JEE Main 2020 Physics January 8 Shift 1 Paper & Solutions | Mock Tests for JEE Main and Advanced 2025 PDF Download

 Page 1


     
 
      
    
     
     
 
                       
 
  
PAGE # 1 
 
 
PART : PHYSICS 
 
Single Choice Type   (,dy fodYih; izdkj) 
This section contains 20 Single choice questions. Each question has 4 choices (1), (2), (3) and (4) for its 
answer, out of which Only One is correct. 
bl [k.M esa 20 ,dy fodYih iz'u gSaA izR;sd iz'u ds 4 fodYi (1), (2), (3) rFkk (4) gSa] ftuesa ls flQZ ,d lgh gSA 
 
1. A block of mass m is connected at one end of spring fixed at other end having natural length ?0 and 
spring constant K. The block is rotated with constant angular speed ( ?) about the fixed end in gravity 
free space. The elongation in spring is–  
 ,d CykWd ftldk nzO;eku m gS dks izkdfrd yEckbZ ?0 rFkk cy fu;rkad K  dh fLizax ds ,d fljs ls tqM+k gqvk gS 
rFkk fLizax dk nwljk fljk tM+or~ gSA CykWd dks tM+or fljs ds ifjr% xq:Roghu LFkku esa fu;r dksf.k; pky ( ?) ls 
?kqek;k tkrk gS rks fLizax es f[kpko crkb, 
 (1) 
2
2
0
m k
m
? ?
? ?
    (2) 
2
2
0
m k
m
? ?
? ?
    (3) 
? ?
?
m k
m
2
0
?
    (4) 
? ?
?
m k
m
2
0
?
   
Ans. (1) 
Sol.  
? ? k, ?0
m
 
m ?
2 
( ?0 + x) = kx 
 
2
0
m
k
1
x ?
? ?
?
?
?
?
?
?
?
 
 x = 
2
2
0
m k
m
? ?
? ?
  
 
2. 3 point charges are placed on circumference of a circle of radius 'd' as shown in figure. The electric field 
along x-axis at centre of circle is:  
 rhu fcUnq vkos'kksa dks ,d 'd' f=kT;k ds o`r dh ifjf/k ij fp=kkuqlkj j[kk tkrk gSA o`r ds dsUnz ij x-v{k ds vuqfn'k 
fo|qr {ks=k dh rhozrk crkb,A 
 
–2q
–4q 
+2q
30°
30°
30°
y-axis
x-axis
 
(1) 
2
0
d 4
q
? ?
  (2) 
2
0
d 4
3 q
? ?
  (3) 
2
0
d
3 q
? ?
  (4) 
2
0
d 2
3 q
? ?
 
Ans. (3) 
Page 2


     
 
      
    
     
     
 
                       
 
  
PAGE # 1 
 
 
PART : PHYSICS 
 
Single Choice Type   (,dy fodYih; izdkj) 
This section contains 20 Single choice questions. Each question has 4 choices (1), (2), (3) and (4) for its 
answer, out of which Only One is correct. 
bl [k.M esa 20 ,dy fodYih iz'u gSaA izR;sd iz'u ds 4 fodYi (1), (2), (3) rFkk (4) gSa] ftuesa ls flQZ ,d lgh gSA 
 
1. A block of mass m is connected at one end of spring fixed at other end having natural length ?0 and 
spring constant K. The block is rotated with constant angular speed ( ?) about the fixed end in gravity 
free space. The elongation in spring is–  
 ,d CykWd ftldk nzO;eku m gS dks izkdfrd yEckbZ ?0 rFkk cy fu;rkad K  dh fLizax ds ,d fljs ls tqM+k gqvk gS 
rFkk fLizax dk nwljk fljk tM+or~ gSA CykWd dks tM+or fljs ds ifjr% xq:Roghu LFkku esa fu;r dksf.k; pky ( ?) ls 
?kqek;k tkrk gS rks fLizax es f[kpko crkb, 
 (1) 
2
2
0
m k
m
? ?
? ?
    (2) 
2
2
0
m k
m
? ?
? ?
    (3) 
? ?
?
m k
m
2
0
?
    (4) 
? ?
?
m k
m
2
0
?
   
