Past Year Paper, Physics (Set - 2), Delhi, 2014, Class 12, Physics Class 12 Notes | EduRev

 Page 1


Series : OSR/I
stsi.
Code No.
sslll2
dni..
Roll No.
3f,{-5rwfir s.{q-YB
q{ qqrq 
fut} r
Candidates must write the Code on
the title page of the answer-book.
o 
!ffirqiqo,-{i} 
toqs vrt-rl,t { 
Eidf, 
gs 15 t r
o HFr-rr fr 
qriEi 
6rE ftt 
ertriqq 
rrq 
Ets'rqr *i 6H cr{-5fitrs, *.{e-Y*qrled r
o gtl-{ drq 
qr 
.i fl*.gs 
qFt-rt it 
so 
qF 
t r
o 
StrrlTtrFtq.T 
3-f,{frq.{rEsur*rt 
q6d, qrt 
ot xqiq' wqfqfntl t
. 
EqqFT-Er 
dr r6i +fuq ts fu+aifl {rqzr fqqT 
rrqr 
t r 
qn-.rd 
or fuawrWRq 
i[ 
to.ts 
qi
flsqr 
qr+qT 
I 10.15 
qq 
t 10.30 
qi 
ro or* *-q-e 
qFt-wt 
fti 
qi,t 
efu qs erqtl + ftH A
e+r-gfir*r 
qr 
*t$ wt reT fui) t
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.
$)ftro,flildm 
C*'€TFffi)
PHYSICS 
(TheorY)
fuiffudtr : 3 
Eitl t 
srfqadq eiq :70
Time allowed: 3 hours 
I 
I 
Maximum Marlcs : 70
wqrqfr*vr:
(i) wrlmwetW* r
(ii) 
Wsq7wif 
yaSO rffif tynr l da r+- ivw 
qfd-dyt\q 
ff?d'*pqd6-fr
aiqwt r
(iii) 
yntg 
dra # slqsfl Et 
ai€w*, sw tg d zr 
if 
vdqwq aTqiiqw*aqrvw
2s I so i s46v?q frq 
eiqw 
* t
(iv) dhffiqtde{iff d<'ofs 
eiltttftaswt r
(v) w7w 
if 
aqrt rr *H fu +d * I dqtfu, d ffi arLd 
Wwt 
il, 
dh 
tiqit ad 
V6
yw 
t 
ofu {tq 
oi6f 
qld 
dH 
ywf t'J s17afuaqq 
yqrq 
fuqr TqT t / 
dC 
aw} 
it zltwl
I?d 
q+ qrif it 
d #ftr 
wwr 
a7 51q { 1
55nt2 
I IP'T'O'
Page 2


Series : OSR/I
stsi.
Code No.
sslll2
dni..
Roll No.
3f,{-5rwfir s.{q-YB
q{ qqrq 
fut} r
Candidates must write the Code on
the title page of the answer-book.
o 
!ffirqiqo,-{i} 
toqs vrt-rl,t { 
Eidf, 
gs 15 t r
o HFr-rr fr 
qriEi 
6rE ftt 
ertriqq 
rrq 
Ets'rqr *i 6H cr{-5fitrs, *.{e-Y*qrled r
o gtl-{ drq 
qr 
.i fl*.gs 
qFt-rt it 
so 
qF 
t r
o 
StrrlTtrFtq.T 
3-f,{frq.{rEsur*rt 
q6d, qrt 
ot xqiq' wqfqfntl t
. 
EqqFT-Er 
dr r6i +fuq ts fu+aifl {rqzr fqqT 
rrqr 
t r 
qn-.rd 
or fuawrWRq 
i[ 
to.ts 
qi
flsqr 
qr+qT 
I 10.15 
qq 
t 10.30 
qi 
ro or* *-q-e 
qFt-wt 
fti 
qi,t 
efu qs erqtl + ftH A
e+r-gfir*r 
qr 
*t$ wt reT fui) t
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.
