2008 Physics Question Paper

7/29/2019 2008 Physics Question Paper

1/15

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I S ri s SOS I C de N . 55/1

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Roll No. I I I I I I I I Candidates must write the Code on~ ~. I I I I I I I I the til page of the answr-book.

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. Please check that this question paper contains 15 printed pages.. Cde number gien on the riht hand sie of the questin paper shoul 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 beforeattempting it.

. 15 miutes time has been altte d to read thi questin paper. The questinpaper will be distributed at 10.15 a.m. From 10.15 a.m. to 10.30 a.m., thestudents will read the question paper only and will not write any answeron the answer script during this period.

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PHYSICS (Theory)mf(!J"i fa~R (~ ~ I ~ Q) )

Time alw d.. 3 hours Maximum Marks.. 70

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55/1 1 P.T.D.c--

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Downloaded From: http://www.cbseportal.com



2/15

.

(v) Use of calculators is not permitted. However, you may use logtabtcti if nt'Ct'33ary.

(vi Y u may use the fol wg val es of phy i l constants w erev r

necessary :

c = 3 x 108 m/s

h = 6.q3 x 10-34 Js

e = 1.6 x 10-19 C

Jl = 47t x 10-7 T m AI

1

- = 9 x 109 N m2 C 2

47tE

0

me = 9.1 x 10-31 kg

H4fI-


3/15

( v ~ " "< 1j . f 2 r i i ~ q ; J- 3 1 :J 1 lr r ~ . # I r r ;J T fr r ; ! 1f G r 3 11 q ' : t I ! . ! c t > f i a T 3 : rT V

I!.! "f1T1:uft q;r m -q:;( ~ i I

(vi) ~ 3 11 q' :t I! .! c> f i 3 1J q" R or fI ," i i l ] ;f f w ~ - q: ;( ~i! :

c = 3 x 108 m/sh = 6.63 x 10-34 Js

'"':'1 e = 1.6 x 10-19 C

~o = 47t x 10-7 T m AI

1

9 2 2- = 9 x 10 N m C0

me = 9.1 x 10-31 kg

1 . Dfi e e l cr i d i o l mo me n t. W ie i s S l u n i . 1

~ ~~ ~ ~ ~ ~ I ~ ~.31r;f


4/15

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6. Tw bar magnets are qui kl moved tow rds a metal l op connected

across a capacitor 'c' as shown in the figure. Predict the polarity of the. 'capacItor. 1C

Is IN sl N-+ -E--

m - q: ~ ~ ~ G T ~ ' fl i bT C 11 , ~ ~ ~ ~ ~ ( ~) ~ 3 ff i ~

~ ~ ~ ~ ~ , -'3fT ~ ~ 'C ~ ~~ (T) ~ I ~~ ~ ~ "qj

~ ~~II~~ IC

Is IN sl N

-+ -E--

7. What happens to the width of depletion layer of a p-n junction when itis (i) forward biased, (ii) reverse biased? 1

~ p-n ~ ~ ~ lR('f ~ ~ (~) 'q"{ ~ ~ ~ ~, ~ p-n ~

(i) 31~I~~lctI ~1~1~11 m, (i 1.I~-qI~~lctI ~1~1~11 m ?

8. Define the term 'stopping potential' in relation to photoelectric effect. 1~ - ~ ~ ~ ~ if 'RUm fq'1:rq' -q?,: ~ ~ ~ I

9 . A t h i s t ra i h t i f i i e l l n g c o nd uc t i g w e h av i g c a r g e d en s i y

A i enc sed by a cyl dri al surface of radi s r and l ngth l i s axi

coinciding with the length of the wire. Find the expression for theelectric flux through the surface of the cylinder. 2~ r ~ ~ l ~ ~ ~~o1lct1l( (~) -q:, A ~ ~ ~ ~ ~"qjT ~ ~, mm ~ dR ~ ~ I ~~o1l t1l ~ ~ ~, dR ~ ~ ~~ ~ I ~~o1lct1l( ~ ~ ~ ~ ~ ~ ~ ~ ~ I

