Physics Past Year Paper (Delhi Set -3) - 2014, Class 12, CBSE Class 12 Notes | EduRev

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Class 12 : Physics Past Year Paper (Delhi Set -3) - 2014, Class 12, CBSE Class 12 Notes | EduRev

 Page 1


Series : OSR/I
+dT=i.
Roll No.
--)-i
ilil*". 
55lll3
EdGgRilsrs.{q-yB
.r{si?[sTflari 
r
Candidates must write the Code on
the title page of the answer-book.
o grr-infr'-q q;rii 
flo.gs 
qsr-rrt 
Efffi 
gu 15 t r
o 
trFr-Er 
it qrlri 
aE ftt et{ flqq rq stsqq{ st or* s+r_glwor *Bq_yBq{ furi r
o 
Srr-rn 
dq 
q-r 
.i t*'gq 
q*r-rr 
i[ 
SO ss{ t r
o 
SlrITrFrqT 
vrrfrrrqrvJFqrr++q6*, qT{6,Ts'qi{. 
wEyqfu} r
o 
E{t 
qFT-Et 
*t Td+ + ldq 1S 1qo 
EFr 
{Fl-ir tqqprqr t r 
qw-q{ 
er fuatq 
Wiqq 
ii 
t O. t S 
qi
t*qr 
qr+'n 
I 10.15 
qq 
t 10.30 
qQ 
ro or* *-*e 
qq;r-rr 
si 
qilri 
.fu 
E{i fiqfrr + +{T a
srr-glw+r 
w 
qil$ 
sm roT fui,i r
o 
Please check that this question paper contains 15 printed pages.
o 
Code number given on the right hand side of the question paper should be written on the
title page of the answer-book by the candidate.
o 
Please check that this question paper contains 30 questions.
o 
Please write down the Serial Number of the question before attempting it.
o 
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-book during this period.
snfro,^funmCffins)
PHYSICS (Theory)
fidfril4q :3 €itl 
t 
qrwdq 
aio :70
Timeallowed:3hoursJ 
[MaximumMarks:70
qrqsqfq+sr;
(i) wfiywetffit t
(ii) 
wsnlwtyaso rfl{d' tw t da a-rlsw otfu-algg;f,r}q 
r+qd-ar)rneb-<ra
iiqw* 
r
(iii) 
wr 9 dff d vdqvw 
qt 
aiqw 
*, 
yw 
tg d zz t sdqsfr dfr oi€w 
iaEr 
yw
2s d so 
if 
sAqs?a ftq iiqw 
t r
(iv) dTr d*t dtd wif C d 
qer1€ 
wqtfTdm * I
(v) n,rurr 
il 
wqt 
q-{. 
6H fu zat * I dEtfu, 
ql 
ei6t 
qtd 
W 
wr 
4 
dTpiof ard 
W
vwif sidr?fu 
ffi*Idd?if-wif t etrafuqwyq+fuqTTqrt 
/ 
dder+ t eilwl
frdqd 
qwf 
t d*Td 
g'oyFrf 
*rar* t
5511t3 
I 
1p.T.O.
Page 2


Series : OSR/I
+dT=i.
Roll No.
--)-i
ilil*". 
55lll3
EdGgRilsrs.{q-yB
.r{si?[sTflari 
r
Candidates must write the Code on
the title page of the answer-book.
o grr-infr'-q q;rii 
flo.gs 
qsr-rrt 
Efffi 
gu 15 t r
o 
trFr-Er 
it qrlri 
aE ftt et{ flqq rq stsqq{ st or* s+r_glwor *Bq_yBq{ furi r
o 
Srr-rn 
dq 
q-r 
.i t*'gq 
q*r-rr 
i[ 
SO ss{ t r
o 
SlrITrFrqT 
vrrfrrrqrvJFqrr++q6*, qT{6,Ts'qi{. 
