physics cbse 2010 board paper

I Series : OSSII I Code. No. 55/1/3m-;r.Roll No.mr-r.

Candidates must write the Code onthe title page of the answer-book.Wri~cR"3W-~cl>~-~lR~fu-@ I

• Please check that this question paper contains 12 printed pages.

• Code number given on the right hand side of the question paper should be written on thetitle 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 before attempting it.

• 15 minutes time has been allotted to read this question paper. The question paper will bedistributed at 10.15 a.m. From 10.15 a.m. to 10.30 a.m., the student will read the questionpaper only and will not write any answer on the answer script during this period.

• ~~CRBfCfl~~-ta-q~~12t I

• ~-~-q~~c€r~~~~~cR"€ffi""3W-~cl>~-~lRfu-cl1

• ~~CRBfCfl~~-ta-q 30 ~t I

• ~~CfIT"3Tff~~m-«~,~~~~~ I

• ~ ~ -ta cR ~ cl>fur!: 15 fl:Rc: cnrw:r:r K<n" "l"flIT t I ~-ta cnrfcf~-{UflicriFf -q 10.15 ~ ~~ 11O.15~-B-10.30~(fCfi"€ffi"~~-tacR~~~~cl>~~"3W-~lR~~~~1

PHYSICS (Theory)

~fct#1lY1 (~)

Time allowed: 3 hours }f.:mffur "R7PJ : 3 FJUtJ

[ Maximum marks: 70[~3:fcr;: 70

General Instructions:(i) All questions are compulsory.(it) There are 30 questions in total. Questions 1 to 8 carry one mark each, questions 9 to

18 carry two marks each, questions 19 to 27 carry three marks each and questions28 to 30 carry five marks each ..

(iii) There is no overall choice. However, an internal choice has been provided in onequestion of two marks, one question of three marks and all three questions of fivemarks each. You have to attempt only one of the choices in such questions.

(iv) Use of calculators is not permitted.

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(v) You may use the following values ofphysical constants wherever necessary :

c = 3 X 108 ms "

h = 6.626 X 10-34 Js

e = 1.602 x 10-19 C

llo = 4n x 10-7 T m A-I

1-- = 9 X 109 N m2 C-24nEo

Mass of electron me = 9.1 X 10-31 kg

Mass of neutron mn == 1.675 x 10-27 kg

Boltzmann's constant k = 1.381 X 10-23 J K-1

Avogadro's number NA = 6.022 X 1023 mor '

Radius of earth = 6400 km

fll'IIO<l ~:

(i) ~ JrR" 3#rcrrzf t I(ii ) m- JTR- r[5P1 TM 30 JrR" fr I JrR" 1 "# 8 if Jlr!lcf; JrR" f!'fi 3fq:; CfiT t, JrR" 9 "# 18 "Ii Jlr!lcf;

JrR" et 3fq:; CfiT t, JnT.7 19 "# 2 7 "IiJlr!lcf; JrR" rft;:r 3fq:; CfiT t rmr JnT.7 28 "# 30 "Ii Jlr!lcf; JnT.7rmr 3fq:; CfiT t I

(iii) JnT.7- q;r "Ii w:m rrr citi ~ ~ t I nmf[r, ~ 3M "CfTff f!'fi JrR" If, rft;:r 3M "CfTff f!'fi

JnT.7"Iiam rmr 3M CJlff rft;:ff!1Fif"Ii 3f1'"HRCf) "'f/7F{ WH fW:rr 7J<lTt I #!1Fif"Ii 3fTT!CfiT

~ rrit "'f/7F{ "Ii "# ~ T[CIf JnT.7 it CfiRT t I

(iv) 4Jf/'J'H2'< cF 3Vlifrr cit oqr:rfrr ~ t I

(v) ~ 31/CI'l'2JCf) gT J1Tf[ ~fisrrr ~ R4ft/Cf)/" * lfRf Cl?T3Vlifrr ct?r ~ t:c = 3 X 108 ms "

h = 6.626 X 10-34 Jse = 1.602 x 10-19 C

llo = 4n x 10-7 T m A-I

1-- = 9 X 109 N m2 C-24nco

~M<:fGI"icnlWfum = 9.1 x 10-31 kg~ c

~cn1Wfu mn == 1.675 x 10-27 kg

cillf{~l1Hf+'"l('1iCfl k = 1.381 X 10-23 J K-1

J1ICl'IJIlSilcnl~ NA = 6.022 X 1023 mer"~ cn1~ = 6400 km

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CBSEExaminations.co.cc

A series LCR circuit is connected to an ac source having voltage v = vm sin (Ot.