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5/15

Pt a graph sow g the variti n of coulmb force (F) versus" ( -4),w ere r i the di tance betw en the tw charges of eac pal of

carges: (1 ~C 2 ~C and (2 ~C - 3 ~C. Interpret the graphs

obtained. 231fcm ~ ~ ~, (1 ~C 2 ~C ~ (2 ~C -3 ~C ~ ~ ~ ~ (F) q)"T

(~ ) ~ ~ -q~ ~ ~ ~ 31ri ri l ( mtfi ) ~ I 'G1"o1T m ~ -q ~ 31fc m

~ ~ ~ ~ r ~ I '5rT"({:r".{~ ft) ~ cX Il 1 ~ IWie the expresin for Lorentz magneti force on a parti of

charge 'q' moving with velocity "1 i a magneti fi l B S ow thatno w rk i done by thi force on the charged parti l. " 2

OR

A steady current (11) fl w through a l ng strai ht w e. A other w e

carryi g steady c rrent (12) i the same d iecti n i k pt cl se and

paral l to the fi s w e. S ow w h the hel of a di gram how the

magneti fi l d ue to the current 11 exerts a magneti forc on the

second we. Wie the exresi n for thi force. 2

B ~~ ~ -q "1 ~ ~ l fu ~ ~ 'q' ~ ~ fC im qjU ~.. wH ~ ~

~~~~~~~ I ~~fCi~~31T~"qjU~

~q;r4~~~~1

3t~

~ ~ mi ~ ~ ~ ~ ~ 'i :rTU (11) ~ m "{tft ~ I ~ "('fR ~ ~

~ ~ ~I-II~~, ~ a:r;


6/15

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13. What is sky wave communication? Wh:):' is this mode of propagationrestricted to the frequencies only upto few MHz?

6. ~-m ~ ~ ~ ~ ~ ? ~ ~ ~ ~ ~ MH ~ ~~ "(fq)" m

~~mm~ ?

1 4. I n t h e g i e n c i c ui , a ss u mi g p o i t A t o b e a t z e ro p ot e nt i l u s e

K chhoff 's rul s to determi e the potenti l at poi t B

2V

l D 2 II B

R 2 .Q R

A II C 2A

IV

~~~i, ~~~~~A:I"{~~~, ~~~~~~

~I ~ B 1:1"{ ~ ~ ~ I

2V

1 II B

R 1

,i

I I iA C 2A 1

IV i

i

15. A paral l pl te capacior i bei g c arged by a time v ry g current.!

E pl i bri fl how Ampere's c cui al l w i general ed to:

incorporate the effect due to the displacement current. !~ ~j..jl~~ ~ ~~ -ri ~ ~ ~ ~ ~ ~ 3:jmrn ~ ~ W ~ I)~ i ~ ~ ~ ~ ~ ~ q=j\U ~ ~"q:j ~j..jI~~I'i ~ ~ ~'I~ "5[qiR ~ ~ ~Ft~"(.jl~ "q:jT ~I~~I~~UI M ";jffiT ~ I

55/1 6

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7/15

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of three identical capacitors in series is 1 J.1F.Whattheir net capacitance if connected n parallel?

the rati of energy stored i the tw confiuratins i they are

cnnected to the same source. 2

(-q:q;-~) ~~ ~ ~ i ~~ ~ (~) ~ ~ ~ (~)

1 J.1F ~ I ~ ~ -q~ (~ ~) i ~~ M (~) ~, m ~

~ mlt ?

l (~~) i ~~ ~ -q:q; m ~ ~ ~ ~, m ~ ~ ~ ~

e for the binding energy per nucleon as a function ofumber A state c l arl how the rel ase i energy i theof nuclear fission and nuclear fusion can be explained. 2

~ A ~ ~ ~ ~ i , ~ ~3fR -at~ ~ c:nT ~ ~ ~ ~

~ , ~~ fqm ~ ~~ ~ ~ i ~ fq1J;m ~ ~ -c:IT@i

~~ I

the meter brige exeriment, balnce poit ws observed at J wh

= .e v al e s o f R a nd X w r e d ou bl d a nd t he n i t er ch an ge d. W at

would be the new position of balance point?If the galvanometer and battery are interchanged at the balanceposition, how will the balance point get affected? 2

R X

1A B

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8/15

~ ~ (~) ~ ~ m ~, ~~ ~ ( ~ ~) J -q"{ ~~, ~ A = l(i R ~ X ~ ~ qj ~ - q:j { ~ 3T r:fff ~ ~ ~ ~, m ~~ ~

~;r{~~m1fi?

(ii) * 31ff.f~~ >!T1:{f ~ -q"{ ~i~r1IJ-1Ic.{ ~ ~ ~ ~ 3Tr:fff ~ ~~~m 31~~-q"{~~~?