wEyqfu} r
o 
E{t 
qFT-Et 
*t Td+ + ldq 1S 1qo 
EFr 
{Fl-ir tqqprqr t r 
qw-q{ 
er fuatq 
Wiqq 
ii 
t O. t S 
qi
t*qr 
qr+'n 
I 10.15 
qq 
t 10.30 
qQ 
ro or* *-*e 
qq;r-rr 
si 
qilri 
.fu 
E{i fiqfrr + +{T a
srr-glw+r 
w 
qil$ 
sm roT fui,i r
o 
Please check that this question paper contains 15 printed pages.
o 
Code number given on the right hand side of the question paper should be written on the
title page of the answer-book by the candidate.
o 
Please check that this question paper contains 30 questions.
o 
Please write down the Serial Number of the question before attempting it.
o 
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-book during this period.
snfro,^funmCffins)
PHYSICS (Theory)
fidfril4q :3 €itl 
t 
qrwdq 
aio :70
Timeallowed:3hoursJ 
[MaximumMarks:70
qrqsqfq+sr;
(i) wfiywetffit t
(ii) 
wsnlwtyaso rfl{d' tw t da a-rlsw otfu-algg;f,r}q 
r+qd-ar)rneb-<ra
iiqw* 
r
(iii) 
wr 9 dff d vdqvw 
qt 
aiqw 
*, 
yw 
tg d zz t sdqsfr dfr oi€w 
iaEr 
yw
2s d so 
if 
sAqs?a ftq iiqw 
t r
(iv) dTr d*t dtd wif C d 
qer1€ 
wqtfTdm * I
(v) n,rurr 
il 
wqt 
q-{. 
6H fu zat * I dEtfu, 
ql 
ei6t 
qtd 
W 
wr 
4 
dTpiof ard 
W
vwif sidr?fu 
ffi*Idd?if-wif t etrafuqwyq+fuqTTqrt 
/ 
dder+ t eilwl
frdqd 
qwf 
t d*Td 
g'oyFrf 
*rar* t
5511t3 
I 
1p.T.O.
(vi) #d$der# vqqh a7 oryp 16? * r dqrfu 
qF 
erwqq 
al dl eflq 
@q 
svot w
qqir6rn.6-4f, 
r
(vii) 
qai 
ernvqq 
al 
enq 
ffiafuil 
,tfuT 
fuqdiq;t n 
qr+t 
w sqqlq ar s+-d f ,
c:3 x 108 m/s
h: 6.63 x 10-34 Js
e: 1.6 x 10-19 C
Po:4nx 
l0*7TmA-l
1
-;-:9 
x 109 Nm2 C-2
+Trto
m.:9'1 x 10-31 kg
General Instructions :
(i) All questions are compulsory.
(ii) There are 30 questions in total. 
Question 
Nos. I to I are very short answer type
questions ond caruy one mark each.
(iii) 
Question 
Nos. 9 to 18 carry two mqrl{s each. 
Question 
Nos. 19 to 27 carry three
marks each and question nos. 28 to 30 carryJive marks each.
(iv) One of the questions carrying three marks weightage is value based question.
(v) There is no overall choice. However, an internal choice has been provided in one
question of two marks, one question of three marlrs and all three questions ofJive
marl{s each weightage. You have to attempt only one of the choices in such
questions.
(vt) Use of calculators is not permitted. However, you may use log tables if necessary.
(vii) You may use the 
following 
values of physical constants wherever necessary :
c:3 x 108 m/s
h: 6.63 x 10-34 Js
e: 1.6 x 10-19 C
Vr:4nx 
10-7TmA-l
I
-: 
9 x lge Nm2 C-2
4neo
m.:9'1 x 10-31 kg
55nt3 2
Page 3


Series : OSR/I
+dT=i.
Roll No.
--)-i
ilil*". 