$)ftro,flildm 
C*'€TFffi)
PHYSICS 
(TheorY)
fuiffudtr : 3 
Eitl t 
srfqadq eiq :70
Time allowed: 3 hours 
I 
I 
Maximum Marlcs : 70
wqrqfr*vr:
(i) wrlmwetW* r
(ii) 
Wsq7wif 
yaSO rffif tynr l da r+- ivw 
qfd-dyt\q 
ff?d'*pqd6-fr
aiqwt r
(iii) 
yntg 
dra # slqsfl Et 
ai€w*, sw tg d zr 
if 
vdqwq aTqiiqw*aqrvw
2s I so i s46v?q frq 
eiqw 
* t
(iv) dhffiqtde{iff d<'ofs 
eiltttftaswt r
(v) w7w 
if 
aqrt rr *H fu +d * I dqtfu, d ffi arLd 
Wwt 
il, 
dh 
tiqit ad 
V6
yw 
t 
ofu {tq 
oi6f 
qld 
dH 
ywf t'J s17afuaqq 
yqrq 
fuqr TqT t / 
dC 
aw} 
it zltwl
I?d 
q+ qrif it 
d #ftr 
wwr 
a7 51q { 1
55nt2 
I IP'T'O'
(vl *a-fdzr- * dqqhT *7 eAqA ?E? * r aqrfr 
qfr 
emtqq 
al al 
enq dgqaffi?q wrwft w
sqhrwrrqrdd- r
(vii) 
qrt 
oilqyqtdl 
wq ffifud 
q)futfrqdiqif 
nqni w aqqlr 
qE 
nm-d f,,
c:3x108m/s
h:6.63 x 10Ja Js
e: 1.6 x 10-19 C
Fo:4xx 
l0-7TmA-l
1
G:9 
x loe Nm2 c-2
m.:9'1 x 10-31 kg
Generul Instructions :
(i) All questions are compulsory.
(ii) There are 30 questions in total. 
Question 
Nos. I to I are very short answer type
questions and caruy one mark each.
(iiil 
Question 
Nos. 9 to 18 carry two marks each. 
Question 
Nos. 19 to 27 carry three
marl<s each and question nos. 28 to 30 carryJive marl<s 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 nuo morlcs, one question of three marlrs and all three questions oflive
marks each weightage. You have to attempt only one of the choices in such
questions.
(vil Use of calculators is not permitted. However, you may use log tables if necessary.
(viil You may use the 
following 
yalues 
of plrysical constants wherever necessory :
c:3x108m/s
h:6.63 x 10-34 Js
e: 1.6 x 10-19 C
Vr:4xx 
10-7TmA-l
I
-;-:9 
x 109 Nm2 C-2
+fieo
m":9'1 x 10-31 kg
55nt2 2
Page 3


Series : OSR/I
stsi.
Code No.
sslll2
dni..
Roll No.
3f,{-5rwfir s.{q-YB
q{ qqrq 
fut} r
Candidates must write the Code on
the title page of the answer-book.
o 
!ffirqiqo,-{i} 
toqs vrt-rl,t { 
Eidf, 
gs 15 t r
o HFr-rr fr 
qriEi 
6rE ftt 
ertriqq 
rrq 
Ets'rqr *i 6H cr{-5fitrs, *.{e-Y*qrled r
o gtl-{ drq 
qr 
.i fl*.gs 
qFt-rt it 
so 
qF 
t r
o 
StrrlTtrFtq.T 
3-f,{frq.{rEsur*rt 
q6d, qrt 
ot xqiq' wqfqfntl t
. 
EqqFT-Er 
dr r6i +fuq ts fu+aifl {rqzr fqqT 
rrqr 
t r 
qn-.rd 
or fuawrWRq 
i[ 
to.ts 
qi
flsqr 
qr+qT 
I 10.15 
qq 
t 10.30 
qi 
ro or* *-q-e 
qFt-wt 
fti 
qi,t 
efu qs erqtl + ftH A
e+r-gfir*r 
qr 
*t$ wt reT fui) t
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.