1

19. A convex lens made up of glass of refractive index 1.5 is dipped, inturn, in (i) a medium' of refractive index 1.65, (ii) a medium ofrefractive index 1.33.(a) W i behave as a convergi g or a di ergi g l ns i the tw

cases?

(b) H w w i s focal l ngth change i the tw medi ? 3

~~q\:fr1i~ 1.5 ~ ~ ~ ~ ~ ~ qj) ~ (i) 1.65 31~q\:fr1i~ ~,(i 1.33. 31~q\:fr1i ~ ~ ~ ~ ~ I

(a) ~ GT ~3# ~ ~ ~ ~ ~ ~ m q:j.f ~ ~ ~ ~ ~

11Tfu?

(b) ~ GT ~ ~ ~ ~ ~ ~ ~ ~ ~ -qftq-


9/15

-~

~".J "c'"Draw a plot showing the variation of photoelectric current withcol cor pl te potenti l for tw di ferent frequenci s, v > v ' of

i ci ent radi ti n ha vi g t he s ame i tensi y. I n w i h c s w t he c l

stoppi g potenti l be hi her? Justi y your answ r. 3 ~

~ ~ am vI ~ v ~ (V > v2) t GT 31fqfu"ff ~~~ul t ~, ~

~ ( ~) f cf qq t m ?: I' , ~ -~ ~ t - q~ - q; ) ~ t ~ m lf i ( ~)

~ I ~ G m ~ R Ut ft f cf qq " q: j ~ a m ~ ? ~ ' 3" W t ~ ~ ~ " qj RU

(~)~ I

W ie br if l any t w f ac tor s w i h dem onst rat e t he need f or

modulating a signal.Draw a suitable diagram to show amplitude modulation using asinusoidal signal as the modulating signal. 3

~ ~ (fuT;rC) -q;) ~ oq;1 31lq~~~dl ~ mm ~, ~ ~ t ~ ~ ~~ GT "CiRq:; ( ~ ) ~ I

3W:fTr:r ~ -q;) ~ t ~ ~ ~ ~ ~, ~ ~lq~l~ fuT;rC1 "q:jT~ ~ fuT;rC oq;1 ~ ~ ~ m I

U e the mi ror equati n to show that

(a) an obj ct pl ced betw en f and 2f of a concave mi ror produc s a

real image beyond 2f.(b) a convex mi ror alw ys produces a vi tual image i dependent of

the location of the object.(c) an object placed between the pole and focus of a oncave mirror

produces a virtual and enlarged image. 3~ ~1i~~U "q:j ~ ~ ~ ~ ~

(a) ~ ~ t f am 2f t ~ ~ ~ "q:j ~, 2f ~ 31rTt (oq't;) am

qll ~ mm ~ I

(b) ~ ~ ~ a:rrrrrm }fl~~ ~ ~, ~ ~ ~ C:ft m I

(c ~ ~ ~ ~ am ~ ~ ~ ~ ~ "q:j }frn~~ a:rrrrrm am 31~

. mm~1

P.T.D.




10/15

'--'-.~ ~-~" --,.} --~ ;'.'-cc'

23. Draw a labelled diagram of a full wave rectifier circuit. State itsworking principle. Show the input-output waveforms. 3~ Ct1T R 'qft"q?;r '"q:j ~ -i~i tJd 31lW ~ I ~'ctJl~ctJl\1 ~~ I mm 3ffi ~ W T-~ ~ ~ I

24. (a) Using de Broglie's hypothesis, explain with the help ofa suitablediagram, Bohr's second postulate of quantization of energy levelsin a hydrogen atom.