55lll3
EdGgRilsrs.{q-yB
.r{si?[sTflari 
r
Candidates must write the Code on
the title page of the answer-book.
o grr-infr'-q q;rii 
flo.gs 
qsr-rrt 
Efffi 
gu 15 t r
o 
trFr-Er 
it qrlri 
aE ftt et{ flqq rq stsqq{ st or* s+r_glwor *Bq_yBq{ furi r
o 
Srr-rn 
dq 
q-r 
.i t*'gq 
q*r-rr 
i[ 
SO ss{ t r
o 
SlrITrFrqT 
vrrfrrrqrvJFqrr++q6*, qT{6,Ts'qi{. 
wEyqfu} r
o 
E{t 
qFT-Et 
*t Td+ + ldq 1S 1qo 
EFr 
{Fl-ir tqqprqr t r 
qw-q{ 
er fuatq 
Wiqq 
ii 
t O. t S 
qi
t*qr 
qr+'n 
I 10.15 
qq 
t 10.30 
qQ 
ro or* *-*e 
qq;r-rr 
si 
qilri 
.fu 
E{i fiqfrr + +{T a
srr-glw+r 
w 
qil$ 
sm roT fui,i r
o 
Please check that this question paper contains 15 printed pages.
o 
Code number given on the right hand side of the question paper should be written on the
title page of the answer-book by the candidate.
o 
Please check that this question paper contains 30 questions.
o 
Please write down the Serial Number of the question before attempting it.
o 
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-book during this period.
snfro,^funmCffins)
PHYSICS (Theory)
fidfril4q :3 €itl 
t 
qrwdq 
aio :70
Timeallowed:3hoursJ 
[MaximumMarks:70
qrqsqfq+sr;
(i) wfiywetffit t
(ii) 
wsnlwtyaso rfl{d' tw t da a-rlsw otfu-algg;f,r}q 
r+qd-ar)rneb-<ra
iiqw* 
r
(iii) 
wr 9 dff d vdqvw 
qt 
aiqw 
*, 
yw 
tg d zz t sdqsfr dfr oi€w 
iaEr 
yw
2s d so 
if 
sAqs?a ftq iiqw 
t r
(iv) dTr d*t dtd wif C d 
qer1€ 
wqtfTdm * I
(v) n,rurr 
il 
wqt 
q-{. 
6H fu zat * I dEtfu, 
ql 
ei6t 
qtd 
W 
wr 
4 
dTpiof ard 
W
vwif sidr?fu 
ffi*Idd?if-wif t etrafuqwyq+fuqTTqrt 
/ 
dder+ t eilwl
frdqd 
qwf 
t d*Td 
g'oyFrf 
*rar* t
5511t3 
I 
1p.T.O.
(vi) #d$der# vqqh a7 oryp 16? * r dqrfu 
qF 
erwqq 
al dl eflq 
@q 
svot w
qqir6rn.6-4f, 
r
(vii) 
qai 
ernvqq 
al 
enq 
ffiafuil 
,tfuT 
fuqdiq;t n 
qr+t 
w sqqlq ar s+-d f ,
c:3 x 108 m/s
h: 6.63 x 10-34 Js
e: 1.6 x 10-19 C
Po:4nx 
l0*7TmA-l
1
-;-:9 
x 109 Nm2 C-2
+Trto
m.:9'1 x 10-31 kg
General Instructions :
(i) All questions are compulsory.
(ii) There are 30 questions in total. 
Question 
Nos. I to I are very short answer type
questions ond caruy one mark each.
(iii) 
Question 
Nos. 9 to 18 carry two mqrl{s each. 
Question 
Nos. 19 to 27 carry three
marks each and question nos. 28 to 30 carryJive marks each.
(iv) One of the questions carrying three marks weightage is value based question.
(v) There is no overall choice. However, an internal choice has been provided in one
question of two marks, one question of three marlrs and all three questions ofJive
marl{s each weightage. You have to attempt only one of the choices in such
questions.
(vt) Use of calculators is not permitted. However, you may use log tables if necessary.
(vii) You may use the 
following 
values of physical constants wherever necessary :
c:3 x 108 m/s
h: 6.63 x 10-34 Js
e: 1.6 x 10-19 C
Vr:4nx 
10-7TmA-l
I
-: 
9 x lge Nm2 C-2
4neo
m.:9'1 x 10-31 kg
55nt3 2
1.