$)ftro,flildm 
C*'€TFffi)
PHYSICS 
(TheorY)
fuiffudtr : 3 
Eitl t 
srfqadq eiq :70
Time allowed: 3 hours 
I 
I 
Maximum Marlcs : 70
wqrqfr*vr:
(i) wrlmwetW* r
(ii) 
Wsq7wif 
yaSO rffif tynr l da r+- ivw 
qfd-dyt\q 
ff?d'*pqd6-fr
aiqwt r
(iii) 
yntg 
dra # slqsfl Et 
ai€w*, sw tg d zr 
if 
vdqwq aTqiiqw*aqrvw
2s I so i s46v?q frq 
eiqw 
* t
(iv) dhffiqtde{iff d<'ofs 
eiltttftaswt r
(v) w7w 
if 
aqrt rr *H fu +d * I dqtfu, d ffi arLd 
Wwt 
il, 
dh 
tiqit ad 
V6
yw 
t 
ofu {tq 
oi6f 
qld 
dH 
ywf t'J s17afuaqq 
yqrq 
fuqr TqT t / 
dC 
aw} 
it zltwl
I?d 
q+ qrif it 
d #ftr 
wwr 
a7 51q { 1
55nt2 
I IP'T'O'
(vl *a-fdzr- * dqqhT *7 eAqA ?E? * r aqrfr 
qfr 
emtqq 
al al 
enq dgqaffi?q wrwft w
sqhrwrrqrdd- r
(vii) 
qrt 
oilqyqtdl 
wq ffifud 
q)futfrqdiqif 
nqni w aqqlr 
qE 
nm-d f,,
c:3x108m/s
h:6.63 x 10Ja Js
e: 1.6 x 10-19 C
Fo:4xx 
l0-7TmA-l
1
G:9 
x loe Nm2 c-2
m.:9'1 x 10-31 kg
Generul Instructions :
(i) All questions are compulsory.
(ii) There are 30 questions in total. 
Question 
Nos. I to I are very short answer type
questions and caruy one mark each.
(iiil 
Question 
Nos. 9 to 18 carry two marks each. 
Question 
Nos. 19 to 27 carry three
marl<s each and question nos. 28 to 30 carryJive marl<s 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 nuo morlcs, one question of three marlrs and all three questions oflive
marks each weightage. You have to attempt only one of the choices in such
questions.
(vil Use of calculators is not permitted. However, you may use log tables if necessary.
(viil You may use the 
following 
yalues 
of plrysical constants wherever necessory :
c:3x108m/s
h:6.63 x 10-34 Js
e: 1.6 x 10-19 C
Vr:4xx 
10-7TmA-l
I
-;-:9 
x 109 Nm2 C-2
+fieo
m":9'1 x 10-31 kg
55nt2 2
2.
t. ffi 
qeo+i 
t{d 
qk'rs-dr 
s1qfrqm *rsr*.r s.r. 
qrr*.frfug 
r
Define the term 'electrical conductivity' of a metallic wire. Write its S.L unit.
ffi 
qrdril{q 
6ffiO 
*t 
gq 
u-+nftrsfqd flq.qr 
,rqr 
t :
C(t): 5 sin(lOzrt) volt
st$ 
qr$ffi 
forqi{ 
qvriq q-{qr q,t 
ili.r t r 
qrge=T 
qErsis.rlf, +iflqq r
2
m(t) 
Etris{
tt-+-sif
The carrier wave is represented by
C(t): 5 sin(l0nt) volt
A modulating signal is a square wave as shown. Determine modulation index.
2
m(t) in volt
t in second
qrs if 
nrq * 
qrpT 
si *1qftrtr{silr *r kqtur 
qflf{q 
r
Show variation of resistivity of Si with temperature in a graph.
ffi urrt Ftq *i ffi wrae 
qqrr 
+ {FrrS 
ii 
ror 
rrqr 
t r 
gq 
{*sH * 
e+q 
q{ 
{qlq{ t
20 cm$ w fiprd ffi 
ffisn 
kq *l 
yfrkq 
{S 
fqq +{qrfi t r iis +i sls'q 
$ 
wt
tz
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 ?
5. "flm-s $ 
eTr+{r 
fuqrs +fdq, ffi k{t.Jq{i 
q-6, qqfrr1q 
ggfu{d 
q+d 
+ 
qFrf,Es{d
Etdr t r" 
w 
ser{ *1gfudfqq r
"For any charge configuration, equipotential surface through a point is normal to the
electric field." Justifu.
a
J.