Derive the expression for the instantaneous current I and its phase relationship to the

applied voltage.

Obtain the condition for resonance to occur. Define 'power factor'. State the

conditions under which it is (i) maximum and (ii) minimum.

'i 14 ifCfi(i fu'3f Cf>T ~ ~ !>lfl1lcml 'I:lffi (~.m.)~ ~ '1&f 'lWlf <.fiT ~ ~ a:uR ~ I W

~ CfiT ~ Frn lIT<m" 31fi:TIfuf ~ I fu'3f cn1 ~ ~ ~ fCf1"fcnffi(1R ~ ~ (llm) CfiT

'qklChll1 $r ~ ~ (~) ~ fcR:r~ !>lfl1ICl('11t~."Q"Cfi. (e.m.f.) ~ itm ~ I ~ ~ ~

~ (1Tm) ~t~."Q"Cfi. (e.m.f.) ~~1iR~m~~ I

~ # LCR (~.m.m.) ~.f<R:it !>lfllIClC11 'I:lffi (~.m.)mo ~ '¥IT ~, ~ ~(~) v = Vm sin rnt, ~ I ~"(11~ ~ 'I:lffi IC'fm -3Fj)l'Piiffi ~ Jffi IcR CWITa:rr ~

~~~m~~~(W{f)~ I

~iR~m~(~)W{f~ 1~-~cR~~ 1~l1R

(i) ~ (ii)~, ~~mq<:ITW<l (~) ~?

30. State Huygens's principle. Show, with the help of a suitable diagram, how thisprinciple is used to obtain the diffraction pattern by a single slit.

Draw a plot of intensity distribution and explain clearly why the secondary maximabecome weaker with increasing order (n) of the secondary maxima. 5

OR

Draw a ray diagram to show the working of a compound microscope. Deduce anexpression for the total magnification when the final image is formed at the nearpoint.

In a compound microscope, an object is placed at a distance of 1.5 em from theobjective of focal length 1.25 em. If the eye piece has a focal length of 5 ern and thefinal image is formed at the near point, estimate the magnifying power of themicroscope.

~ ~ cpt ~ I ~ fu'3f (~) cn1 ~ ~ ~ fCf1"~ ~ <.fiT ~~ fu:RT"[R1 fqqc=R -qur W{f m ~ ~ fct?:rr \$ffiiT ~ I

~~~m~ml11 (~) ~ am~~fCf1" n ~~~W-l rftur3Mt81<Fr~~~irffi~~ I

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fcnm ~ ~~ cn1 CfiPt-fqfu ~ CfiB $ fuir ~ ~ 311W ~ I ~ ~

~f(1f"lk1JiT& $ f.:rcR:~ 1R ~ en ~ ~~ $ "¥f ~ $ fuir ~ ~ (~)~I

oo~~~if~CffiI 1.25 em ~~$-3if~~ 1.5 cm~~~ I~ ~ cn1 ~ ~ 5 em ~ ~ ~ !'lfdf"lk1f.rcR ~ 1R~, en ~~ cn1 ~~W<1~1

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1. A plot of magnetic flux (<1» versus current (I) is shown in the figure for two inductorsA and B. Which of the two has larger value of self inductance? 1

A

B

I~ mcm A 31R B in m1~Chlll lR1Cffi (<1» 31R ~ mu (1) in ~ ~ WLfi (~) m -q~ T]7:IT~ I~ ~ fcR:rtm ~-~ cnr 11T1 ~ ~ ?

B

2. Figure shows three point charges, + 2q, -q and + 3q. Two charges + 2q and - q areenclosed within a surface'S'. What is the electric flux due to this configurationthrough the surface'S' ? 1

+2q.+ 3q.

~Tf<lfu;f-qcfR JWffi, + 2q, - q 3lR + 3q ~Tf<lt I ~ ~ + 2q 31R - q ~~ 'S'-q~t I ~ ~FCl;;qIB inCfiRUTTO 'S' -q~~~~?