Ans. (1) 
Sol.  
? ? k, ?0
m
 
m ?
2 
( ?0 + x) = kx 
 
2
0
m
k
1
x ?
? ?
?
?
?
?
?
?
?
 
 x = 
2
2
0
m k
m
? ?
? ?
  
 
2. 3 point charges are placed on circumference of a circle of radius 'd' as shown in figure. The electric field 
along x-axis at centre of circle is:  
 rhu fcUnq vkos'kksa dks ,d 'd' f=kT;k ds o`r dh ifjf/k ij fp=kkuqlkj j[kk tkrk gSA o`r ds dsUnz ij x-v{k ds vuqfn'k 
fo|qr {ks=k dh rhozrk crkb,A 
 
–2q
–4q 
+2q
30°
30°
30°
y-axis
x-axis
 
(1) 
2
0
d 4
q
? ?
  (2) 
2
0
d 4
3 q
? ?
  (3) 
2
0
d
3 q
? ?
  (4) 
2
0
d 2
3 q
? ?
 
Ans. (3) 
     
 
      
    
     
     
 
                       
 
  
PAGE # 2 
 
Sol. 
 
2
d
q 4 k
2
d
q 4 k
 
? 30 
? 30
net
E
 
? ? ? 30 cos 2
d
kq 4
E
2
net
= 
2
0
d
3 q
? ?
 
 
3. Choose the correct P-V graph of ideal gas for given V-T graph. 
 vkn'kZ xSl ds fy,  V-T xzkQ fn;k x;k gS rks blds laxr P–V xzkQ crkb,A 
 
 
 (1) 
P 
V
z 
y 
x 
(2) 
P
V
z 
x 
y 
 (3)
P
V 
z y 
x 
(4) 
P 
V x
z 
y 
 
Ans. (1) 
4. Find the co-ordinates of centre of mass of the lamina, shown in figure. 
 fp=k esa fn[kkbZ xbZ ds IysV ds nzO;eku dsUn ds funsZ'kkad gksaxs % 
(0,3) 
 
(1,2) 
 
(2,3) 
 
(0,0) 
 
(1,0) 
 
 
 (1) 0.75, 1.75  (2) 0.75, 1.5  (3) 0.5, 1.75  (4) 0.5, 1.5 
Ans. (1) 
 
 
 
Page 3


     
 
      
    
     
     
 
                       
 
  
PAGE # 1 
 
 
PART : PHYSICS 
 
Single Choice Type   (,dy fodYih; izdkj) 
This section contains 20 Single choice questions. Each question has 4 choices (1), (2), (3) and (4) for its 
answer, out of which Only One is correct. 
bl [k.M esa 20 ,dy fodYih iz'u gSaA izR;sd iz'u ds 4 fodYi (1), (2), (3) rFkk (4) gSa] ftuesa ls flQZ ,d lgh gSA 
 
1. A block of mass m is connected at one end of spring fixed at other end having natural length ?0 and 
spring constant K. The block is rotated with constant angular speed ( ?) about the fixed end in gravity 
free space. The elongation in spring is–  
 ,d CykWd ftldk nzO;eku m gS dks izkdfrd yEckbZ ?0 rFkk cy fu;rkad K  dh fLizax ds ,d fljs ls tqM+k gqvk gS 
rFkk fLizax dk nwljk fljk tM+or~ gSA CykWd dks tM+or fljs ds ifjr% xq:Roghu LFkku esa fu;r dksf.k; pky ( ?) ls 
?kqek;k tkrk gS rks fLizax es f[kpko crkb, 
 (1) 
2
2
0
m k
m
? ?
? ?
    (2) 
2
2
0
m k
m
? ?
? ?
    (3) 
? ?
?
m k
m
2
0
?
    (4) 
? ?
?
m k
m
2
0
?
   
Ans. (1) 
Sol.  
? ? k, ?0
m
 
m ?
2 
( ?0 + x) = kx 
 
2
0
m
k
1
x ?
? ?
?
?
?
?
?
?
?
 
 x = 
2
2
0
m k
m
? ?
? ?
  