2.
ffi 
qreroit 
sTrivr 
q6dt 
t 
qq{ren'r 
+1qfo{qr frfuq $kqremt rdrkd 
qrr 
t w*
+iaiq sr Bdq eifqq r
Define the term 'drift velocity' of charge carriers in a conductor and write its
relationship with the current flowing through it.
ffi t*o- +1qm-+.n{rr *} 
qs 
lltrrafffi foqr 
rrqr 
t :
C(t) 
: 
3 sin (8 nt) volt
1.5
m(t) Et€if
qrSET 
ilirr 
qfliq 
ergvn+tte,i 
ilr'r t I frgtr{ qf,sim.f,m +ifqq r
The carrier wave of a signal is given by C(t) 
: 
3 sin (8zrt) volt. The modulating signal
is a square wave as shown. Find its modulation index.
1.5
m(t) in volt
t in second
gqdq 
qh 
B fr +'r V t 
rrfuqrr 
ffi 
sTra{r * onur dt€-s 
3e-"iq 
qn 
F *fuq 
qiwr 
6q
tf 
aq*t* | 
ys gq*iq 
qh 
*t flqvn Hr t z
Write the expression, in a vector form, for the Lorentz magnetic force F due to a
charge moving with velocity V in a magnetic field B. Wfrut is the direction of the
magnetic force ?
qqr{ 
caAs +frq 
qRr 
orY{*€dr 
*.+q fr-trtur *t 
qfli+ 
*.fuq 
qrq.dfuq 
t
Plot a graph showing variation of current versus voltage for the material GaAs.
5. ffi ct-o ?t( si ffi 
qq-o-e q{"r 
+ {qS 
it 
ror 
rrqr 
t r 
e$ 
{i*${ *. ere{ 
w {qiq-{ t
20 cm$ w furd ffi fl+5tsf, fuq 
qr qfrkEq 
sfr 
fuq +ffi t r its 6t st-ns qt frr
tr I
A convex lens is placed in contact with a plane mirror. A point object at a distance of
20 cm on the axis of this combination has its image coinciding with itself. What is the
focal length of the lens ?
J.
4.
55/U3
lP.T.O.
Page 4


Series : OSR/I
+dT=i.
Roll No.
--)-i
ilil*". 
55lll3
EdGgRilsrs.{q-yB
.r{si?[sTflari 
r
Candidates must write the Code on
the title page of the answer-book.
o grr-infr'-q q;rii 
flo.gs 
qsr-rrt 
Efffi 
gu 15 t r
o 
trFr-Er 
it qrlri 
aE ftt et{ flqq rq stsqq{ st or* s+r_glwor *Bq_yBq{ furi r
o 
Srr-rn 
dq 
q-r 
.i t*'gq 
q*r-rr 
i[ 
SO ss{ t r
o 
SlrITrFrqT 
vrrfrrrqrvJFqrr++q6*, qT{6,Ts'qi{. 
wEyqfu} r
o 
E{t 
qFT-Et 
*t Td+ + ldq 1S 1qo 
EFr 
{Fl-ir tqqprqr t r 
qw-q{ 
er fuatq 
Wiqq 
ii 
t O. t S 
qi
t*qr 
qr+'n 
I 10.15 
qq 
t 10.30 
qQ 
ro or* *-*e 
qq;r-rr 
si 
qilri 
.fu 
E{i fiqfrr + +{T a
srr-glw+r 
w 
qil$ 
sm roT fui,i r
o 
Please check that this question paper contains 15 printed pages.
o 
Code number given on the right hand side of the question paper should be written on the
title page of the answer-book by the candidate.
o 
Please check that this question paper contains 30 questions.
o 
Please write down the Serial Number of the question before attempting it.
o 
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-book during this period.