+2q•

3. In which orientation, a dipole placed in a uniform electric field is in (i) stable,(ii) unstable equilibrium? 1fcRft~WiR~ $-qW-Rrfu'¥, fcRr ~fCl;;qIf{ -q (1) ~~-q (ii) ~~-q~~?

4. Which part of electromagnetic spectrum is used in radar systems? 1tm c=Br if ~ 1~ChI~~ infcRr WI cnr ~ ~ ~ ?

5. Calculate the speed of light in a medium whose critical angle is 30°. 1fcRft~ in m ~ CfiTur 30° ~, ~ >fCfiTWctiT T:ffiYf fcfm;:ftWIT ?


6. A glass lens of refractive index 1.45 disappears when immersed in a liquid. What isthe value of refractive index of the liquid? 13lqq~'1iCfl 1.45 iFCfiTqiF~~fcR:lT~if~lR% ~m~.g I ~iF 3lqq~'1iCfl CfiT1iR fcFc:Rr.g ?

7. Write the expression for Bohr's radius in hydrogen atom. 1gl~9hH lRlifUJif ~-~ iF m~ ft1furit I

S. A wire of resistance SR is bent in the form of a circle. What IS the effectiveresistance between the ends of a diameter AB ? 1

8R ~ iF ~ OR ~ i'{tiICflI{ ~ m TP-lT.g I ~ am:r AB in;t fun iF ~ ~ ~~Wrr?

9. Explain the function of a repeater in a communication system. 2fcR:ft~ ~ if W:ftz\ (THlq~Cfl) iF C:fiT<t"if)) ~ ~ I

10. (i) Write two characteristics of a material used for making permanent magnets. 2(ii) Why is core of an electromagnet made of ferromagnetic materials?

ORDraw magnetic field lines when a 0) diamagnetic, (ii) paramagnetic substance isplaced in an external magnetic field. Which magnetic property distinguishes thisbehaviour of the field lines due to the two substances?(i) ~~~iFm~~iF;t~~~ I

(i i) ~ ~ CfiT~ ~ ijkl Cf,lll ~ CfiTCf<TIq.:rr men .g ?31mIT

fcRfT~ 1klctl)1l m if w.m- (i) ~f(iijklCfl')"l (ii) 3liijklCfllQ ~ in rn 1klCf,lll ~

00 ~ '"0;t WfiR iF ~ cRm Wr3lTCfiT~ ~ ~ fcR1 ijklCf,I"l 'JUT if ~ inCfiRUT.g ?

11. What is the range of frequencies used in satellite communication? What is commonbetween these waves and light waves? 2~-~ if ~ .:3lF~fT1"l1CfiT llftw ~ ~.g?"0 wrn 31R Wfim"fltrif if CFlT 'EPiHdliWft.g ?

55/1/3 4CBSEExaminations.co.cc

12. A coil Q is connected to low voltage bulb B and placed near another coil P as shownin the figure. Give reasons to explain the following observations:

(a)

(b)

The bulb 'B' lights.

B

Bulb gets dimmer if the coil Q is moved towards left.AC Source

2

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.-----{ I"W )-------,

~Q p

-;;fm fq; m -Jt ~ TJ<IT ~, 1ZCfi ~ Q CfiT ~ (Cflll) ~ cf>~ ~ B ~ ~ TJ<IT ~

31R 1ZCfi ~ ~ P cf>Tffi1 WIT TJ<IT~ I f-i kifC"lf@C1 ~ CfiT~ Cfi8 cf>m CflRUT ~ :

(a) ~B>1cfiRT~(~)~ I

(b) 7:fR:Q ~ CfiTo.wff ~ ~ \iITit ill~ B cf>WPm tit mwrr Cflll m~ ~ I

AC Source.-----{ I"W }-------,

p

13. Find the radius of curvature of the convex surface of a plano-convex lens, whosefocal length is 0.3 m and the refractive index of the material of the lens is 1.5. 2

~~-~~titcrsRIT~~~, ~~~ 0.3 m ~ 31RfsRrctmcnr~qCl~'1iCfi 1.5 ~ I

B

~Q

14. An electron is accelerated through a potential difference of 64 volts. What is thede-Broglie wavelength associated with it ? To which part of the electromagneticspectrum does this value of wavelength correspond? 2

1ZCfi ~ACfGI" CfiT 64 ~ cf> ~ it ~ ~ \iWIT ~ I ~ ~ ~-~ C1~11~t4 fcR:RTirft ? ~ C1{11~t4 CliprR ~ T:PO<SlCf,ll1 ~ cf>fcRT 'lWT c1; Wm~ ?