4.
55ll12
lP.T.O.
Page 4


Series : OSR/I
stsi.
Code No.
sslll2
dni..
Roll No.
3f,{-5rwfir s.{q-YB
q{ qqrq 
fut} r
Candidates must write the Code on
the title page of the answer-book.
o 
!ffirqiqo,-{i} 
toqs vrt-rl,t { 
Eidf, 
gs 15 t r
o HFr-rr fr 
qriEi 
6rE ftt 
ertriqq 
rrq 
Ets'rqr *i 6H cr{-5fitrs, *.{e-Y*qrled r
o gtl-{ drq 
qr 
.i fl*.gs 
qFt-rt it 
so 
qF 
t r
o 
StrrlTtrFtq.T 
3-f,{frq.{rEsur*rt 
q6d, qrt 
ot xqiq' wqfqfntl t
. 
EqqFT-Er 
dr r6i +fuq ts fu+aifl {rqzr fqqT 
rrqr 
t r 
qn-.rd 
or fuawrWRq 
i[ 
to.ts 
qi
flsqr 
qr+qT 
I 10.15 
qq 
t 10.30 
qi 
ro or* *-q-e 
qFt-wt 
fti 
qi,t 
efu qs erqtl + ftH A
e+r-gfir*r 
qr 
*t$ wt reT fui) t
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.
$)ftro,flildm 
C*'€TFffi)
PHYSICS 
(TheorY)
fuiffudtr : 3 
Eitl t 
srfqadq eiq :70
Time allowed: 3 hours 
I 
I 
Maximum Marlcs : 70
wqrqfr*vr:
(i) wrlmwetW* r
(ii) 
Wsq7wif 
yaSO rffif tynr l da r+- ivw 
qfd-dyt\q 
ff?d'*pqd6-fr
aiqwt r
(iii) 
yntg 
dra # slqsfl Et 
ai€w*, sw tg d zr 
if 
vdqwq aTqiiqw*aqrvw
2s I so i s46v?q frq 
eiqw 
* t
(iv) dhffiqtde{iff d<'ofs 
eiltttftaswt r
(v) w7w 
if 
aqrt rr *H fu +d * I dqtfu, d ffi arLd 
Wwt 
il, 
dh 
tiqit ad 
V6
yw 
t 
ofu {tq 
oi6f 
qld 
dH 
ywf t'J s17afuaqq 
yqrq 
fuqr TqT t / 
dC 
aw} 
it zltwl
I?d 
q+ qrif it 
d #ftr 
wwr 
a7 51q { 1
55nt2 
I IP'T'O'
(vl *a-fdzr- * dqqhT *7 eAqA ?E? * r aqrfr 
qfr 
emtqq 
al al 
enq dgqaffi?q wrwft w
sqhrwrrqrdd- r
(vii) 
qrt 
oilqyqtdl 
wq ffifud 
q)futfrqdiqif 
nqni w aqqlr 
qE 
nm-d f,,
c:3x108m/s
h:6.63 x 10Ja Js
e: 1.6 x 10-19 C
Fo:4xx 
l0-7TmA-l
1
G:9 
x loe Nm2 c-2
m.:9'1 x 10-31 kg
Generul Instructions :
(i) All questions are compulsory.
(ii) There are 30 questions in total. 
Question 
Nos. I to I are very short answer type
questions and caruy one mark each.
(iiil 
Question 
Nos. 9 to 18 carry two marks each. 
Question 
Nos. 19 to 27 carry three
marl<s each and question nos. 28 to 30 carryJive marl<s 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 nuo morlcs, one question of three marlrs and all three questions oflive
marks each weightage. You have to attempt only one of the choices in such
questions.
(vil Use of calculators is not permitted. However, you may use log tables if necessary.
