 40 MHz ~ ~ cruR ~I 3 P. ~vName the three different modes of propagation of electromagnetic waves. Ex,plain, using a proper diagram the mode of propagation used in the frequency range above 40 MHz. 55/112 9 [P.T.O. ~ ~<<;~\Cf)cnl~WffiTcnl~('MT~m~~ I . 5 V 00 -rnt *" ~<<;~\Cf) ~ -31tt~ cnl ~ ~~: 150 em ('MT 5 em t I~ ~<<;~\Cf) 3 km ~ ~ W:rn-, 100 m ~ GfC.f{fiT ~ C ~ ill ~ ~fdPcilklcnl ~ ~ WIT ~~fdPcilkl ~~ 25 em ~o/~ I ~ ~~m cnr~ ~<<;~\Cf) ~ *" ~ fcR1 WfiR ~ mm t ? oo~*"~('MT~cnl~~~: 1.25 em ('MT 5 em t I ~ 30 ~ ~ m"{{f CflB *"m. ~ cnr~*" ~&1 wmr Frtl\fu;~, ~ ~~cnr~cmit~~~ fcrnT~t? BI41'""l1ct: $efine magnifying power of a telescope. Write its expression. A small telescope has an objective lens of focal length 150 em and an eye piece of focal length 5 cm. If this telescope is used to view a 100 m highJtower 3 km away, find the height of the final image when it is formed 25 em away from the eye piece. OR How is the working of a telescope different from that of a microscope? The focal lengths of the objective and eyepiece of a microscope are 1.25 em and 5 em respectively. Find the position of the object relative to the objective in order to obtain an angular magnification of 30 in normal adjustment. CE fcRmllf 00 s;ir-ijR'<~ *" m~ ~ ~ ~ ~ I~ -cnrt ~ CfiT ~~ I ~~fcl?~~cnl~~ Ay = - PacRL, ~ Pac - 'i:ffiT~, rj RL -~~('MTrj-Rcm~t I 5 ~ ~ *"m ~*" ~cnr 5fi\l11,4Cf) cp;rr ~ t? . ~ (-31) ~ ~ ~ "ctirr ~Cf)I~1 *" m ~ ~ ~ f\ifwf p-n ~ ~ cnr~ ~ m TT<:fT I ~ -cnrt ~ CfiT ~ ~ ('MT~ -31ttWRi "ctirr ~ CfiT ~ I (~) mm A f'"18ifCflct -31ttB *"m WRi"ctirr"{C\q" (Y) CfiT ~ : (i) OR ~ ('MT (ii) NAND ~ tl t2 t3 t, t8 I I I I I I I I I I I I I • I Ai-' ----I I I I I I I I B;----- I I I I Draw a simple circuit of a CE transistor amplifier. Explain its working. Show that the R P voltage gain, Ay, of the amplifier is given by Ay = - a;. L, where Pac is the current 1 gain, RL is the load resistance and rj is the input resistance of the transistor. What is the significance of the negative sign in the expression for the voltage gain? OR 55/1/2 10 ~ e ~ Draw the circuit diagram of a full wave rectifier using p-n junction diod.." :.,.<. Explain its working and show the output, input waveforms. . .? ~ (b) Show the output waveforms (Y) for the following inputs A and B of t \ (i) OR gate (ii) NAND gate tl t2 t3 t4 t5 t6 t7 t8 I I I I I I I I I I I I I I I I I I Ai-I ----4 I I I I I I I B;----- I , I ~ v~~ ~tl cl;'~ cR ~ ~ ~ ~ fYf~4'i cITR-W CfiT~ ~ ~ m 5 ~ ~ cpr ~ 41;)'1'"1161(1 ~ ~ ~ ~ CflI~fqM-cR ~ ~ 1cp:rr~ ~ WI ~~~CfiT3~il(14~'RcnTt~mnrt?~~ 1 ~ (31) ~~CfiT~~ I~~.~. (S.I.)~cp:rrt? 0D ~ cl;'f.:l<:rqcl;'~ WI ~citm fcfl, 00 ~~ ~ ~~ ~ ~ -we ~ 0 cl;'"CflRUT 0 ~ 'R ~ ~ cpr "48, ~ ~ ~ ~ ~ CfiT 'R f.Mr~ mnr 1 (tl) ~ ~ ~ CfiT cp:rrmrrr, ~-we ~ (i) 'tHI~f:(l(1 m (ii) ~1I~f:(l(1 m ? Explain the principle of a device that can build up high voltages of the order of a few million volts. Draw a schematic diagram and explain the working of this device. Is there any restriction on the upper limit of the high voltages set up in this machine? Explain. _ ~ / OR ~ --- Defme electric flux. Write its S.L units. Jl1) Using Gauss's law, prove that the electric field at a point due to a uniformly charged infinite plane sheet is independent of the distance from it. ~ How is the field directed if (i) the sheet is positively charged, (ii) negativJl ;7 charged? '\ 55/1/2 11