15. (i) Out of blue and red light which is deviated more by a prism? Give reason.

(ii) Give the formula that can be used to determine refractive index of material of aprism in minimum deviation condition. 2

(i) m q~ trr cf>>1cfiRT1l ~ fcRTCflT, fu;;:l:r cf>~ ~ ~ mw ~ ? CfiRUT~ I

(ii) % ~ ~ ~~, ~ fcrqm w.mr 1l fcR:ft fu;;:l:r cnr ~qCl~'iiCfi ~ <fiB cf>mmWRlT~ I

5 [P.T.O.


16. Plot a graph showing the vanation of stopping potential with the frequency ofincident radiation for two different photosensitive materials having work functionsW J and W 2 (WI> W). On what factors does the (i) slope and (ii) intercept of the

lines depend? 2

-e:T3WfTT-3WfTT ~ Tfiffi WI J:{R W 2 (WI > W 2) * tfilir m~ *m, ~ IClICf}{UI

Cfft ~ *~,f.ffim fcrqq * QRClctPJ cnT~ ~ mcl1 (~) ~ I ~ mcl1 (~) if(i) >fCllJTClT J:{R (i i) 3Rf: m (~;:C:{~ l?:) ~ Cfil\CflT'R f.:r>R ~ ~ ?

17. Draw the circuit diagram of an illuminated photodiode in reverse .bias. How isphotodiodc used to measure light intensity? 2

~ ~ q~+1f<;f~ICflcnTit-sr:frs *m~ 31Tt& ~ I cnTit ~ Cf1T~ Wfirn CfiT

cfrMT ~ if f~:;~nriN\~ ~ ?

18. A heavy nucleus X of mass number 240 and binding energy per nucleon 7.6 MeV issplit into two fragments Y and Z of mass numbers 110 and 130. The binding energyof nucleons in Y and.Z is 8.5 MeV per nucleon. Calculate the energy Q released perfission in MeV. 2

~O'.ll"",H~ 240 -31R 7.6 MeV mfr ~31R ~ ~ Cf1T~'mn~, S;0'14H ~~: 110 ~ 130 * c;J'lWl1 Y J:{R Z if ~ m ~ ~ I Y J:{R Z if~.3iHf qft ~~ 8.5 MeV ~ ~31T;t ~ I mfr ~ dct1~(1 ~ Q *~ Cf1T MeV if qRCfl~H

~I

\\

19. (a) Depict the equipotential surfaces for a system of two identical positive pointcharges placed a distance'd' apart.

(b) Deduce the expression for the potential energy of a system of two point

charges q, and q2 brought from infinity to the points 11 and 12 respectively in~

the presence of external electric field E. 3

(a) ~ ¢ ~'d' ~ 'R w.rc" -e:T'i:Hlilf~(('l~ ~ *,~ ~ * m, ~'l{q ~

cnTm-q~ I

(b) fcr.W <mrr fuwf $ E Cfft ~ if c;J~ ~ ql 4R q2 *~~ Cfft ~

~*m,~~mlOO~ 1~~c;J~,ql kq2cnT,~~~:

11 J:{R 12 ~3iT"(1Cfl ('fT<lPTm ~ I

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20. In a meter bridge, the null point is found at a distance of I) em from A. If now a

resistance of X is connected in parallel with S, the null point occurs at l2 ern. Obtain

a formula for X in terms of i; 12 and S. 3X

r--'VI/Itv--,r II I

s

A~----------L-----------~BjPjijljljljijllijijljljijljljljljijljljipjijliijljijijijijljllljljijllij't