(viil You may use the 
following 
yalues 
of plrysical constants wherever necessory :
c:3x108m/s
h:6.63 x 10-34 Js
e: 1.6 x 10-19 C
Vr:4xx 
10-7TmA-l
I
-;-:9 
x 109 Nm2 C-2
+fieo
m":9'1 x 10-31 kg
55nt2 2
2.
t. ffi 
qeo+i 
t{d 
qk'rs-dr 
s1qfrqm *rsr*.r s.r. 
qrr*.frfug 
r
Define the term 'electrical conductivity' of a metallic wire. Write its S.L unit.
ffi 
qrdril{q 
6ffiO 
*t 
gq 
u-+nftrsfqd flq.qr 
,rqr 
t :
C(t): 5 sin(lOzrt) volt
st$ 
qr$ffi 
forqi{ 
qvriq q-{qr q,t 
ili.r t r 
qrge=T 
qErsis.rlf, +iflqq r
2
m(t) 
Etris{
tt-+-sif
The carrier wave is represented by
C(t): 5 sin(l0nt) volt
A modulating signal is a square wave as shown. Determine modulation index.
2
m(t) in volt
t in second
qrs if 
nrq * 
qrpT 
si *1qftrtr{silr *r kqtur 
qflf{q 
r
Show variation of resistivity of Si with temperature in a graph.
ffi urrt Ftq *i ffi wrae 
qqrr 
+ {FrrS 
ii 
ror 
rrqr 
t r 
gq 
{*sH * 
e+q 
q{ 
{qlq{ t
20 cm$ w fiprd ffi 
ffisn 
kq *l 
yfrkq 
{S 
fqq +{qrfi t r iis +i sls'q 
$ 
wt
tz
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 ?
5. "flm-s $ 
eTr+{r 
fuqrs +fdq, ffi k{t.Jq{i 
q-6, qqfrr1q 
ggfu{d 
q+d 
+ 
qFrf,Es{d
Etdr t r" 
w 
ser{ *1gfudfqq r
"For any charge configuration, equipotential surface through a point is normal to the
electric field." Justifu.
a
J.
4.
55ll12
lP.T.O.
6. ge-drq 
eir B t +'r V t 
rrioqn 
ffi sil-n{r * +nur Filt{-q gqslq 
qe 
F *- fleq Hiqvr Fq
{ 
t*qofmfuq 
r 
vq 
gls+iq 
qld 
dr krn wr t z
Write the expression, in a vector form, for the Lorentz magnetic force F due to a
charge moving with velocity ? in a magnetic field B. Wfrut is the direction of the
magnetic force ?
+n ffi 
qrq+. 
{iqrc 
qc[€rT 
sr Ri-s 3iliq 
frqr 
rrqr 
t | 'x' ERI rrqikd orcrftt 6t 
.rnqrfrq
eftrg*r*r 
sd frfuq
t- 
- - - - - - - - -l
rl
I
!l-JI
r1fir 
qln
frf'*
The figure given below shows the block diagram of a generalized communication
system. Identi$ the element labelled'X' and write its function.
t- 
- - - - - - -l
1l
7.
Message
Signal
Message
Signal
9.
stTFT Tr{q + d 
rilirqr, 
ffit 
q*. qrq 
6T ?rn 
Es{r 
oiq or t, 
Em 
Fq t sqsa ffit 
E-rtr
q{ 
fl,rnq 
q-i 
t r 
q+i 
t 
qt-{ 
Hr 
rtr€rs qrfr qr.rcd qg+n 
ek Bit 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 thr ground. Which of the two would reach
earlier and why ?
qfltq q-{sr 
ffi 
qfrw{ if 
ac tq * 
qr*l 
d"hfiq 
it 
1furirr 'C', sfiffi 
qftRltr* 
'R' defl 6t$
GrGr 
'B' {qikd t r 
qw 
EE 
qrs'*'qrrr qf,dr 
t r 
qk 
(i) 
qftR}r-+. 
B 6} 
qqsq 
w6T,
{qriu ft1 
qifsrcit 
+ +q st* 
qtr+qil qfr*r 
rq fi 
qK, 
(ii) 
qrRdT 
*t vqrq rcrrr 
qftrdtrs'n
tl qf;r 
w 
qt qrq, 
d *q +t 
qq-oil q1 qfiffi 
tt'n z
frn*o"
55fit2
Page 5


Series : OSR/I
stsi.
Code No.
sslll2
dni..
Roll No.