 
2. 3 point charges are placed on circumference of a circle of radius 'd' as shown in figure. The electric field 
along x-axis at centre of circle is:  
 rhu fcUnq vkos'kksa dks ,d 'd' f=kT;k ds o`r dh ifjf/k ij fp=kkuqlkj j[kk tkrk gSA o`r ds dsUnz ij x-v{k ds vuqfn'k 
fo|qr {ks=k dh rhozrk crkb,A 
 
–2q
–4q 
+2q
30°
30°
30°
y-axis
x-axis
 
(1) 
2
0
d 4
q
? ?
  (2) 
2
0
d 4
3 q
? ?
  (3) 
2
0
d
3 q
? ?
  (4) 
2
0
d 2
3 q
? ?
 
Ans. (3) 
     
 
      
    
     
     
 
                       
 
  
PAGE # 2 
 
Sol. 
 
2
d
q 4 k
2
d
q 4 k
 
? 30 
? 30
net
E
 
? ? ? 30 cos 2
d
kq 4
E
2
net
= 
2
0
d
3 q
? ?
 
 
3. Choose the correct P-V graph of ideal gas for given V-T graph. 
 vkn'kZ xSl ds fy,  V-T xzkQ fn;k x;k gS rks blds laxr P–V xzkQ crkb,A 
 
 
 (1) 
P 
V
z 
y 
x 
(2) 
P
V
z 
x 
y 
 (3)
P
V 
z y 
x 
(4) 
P 
V x
z 
y 
 
Ans. (1) 
4. Find the co-ordinates of centre of mass of the lamina, shown in figure. 
 fp=k esa fn[kkbZ xbZ ds IysV ds nzO;eku dsUn ds funsZ'kkad gksaxs % 
(0,3) 
 
(1,2) 
 
(2,3) 
 
(0,0) 
 
(1,0) 
 
 
 (1) 0.75, 1.75  (2) 0.75, 1.5  (3) 0.5, 1.75  (4) 0.5, 1.5 
Ans. (1) 
 
 
 
     
 
      
    
     
     
 
                       
 
  
PAGE # 3 
 
Sol.  
 
(0,3) 
 
(1,2) 
 
(2,3) 
 
(0,0) 
 
(1, 2.5) 
 
(0.5, 1) 
 
(1,0) 
 
 
 
cm
ˆ ˆ
i 5j
ˆ ˆ
1 j 1 i
2 2
r
2
? ? ? ?
? ? ? ? ?
? ? ? ?
? ? ? ?
? ? ? ?
?
?
  
  
 
cm
r
?
 = 
3 7
ˆ ˆ
i j
4 4
? 
 
5. Which graph correctly represents variation between relaxation time ( ?) of gas molecules with absolute 
temperature (T) of an ideal gas. 
 buesa ls dkSulk xzkQ vkn'kZ xSl v.kq ds foJkarh dky ( ?) vkSj ije rkieku T ds e/; lgh gSA 
 (1) 
 
? ?
1
T
 
(2) 
 
? ?
T 
  (3) 
 
? ?
1/T 
 
(4) 
 
? ?
T
 
Ans. (1) 
Sol. ? ? ? 
1
T
 
 
6. If two capacitors C1 & C2 are connected in parallel then equivalent capacitance is 10 ?F. If both 
capacitor are connected across 1V battery then energy stored by C2 is 4 times that of C1. Then the 
equivalent capacitance if they are connected in series is –   
 nks la/kkfj=k ftudh /kkfjrk,sa C1 & C2 gS dkss lekUrj Øe esa tksM+us ij izkIr rqY; /kkfjrk 10 ?F gSA ;fn nksuks la/kkfj=k 
dks 1V dh cSVjh ds lkFk tksM+k tkrk gS rks C2 esa laxzfgr ÅtkZ] C1 esa laxzfgr ÅtkZ dh 4 xquk gSA l/kkfj=kks dks Js.kh 
Øe esa tksM+us ij budh rqY; /kkfjrk D;k gksxhA  
 (1) 1.6 ?F  (2) 16 ?F  (3) 4 ?F   (4) 
1
4
?F 
Ans. (1) 
 
Page 4


     
 
      
    
     
     
 
                       
 
  