(b) The ground state energy of hydrogen atom i -13.6 eV Wat are

the ki eti and potenti l energi s of the el ctron i thi state? 3

(a) ~ ~ ~ YRtJ~"11 ~ ~ ~, ~~ ~ .q: ~ ~ ~ ~I~~

~~ ~ ~ ~ ~~ ~, ~ 31lW (m) ~ ~QI(.j l ~ ~

~I

(b) ~~~ ~ ~ l i d~ ~ ~ - 13.6 eV m"ffi ~ I ~ ~ .q:

~~~~3ffi~~m"ffi ?

25. Yu are gien a cicui belw Wie is truth tabl. Hnce, ientiy

the l gi operati n carri d out by thi ci cui . D aw the l gi s mbol of

the gate it corresponds to. 3

A

Z

B

~ ~ ~ 'qft"q?;r ~ ~ ~~~i1 ~ ~ I ~ ~ ~~ m ~ ~ 'qRi~ "S"~ (~an)~ ~ ~ I ~ Wmit-CI;"q:jT~ ~ I

A X

Z .

B Y

55/1 10




11/15

A compound mi oscope us s an obj cti e l ns of focal l ngth 4 cm and

eye pi c l ns of f oca l l ngt h 10 c m. A obj ct i pl ced at 6 c m f rom

the objctie lns. Cl ulte the magniyig powr of the cmpound

microscope. Also calculate the length of the microscope. 3

OR

A g i n t r e fr ac t i g t e l s c pe a t a n o bs e rv a to r y h as a n o bj c t i l n s o f

focal l ngth 15 m. If an eyepi ce l ns of focal l ngth 1.0 cm i used, fi d

the angular magnification of the telescope.If this telescope is used to view the moon, what is the diameter of the

image of the moon formed by the objctie lns? The dimeter of the

m o on i 3 . 42 x 1 06 m a nd t h e r ad i s o f t h e l n a r o r bi i 3 . 8 x 1 0 8 m . 3

~ ~ ~Gm ~ -3=1fi ~ ~ am ~ ~ CI1 ~ ?j '!i ~ 4 cm

am 10 cm ~ I ~ ~ q)) 3=li~ ~ ~ 6 cm ~ ~ -;:;m:rT ~ I ~ ~

~Gm CI1 31fq~ ~ am ~ ~ 1ft ~ ~ I

3T~

~ ~~ i ~ ~ -quqffi ~~ ~ 3tM~ ~ C I1 ~ ~ 15 m

~ I ~ ~ 1 .0 c m ~ ~ C I1 ~ ~ "q )T ~ ~ ~ , " i ~ ~ ~

"Ci~~~~?

~ ~ ~qj ~ ~ q)) ~ ~, "i ~ ~~ ~ ~ ~ ~ ~

} j t~~ "CfiT ~ ~ ? ~ "CfiT 3.42 106m~ am~ CfI1C I1 ~ 3.8 x 108 m ~ I

P.T.D.

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12/15

L --- I -.- :::=~.. _o~~,I.,:

27. Tw heati g el ments of res anc s R and R w en operated at a

constant suppl of v lage, V c ns me pow rs P and P res ect i l .

Deduce the expressions for the power of their combination when theyare, in turn, connected in (i) series and (ii) parallel across the samevoltage supply. 3

R~ R~ ~ ~ ~~, ~ (~) q1 " F2"" (' ! T V ~ ~m

~ ~~ ~ -q"{, ~ P am P m ~ ~ tr I ~ ~ ~ ~ m

~ ~ ( i ~ ~ - i ~ ( i - q~ ( ~) - i ~ ~ ~ ( ~) ~ , m

~ ~~ (mal - i ~ m ~ ~ ~ ~ ~ I

28. (a) State the principle of the working of a moving coil galvanometer,giving its labelled diagram.

(b) "Increasing the current sensitivity of a galvanometer may notnecessarily increase its voltage sensitivity." Justify this statement.

(c) Outline the necessary steps to convert a galvanometer of resistanceRG i t o an ammeter o f a g i n range . 5

OR

(a) U i g A mpere's ci cui al l w obt~i the expressi n for the

magnetic field due to a long solenoid at a point inside the solenoid ion its axis. !

(b) In w at res ect i a toroi di fer ent fr om a sol noi ? D aw and j

c ompare t he pa t t e rn o f t he magne t i f i l l es i t he tw c as s

(c) H w i the magneti fi l i si e a gi en sol noi made s rong? 5

(a) ~ ~ ~ (~~-1I~Ic.~) ~ -q"{ ~ ~ ~, ~ am~ ~ -11~il~d ~ ~ I

(b) "fCfim jl~-1I~Ic.~~ 'i:Tm-~mfu"ffi ~ -q"{ ~ ~-~~ qjT '1ft~ ~IC\~~~ ~ ~ I" ~ -q:;~ ~ ~ -ij ~ (-q:;r{UT) ~ I

55/1 12

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13/15

(c) R m'i1 ~ fCim ~i o1lI~~ -qj fCim ~ ~ (~) -qftm ~ ~ i

4FtctFf1d ~ ~ 3:jlct~(.j~ -qj) ~ I

3T~(a) ~ ~ 4Ft4~1(.j ~ ~ ~, ~ ~ 4Fto1lr~~1 ~ ~, ~ ~~ fCfim~ "Q\, ~~~ ~ ~ ~, ~ ~ "SrTt(f ~ I(b) fCfim 4Fto1lr~~1 ~ ~ ~ ~ "5fq)T{ fi:r;r ~ ~ ? ~ ~ ~ ~~~ ~ ~an "Cf)Tq"2-;f ~ ~ ~ ~ I(c) fCfim~ ~ 4Fto1lr~~1~ ~ ~~ ~ -qj) ~ ~ ~ :;jfffiT~ ?

.State the working of a.c. generator with the help of a labelleddiagram.

The coi of an a.c. generator havi g N turns, each o f area A i

rotated wh a constant angulr velciy roo Dduce the expresin for

the alternating e.m.f. generated in the coil.What is the source of energy generation in this device? 5 ~tic

OR 'i "

~f;'

(a) S ow that i an a.c. ci cui contai i g a pure i ductor, the ~:!k~~.voltage is ahead of current by n/2 in phase. ':

(b) A hori ntal strai ht w e of l ngth L extendi g from east to w s

is falling with speed v at right angles to the horizontal componentof E rth's magneti fi l B

(i) Write the expression for the instantaneous value of thee.m.f. induced in the wire.

(ii) What is the direction of the e.m.f. ?(iii) Which end of the wire is at the higher potential? 5

13 P T .0.

c""" -"




14/15

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~ ril~il~('[ 31ftJ!1 -q;1 ~~It.j 11 ~ quR ~ fC i "' ;I;~Ic\(11 Y "m:r (a.c.) ~ ~ ~~~I

M "5r~Ic\(11 Y "m:r ~ -q;1 ffi i f N ~ ~ I ~ -qj ~ A ~ I ffi