snfro,^funmCffins)
PHYSICS (Theory)
fidfril4q :3 €itl 
t 
qrwdq 
aio :70
Timeallowed:3hoursJ 
[MaximumMarks:70
qrqsqfq+sr;
(i) wfiywetffit t
(ii) 
wsnlwtyaso rfl{d' tw t da a-rlsw otfu-algg;f,r}q 
r+qd-ar)rneb-<ra
iiqw* 
r
(iii) 
wr 9 dff d vdqvw 
qt 
aiqw 
*, 
yw 
tg d zz t sdqsfr dfr oi€w 
iaEr 
yw
2s d so 
if 
sAqs?a ftq iiqw 
t r
(iv) dTr d*t dtd wif C d 
qer1€ 
wqtfTdm * I
(v) n,rurr 
il 
wqt 
q-{. 
6H fu zat * I dEtfu, 
ql 
ei6t 
qtd 
W 
wr 
4 
dTpiof ard 
W
vwif sidr?fu 
ffi*Idd?if-wif t etrafuqwyq+fuqTTqrt 
/ 
dder+ t eilwl
frdqd 
qwf 
t d*Td 
g'oyFrf 
*rar* t
5511t3 
I 
1p.T.O.
(vi) #d$der# vqqh a7 oryp 16? * r dqrfu 
qF 
erwqq 
al dl eflq 
@q 
svot w
qqir6rn.6-4f, 
r
(vii) 
qai 
ernvqq 
al 
enq 
ffiafuil 
,tfuT 
fuqdiq;t n 
qr+t 
w sqqlq ar s+-d f ,
c:3 x 108 m/s
h: 6.63 x 10-34 Js
e: 1.6 x 10-19 C
Po:4nx 
l0*7TmA-l
1
-;-:9 
x 109 Nm2 C-2
+Trto
m.:9'1 x 10-31 kg
General Instructions :
(i) All questions are compulsory.
(ii) There are 30 questions in total. 
Question 
Nos. I to I are very short answer type
questions ond caruy one mark each.
(iii) 
Question 
Nos. 9 to 18 carry two mqrl{s each. 
Question 
Nos. 19 to 27 carry three
marks each and question nos. 28 to 30 carryJive marks each.
(iv) One of the questions carrying three marks weightage is value based question.
(v) There is no overall choice. However, an internal choice has been provided in one
question of two marks, one question of three marlrs and all three questions ofJive
marl{s each weightage. You have to attempt only one of the choices in such
questions.
(vt) Use of calculators is not permitted. However, you may use log tables if necessary.
(vii) You may use the 
following 
values of physical constants wherever necessary :
c:3 x 108 m/s
h: 6.63 x 10-34 Js
e: 1.6 x 10-19 C
Vr:4nx 
10-7TmA-l
I
-: 
9 x lge Nm2 C-2
4neo
m.:9'1 x 10-31 kg
55nt3 2
1.
2.
ffi 
qreroit 
sTrivr 
q6dt 
t 
qq{ren'r 
+1qfo{qr frfuq $kqremt rdrkd 
qrr 
t w*
+iaiq sr Bdq eifqq r
Define the term 'drift velocity' of charge carriers in a conductor and write its
relationship with the current flowing through it.
ffi t*o- +1qm-+.n{rr *} 
qs 
lltrrafffi foqr 
rrqr 
t :
C(t) 
: 
3 sin (8 nt) volt
1.5
m(t) Et€if
qrSET 
ilirr 
qfliq 
ergvn+tte,i 
ilr'r t I frgtr{ qf,sim.f,m +ifqq r
The carrier wave of a signal is given by C(t) 
: 
3 sin (8zrt) volt. The modulating signal
is a square wave as shown. Find its modulation index.
1.5
m(t) in volt
t in second
gqdq 
qh 
B fr +'r V t 
rrfuqrr 
ffi 
sTra{r * onur dt€-s 
3e-"iq 
qn 
F *fuq 
qiwr 
6q
tf 
aq*t* | 
ys gq*iq 
qh 
*t flqvn Hr t z
Write the expression, in a vector form, for the Lorentz magnetic force F due to a
charge moving with velocity V in a magnetic field B. Wfrut is the direction of the
magnetic force ?
qqr{ 
caAs +frq 
qRr 
orY{*€dr 
*.+q fr-trtur *t 
qfli+ 
*.fuq 
qrq.dfuq 
t
Plot a graph showing variation of current versus voltage for the material GaAs.