~------~I (~------~~ ~ ~ ~ ~ (~fcr~) ~ A it I) em crft 'IT~ imr%" I~ TtCfi ~ 'X' <:fiT

s it~ (BI1HH) w=r~~fc::<n~ill~fcr~~ 12 em 'IT~itillt I 'X' ct11Rct

fWt TtCfi ~ f'"lCfllfMQ ~ II' '2 31R S ct 11RT it ~ ~ I

X,--"IVVIr--,I rI . I

s•

A~----------L----- ~BIPjli'jlfl(ljlj'lijijijijljljljijljljljii,'j1Plilijil'lljljljijIJljijljil'j

21. What is space wave propagation ? Give two examples of communication systemwhich use space wave mode.A TV tower is 80 m tall. Calculate the maximum distance upto which the signaltransmitted from the tower can be received. 3e<WlrrtrT ~ it cp:rr~ t ? ~ ~ ~ ~3TI cpr 3~1t\{OI tBfurit '%1 ~ ~ cpr~imrtl

~it.cft. (T.V.) iTeR 80 m ~t I~ ~crftcpr qfhflfl'"i ~'%1(lcfl~fu"r.ffIT cnT ~ (~) fcpm \iff ~ t I .

22. (i) Define '~ctivity' of a radioactive material and write its S.I. unit.(ii) Plot a graph showing variation of activity of a given radioactive sample with

time.(iii) The sequence of stepwise decay of a radioactive nucleus is

a ~-D ) D1 ) D2

If the atomic number and mass number of D2 are 71 and 176 respectively, what

are their corresponding values for D ? 3

55/1/3 7 [P.T.O.


(i) fcR:ftm-m~~cit ~fsihllctl cpl~ ~~~.o:m (S.l.) lWICf1~ I

(ii) -w:m ~ ~ 00 fc:.<tTTirm-m ~ LRJ?t~ ~ cit ~fsihllct I -q qf~cH=\'i fu9R ~ m~~(~)~I

(iii) ~m-m~LRJ?tCf)f-;:ftit~TTir ¢tl!o{li~l{ ~~t:ex ~-

D ) Dj ) D2

~ D2 Cf)f'Rl1TUJ-~ (~) ~ ~oq!o{I+~,~: 71 ~ 176 m, rIT D ~ m~ WKr 11RCf<ITmrn ?

23. What is an unpolarized light? Explain with the help of suitable ray diagram how an

unpolarized light can be polarized by reflection from a transparent medium. Write