~~~~I-1 ~ ~ (j ~ ~ ~ W ~ I ~ ffi i f ~ )'!~Ic\(11 ~~

~({.~.~.)~~~~~~ I

~ ~ if ~ ~~I~~ -qj ~ ~ ~ ?

3T~

(a) ~ ~ fC i ~ ~ ~ M ~~Ic\(1i Y "m:r (a.c.) "qftq'l i f, ~

~ (~) i f ~ Y " m: r ~ n /2 a :n i ~ ~ I

(b) ~ L -qj, ~ ~ mm "Cm:, ~ "-~ ~ ~ 31~ ~, T['l;.ft ~

~~~B ~~~~v ~~f i R~ I

(i ~"Cm: i f ~ ~-~ ~ ({.~.~.) ~ "('[~fi rqj -qR ~ ~

~~I I(i ~ ~~~ ~ ({.~.~.) -q;1 ~ ~ mrTr ?

(i ~"ffi{ ~ ~ ~ ~ fqoqq ~ ~ ~ ~ (~) ~ ?

30. State the importance of coherent sources in the phenomenon ofinterference.In Young's double slit experiment to produce interference pattern,obtain the conditions for constructive and destructive interference.Hence deduce the expression for the fringe width.H w d oe s th e f ri ge w t h g et a ff ect ed , i t he e nt ie e xpe rim en ta lapparatus of Young is immersed in water? 5

OR

(a) S ate H ygens' pri ci l . U i g thi pri ci l expl i how a

diffraction pattern is obtained on a screen due to a narrow slit onw i a narrow beam comi g from a monochromati source o f

light is incident normally.(b) Show that the angular width of the first diffraction fringe is halfof that of the central fringe.(c) If a monochromatic source of light is replaced by white light,what change would you observe in the diffraction pattern? 5

55!1 14 55

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15/15

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11 ~ "qjfim m "qj ~ ~ ~, ~ I

m ~ d.jldctl~UI ~ "5{T(('r ~ ~ ~, ~ ~ ~ d.jldctl~UI,' r ~ 3 W ~ ~ ~ ~ ~ ~ ~ ~ ( "5 {T (( 'r ) ~ I

~ m ~ ~ ~\.fctlU ~ m ~ ~ ~ ~, m ~ ~ ~ ~

31~

"qj fu";&Rr ~ ~ , ~ I ~ fu";&Rr ~ ~ ~ ~ ~ ~

~ fCim ~ (~) ~ (~) "q"'{, fCim ~qouff ~ ~ ~ ~

~ ~ mU t'31, ~~ ~~, m ~"q"'{ ~ ~ ~

~ ~ "S"~ ~ ~ ~ ~ ~, ~ ~ ~ ~

~ ~ (1/2) mm ~ I

1

~qouff ~ ~ ~ ~ "q"'{ m ~ ~ m ~, m fqq-d;r ~

~ ~ -qftq'

2008 Physics Question Paper

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