3f,{-5rwfir s.{q-YB
q{ qqrq 
fut} r
Candidates must write the Code on
the title page of the answer-book.
o 
!ffirqiqo,-{i} 
toqs vrt-rl,t { 
Eidf, 
gs 15 t r
o HFr-rr fr 
qriEi 
6rE ftt 
ertriqq 
rrq 
Ets'rqr *i 6H cr{-5fitrs, *.{e-Y*qrled r
o gtl-{ drq 
qr 
.i fl*.gs 
qFt-rt it 
so 
qF 
t r
o 
StrrlTtrFtq.T 
3-f,{frq.{rEsur*rt 
q6d, qrt 
ot xqiq' wqfqfntl t
. 
EqqFT-Er 
dr r6i +fuq ts fu+aifl {rqzr fqqT 
rrqr 
t r 
qn-.rd 
or fuawrWRq 
i[ 
to.ts 
qi
flsqr 
qr+qT 
I 10.15 
qq 
t 10.30 
qi 
ro or* *-q-e 
qFt-wt 
fti 
qi,t 
efu qs erqtl + ftH A
e+r-gfir*r 
qr 
*t$ wt reT fui) t
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.
$)ftro,flildm 
C*'€TFffi)
PHYSICS 
(TheorY)
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Time allowed: 3 hours 
I 
I 
Maximum Marlcs : 70
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c:3x108m/s
h:6.63 x 10Ja Js
e: 1.6 x 10-19 C
Fo:4xx 
l0-7TmA-l
1
G:9 
x loe Nm2 c-2
m.:9'1 x 10-31 kg
Generul Instructions :
(i) All questions are compulsory.
(ii) There are 30 questions in total. 
Question 
Nos. I to I are very short answer type
questions and caruy one mark each.
(iiil 
Question 
Nos. 9 to 18 carry two marks each. 
Question 
Nos. 19 to 27 carry three
marl<s each and question nos. 28 to 30 carryJive marl<s 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 nuo morlcs, one question of three marlrs and all three questions oflive
marks each weightage. You have to attempt only one of the choices in such
questions.
(vil Use of calculators is not permitted. However, you may use log tables if necessary.
(viil You may use the 
following 
yalues 
of plrysical constants wherever necessory :
c:3x108m/s
h:6.63 x 10-34 Js
e: 1.6 x 10-19 C
Vr:4xx 
10-7TmA-l
I
-;-:9 
x 109 Nm2 C-2
+fieo
m":9'1 x 10-31 kg
55nt2 2
2.
t. ffi 
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Define the term 'electrical conductivity' of a metallic wire. Write its S.L unit.
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t :
C(t): 5 sin(lOzrt) volt
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The carrier wave is represented by
C(t): 5 sin(l0nt) volt
A modulating signal is a square wave as shown. Determine modulation index.
2
m(t) in volt
t in second
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Show variation of resistivity of Si with temperature in a graph.
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A convex lens is placed in contact with a plane mirror. A point object at a distance of
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focal length of the lens ?
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electric field." Justifu.
a
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4.
55ll12
lP.T.O.
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Write the expression, in a vector form, for the Lorentz magnetic force F due to a
charge moving with velocity ? in a magnetic field B. Wfrut is the direction of the
magnetic force ?
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The figure given below shows the block diagram of a generalized communication
system. Identi$ the element labelled'X' and write its function.
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Message
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 thr ground. Which of the two would reach
earlier and why ?
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10.
A capacitor'C', a variable resistor 
oR' 
and a bulb 
oB' 
are connected in series to the ac
mains in circuit as shown. The bulb glows widh 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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An electric dipole of length 2 cm, when placed with its axis making an angle of 60o
with a uniform electric field, experiences a torque of 81[ Nm. Calculate the potential
energy of the dipole, if it has a charge of 
+ 
4 nC.
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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 ?
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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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t{t + faq }. H{'rM + ffi 
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monochromatic light of wavelength
2
first minimum of the interference paffern of a
1
l, occurs at an angle of 
;. 
At the same angle of
?,,
;, 
*. get a maximum for two narrow slits separated by a distance "a". Explain.
55lll2 5
lP.T.O.