the expression for Brewster angle in terms of the refractive index of denser medium. 3

~~~Cf<IT~t?~fu;rcit~~~~~fcp~~oo

~ ~ ~ q{lckl'i ~ ~ ~ if ~ t I ~ 1iWfl1 ~ 34qC!~'1iCfi ~ ~ (~) -q~ <RuT ~ m~ fufur<t I

24. Write the principle of working of a potentiometer. Describe briefly, with the help of

a circuit diagram, how a potentiometer is used to determine the internal resistance ofa given cell. 3

~Cf)f~~"CfiT<f-m~ 1~~~cp1~~~~-qquR~

fcp00~ Cf)f311'"f1RCfi~ mrr ~ ctm ~ Cf)f~ ~ -gtn t I

25. Write the expression for the magnetic moment (nO due to a planar square loop of

side'l' carrying a steady current I in a vector form.

In the given figure this loop is placed in a horizontal plane near a long straightconductor carrying a steady current I} at a distance I as shown. Give reasons to

explain that the loop will experience a net force but no torque. Write the expression

for this force acting on the loop. 311

l' )

I

t 0I~

55/1/3 8


00 1 ~ in Wf<W1~ q:l (mT) ~ I 314RC!klo ~ 'tffiT ~ if m ~ I ~

'1klCh"P"l ~ (~) in ~ ~ ~ ~ (~) ~ if ft1furT I

~ rm m if <:Wq:l (mT) 00 ~ ~ ~ in 'lffi ~ I ~ 'R ~ WlffiYfif-nm~ I ~ ~ ~ ~ 31QRC1('11 'tffiT I 1 ~ if m~ I <:W~ Cfl"8 in rn CfiRUT ft1furT fcf ~

q:l (erro) 'R~-2tG'Wf~, fcI:RI~ <I'I<'1It{tli ~~ I q:l (mT) 'RwFt~'Wfinm~ft1furT I

l'I

*It CJ26. A long straight wire of a circular cross-section of radius 'a' carries a steady current

'I'. The current is uniformly distributed across the cross-section. Apply Ampere'scircuital law to calculate the magnetic field at a point 'r' in the region for (i) r < a and(ii)r>a. 3

ORState the underlying principle of working of a moving coil galvanometer. Write tworeasons why a galvanometer can not be used as such to measure current in a givencircuit. Name any two factors on which the current sensitivity of a galvanometerdepends.00 'a' ~11IChI,( ~ ~ in ~ ~ (1R~, 'I' 'i:lRT~ if \iT~ I <:W 'i:lRT(1R in~~if~-wrR~~fcmful~ l~in~R<ll1in~~w~iffcfm~ 'r' 'R '1klCh1<1 ~ cpr 4f{Ch<'1:=( ~, ~ (i) r < am (ii) r > a

armrr• ~o~ 1~'" '''~~ "~1" ~"..:+'"'tl<'1':!isC11 "-11'(1+11'11(r 'iilil2:{) cpr ChI""1ChH.i l'<:1oii.l'\l 1C11'3'-l I II 'i lOll2:'(cpr 1Cf1'<:11~ +i TCfqil

'tffiT 1"f1Frin rn ~ -witrT ~ M "IT ~ I ~ m ~ CfiRUT Afurir I ~ ~ <n CfiRCfl

Afurir fiR 'R fcfm II~'iNI2:{ c€t ~U IU;oIf.:ro/ ~ ~ I

27. A parallel plate capacitor is charged to a potential difference V by a dc source. Thecapacitor is then disconnected from the source. If the distance between the plates isdoubled, state with reason how the following will change;(i) electric field between the plates,(ii) capacitance, and(iii) energy stored in the capacitor. 3~ Bl""JI'"fH W ~ 'Ch1 it.m. (d.c.) ~ mr V ~ (fCfi' ~ fcfm T[7:fT I m~ 'Ch1 ~ ~ ~ CR (-gc:r) ~ T[7:fT I <lR: ~ ~ in itq cR ~ 'Ch1 <n 'JlT CR ~ ;;w:r,'ill Cf)J"'(UT~ Afurir fui, f1 yf(Ylf{g d if cp:rr QRC1~:=( WIT I

(i) ~initqfu"@ ~(ii) ~Cf>l mfun(iii) Wnfur if ~ ~


28. (a) Explain the formation of depletion layer and potential barrier in a p-n junction.

(b) In the figure given below the input waveform is converted into the outputwaveform by a device 'X'. Name the device and draw its circuit diagram.

o ~ Device 'X' lCCC\O\Jj f OutputInput

(c) Identify the logic gate represented by the circuit as shown and write its truthtable. 5

~__:_D-cD---ey

OR

(a) With the help of the circuit diagram explain the working principle of atransistor amplifier as an oscillator.

(b) Distinguish between a conductor, a semiconductor and an insulator on the basisof energy band diagrams.

(a) fcRTI p-n ~ if 0Rft «R ~ ~ fcMcr ct ~ cBTCZ!l&IT~ I

(b ) ~ AA TTirfq;f if f.fcffit 11M ~ em, fcRff ~ 'X' mr f.:1rTc111M ~ if qRClIct \1fcFmTf'lIT ~ I ~ ~ CR ~ ft1furir am ~ ~ ~ ~ I

0:;0c!l ~ 'X' 19CiPmm

(c) m if fu9Tit rr<t ~ ift CR -;:jp::r~ ~ ~ rn {"jC"411 H ~ ~ I

A-----l8----1

p-- ..•y

~

(a) ~ tfficm 31W9 cBT wr:rm ~ fc:f:iffi ~if"1R\ ~ cnT ~ ct ~ if ~ CflB ~

Cfll,,:jchl{l~em~~ I

(b) ~ ~ ~ ct JW:m 1R'~, ~1:lI~CflI ~ fq;q(Hllwrt ~ ~ ~ ~(3RR mfurt) I

29. Describe briefly, with the help of a labelled diagram, the basic elements of an ·A.C.generator. State its underlying principle, Show diagrammatically how an alternatingemf is generated by a loop of wire rotating in a magnetic field. Write the expressionfor the instantaneous value of the emf induced in the rotating loop. 5

OR

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physics cbse 2010 board paper

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