5. ffi ct-o ?t( si ffi 
qq-o-e q{"r 
+ {qS 
it 
ror 
rrqr 
t r 
e$ 
{i*${ *. ere{ 
w {qiq-{ t
20 cm$ w furd ffi fl+5tsf, fuq 
qr qfrkEq 
sfr 
fuq +ffi t r its 6t st-ns qt frr
tr I
A convex lens is placed in contact with a plane mirror. A point object at a distance of
20 cm on the axis of this combination has its image coinciding with itself. What is the
focal length of the lens ?
J.
4.
55/U3
lP.T.O.
6. ++ ffi 
qrr+.{tqrqcnqT 
sr ffiE sTi{q t{qr.rqr t rx' ERT ilqih.fr orErirq + reqrlqq
qY{{ssr q.r{ 
frfuq I
qffirqtd
frN, ru,* frmo*
The figure given below shows the block diagram of a generalized communication
system. Identifu the element labelled 'X' and write its function.
I
lnformation
Source
i-rrgug,:Er---- 
-R3c-e1vgr--l
Message
Signal
Message
Signal
7. HITH {rrg +Ei 
rfd-6; 
Mt 
\1*. 
qq 
sr f,en 
ESn 
*iq HT 
t Um 
Fq t sqn 
ffit 
T.fi
qr 
tnrq 
q-i 
t r 
r+i 
t 
q+-{ qrrt('r$ rntr 
T{ T€,d 
qgtm 
et{ Fii r
Two spherical bobs, one metallic and the other of glass, of the same size are allowed
to fall freely from the same height above the ground. Which of the two would reach
earlier and why ?
..m 
,fr 
oTrn{r kqrs +'frq, ffi tq-€ t 
.fw1i E{l-(,rT, 
TrqBqq 
yB f{qd 
qiT 
+
E]_dr t r" 
g{ 
6e6 *t glqsifqq ,
"For any charge configuration, equipotential surface through a point is normal to the
electric field." Justify.
1 cm cqr{"+ffi Aqd fr-{q of we ffi 
q+.sqn 
frqil 
q+-{ ii qq q-sr{rerr qrff 
t, frW
cil s{qr 
t* t oo' 
q.1 
6iur 
omrq, 
ir-tr {6 tdqq orF N* * eo 
qq"t q.r 
sr$re o-rcn t r 
qk
tat{d 
qr 
sTra{r + 
2 nC 
t 
Hi 
Wftt furfuq Eqt 
qfit*fud 
+ilqq r
An electric dipole of length I with its axis making an angle of 60o
8.
9.
An electric dipole of length I cm, which placed with its axis making an angle of 60o
with uniform electric field, experiences a torque of 6\F Nm. Calculate the potential
energy of the dipole if it has charge 
+ 
2 nC.
55llt3 4
wqhT-
m..df
Page 5


Series : OSR/I
+dT=i.
Roll No.
--)-i
ilil*". 
55lll3
EdGgRilsrs.{q-yB
.r{si?[sTflari 
r
Candidates must write the Code on
the title page of the answer-book.
o grr-infr'-q q;rii 
flo.gs 
qsr-rrt 
Efffi 
gu 15 t r
o 
trFr-Er 
it qrlri 
aE ftt et{ flqq rq stsqq{ st or* s+r_glwor *Bq_yBq{ furi r
o 
Srr-rn 
dq 
q-r 
.i t*'gq 
q*r-rr 
i[ 
SO ss{ t r
o 
SlrITrFrqT 
vrrfrrrqrvJFqrr++q6*, qT{6,Ts'qi{. 
wEyqfu} r
o 
E{t 
qFT-Et 
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o 
Please check that this question paper contains 15 printed pages.
o 
Code number given on the right hand side of the question paper should be written on the
title page of the answer-book by the candidate.
o 
Please check that this question paper contains 30 questions.
o 
Please write down the Serial Number of the question before attempting it.
o 
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-book during this period.
snfro,^funmCffins)
PHYSICS (Theory)
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c:3 x 108 m/s
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e: 1.6 x 10-19 C
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l0*7TmA-l
1
-;-:9 
x 109 Nm2 C-2
+Trto
m.:9'1 x 10-31 kg
General Instructions :
(i) All questions are compulsory.
(ii) There are 30 questions in total. 
Question 
Nos. I to I are very short answer type
questions ond caruy one mark each.
(iii) 
Question 
Nos. 9 to 18 carry two mqrl{s each. 
Question 
Nos. 19 to 27 carry three
marks each and question nos. 28 to 30 carryJive marks each.
(iv) One of the questions carrying three marks weightage is value based question.
(v) There is no overall choice. However, an internal choice has been provided in one
question of two marks, one question of three marlrs and all three questions ofJive
marl{s each weightage. You have to attempt only one of the choices in such
questions.
(vt) Use of calculators is not permitted. However, you may use log tables if necessary.
(vii) You may use the 
following 
values of physical constants wherever necessary :
c:3 x 108 m/s
h: 6.63 x 10-34 Js
e: 1.6 x 10-19 C
Vr:4nx 
10-7TmA-l
I
-: 
9 x lge Nm2 C-2
4neo
m.:9'1 x 10-31 kg
55nt3 2
1.
2.
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Define the term 'drift velocity' of charge carriers in a conductor and write its
relationship with the current flowing through it.
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t :
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: 
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The carrier wave of a signal is given by C(t) 
: 
3 sin (8zrt) volt. The modulating signal
is a square wave as shown. Find its modulation index.
1.5
m(t) in volt
t in second
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Write the expression, in a vector form, for the Lorentz magnetic force F due to a
charge moving with velocity V in a magnetic field B. Wfrut is the direction of the
magnetic force ?
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Plot a graph showing variation of current versus voltage for the material GaAs.
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tr I
A convex lens is placed in contact with a plane mirror. A point object at a distance of
20 cm on the axis of this combination has its image coinciding with itself. What is the
focal length of the lens ?
J.
4.
55/U3
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The figure given below shows the block diagram of a generalized communication
system. Identifu the element labelled 'X' and write its function.
I
lnformation
Source
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Signal
Message
Signal
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Two spherical bobs, one metallic and the other of glass, of the same size are allowed
to fall freely from the same height above the ground. Which of the two would reach
earlier and why ?
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"For any charge configuration, equipotential surface through a point is normal to the
electric field." Justify.
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An electric dipole of length I with its axis making an angle of 60o
8.
9.
An electric dipole of length I cm, which placed with its axis making an angle of 60o
with uniform electric field, experiences a torque of 6\F Nm. Calculate the potential
energy of the dipole if it has charge 
+ 
2 nC.
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State the underlying principle of a cyclotron. Write briefly how this machine is used to
accelerate charged particles to high energies.
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A capacitor'C', a variable resistor 'R' and a bulb 'B' are connected in series to the ac
mains in circuit as shown. The bulb glows with some brightness. How will the glow of
the bulb change if (i) a dielectric slab is introduced between the plates of the capacitor,
keeping resistance R to be the same; (ii) the resistance R is increased keeping the same
capacitance ?
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A dbuteron and an alpha particle are accelerated with the same accelerating potential.
Which one of the two has
(1) greater value of de-Broglie wavelength, associated with it and
(2) less kinetic energy ? Explain.
13. 
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Out of the two magnetic materials, 'A' has relative permeability slightly greater than
unity while 'B' has less than unity. Identify the nature of the materials 'A' and 'B'.
Will their susceptibilities be positive or negative ?
55lll3
lP.T.O.
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