PAGE # 1 
 
 
PART : PHYSICS 
 
Single Choice Type   (,dy fodYih; izdkj) 
This section contains 20 Single choice questions. Each question has 4 choices (1), (2), (3) and (4) for its 
answer, out of which Only One is correct. 
bl [k.M esa 20 ,dy fodYih iz'u gSaA izR;sd iz'u ds 4 fodYi (1), (2), (3) rFkk (4) gSa] ftuesa ls flQZ ,d lgh gSA 
 
1. A block of mass m is connected at one end of spring fixed at other end having natural length ?0 and 
spring constant K. The block is rotated with constant angular speed ( ?) about the fixed end in gravity 
free space. The elongation in spring is–  
 ,d CykWd ftldk nzO;eku m gS dks izkdfrd yEckbZ ?0 rFkk cy fu;rkad K  dh fLizax ds ,d fljs ls tqM+k gqvk gS 
rFkk fLizax dk nwljk fljk tM+or~ gSA CykWd dks tM+or fljs ds ifjr% xq:Roghu LFkku esa fu;r dksf.k; pky ( ?) ls 
?kqek;k tkrk gS rks fLizax es f[kpko crkb, 
 (1) 
2
2
0
m k
m
? ?
? ?
    (2) 
2
2
0
m k
m
? ?
? ?
    (3) 
? ?
?
m k
m
2
0
?
    (4) 
? ?
?
m k
m
2
0
?
   
Ans. (1) 
Sol.  
? ? k, ?0
m
 
m ?
2 
( ?0 + x) = kx 
 
2
0
m
k
1
x ?
? ?
?
?
?
?
?
?
?
 
 x = 
2
2
0
m k
m
? ?
? ?
  
 
2. 3 point charges are placed on circumference of a circle of radius 'd' as shown in figure. The electric field 
along x-axis at centre of circle is:  
 rhu fcUnq vkos'kksa dks ,d 'd' f=kT;k ds o`r dh ifjf/k ij fp=kkuqlkj j[kk tkrk gSA o`r ds dsUnz ij x-v{k ds vuqfn'k 
fo|qr {ks=k dh rhozrk crkb,A 
 
–2q
–4q 
+2q
30°
30°
30°
y-axis
x-axis
 
(1) 
2
0
d 4
q
? ?
  (2) 
2
0
d 4
3 q
? ?
  (3) 
2
0
d
3 q
? ?
  (4) 
2
0
d 2
3 q
? ?
 
Ans. (3) 
     
 
      
    
     
     
 
                       
 
  
PAGE # 2 
 
Sol. 
 
2
d
q 4 k
2
d
q 4 k
 
? 30 
? 30
net
E
 
? ? ? 30 cos 2
d
kq 4
E
2
net
= 
2
0
d
3 q
? ?
 
 
3. Choose the correct P-V graph of ideal gas for given V-T graph. 
 vkn'kZ xSl ds fy,  V-T xzkQ fn;k x;k gS rks blds laxr P–V xzkQ crkb,A 
 
 
 (1) 
P 
V
z 
y 
x 
(2) 
P
V
z 
x 
y 
 (3)
P
V 
z y 
x 
(4) 
P 
V x
z 
y 
 
Ans. (1) 
4. Find the co-ordinates of centre of mass of the lamina, shown in figure. 
 fp=k esa fn[kkbZ xbZ ds IysV ds nzO;eku dsUn ds funsZ'kkad gksaxs % 
(0,3) 
 
(1,2) 
 
(2,3) 
 
(0,0) 
 
(1,0) 
 
 
 (1) 0.75, 1.75  (2) 0.75, 1.5  (3) 0.5, 1.75  (4) 0.5, 1.5 
Ans. (1) 
 
 
 
     
 
      
    
     
     
 
                       
 
  
PAGE # 3 
 
Sol.  
 
(0,3) 
 
(1,2) 
 
(2,3) 
 
(0,0) 
 
(1, 2.5) 
 
(0.5, 1) 
 
(1,0) 
 
 
 
cm
ˆ ˆ
i 5j
ˆ ˆ
1 j 1 i
2 2
r
2
? ? ? ?
? ? ? ? ?
? ? ? ?
? ? ? ?
? ? ? ?
?
?
  
  
 
cm
r
?
 = 
3 7
ˆ ˆ
i j
4 4
? 
 
5. Which graph correctly represents variation between relaxation time ( ?) of gas molecules with absolute 
temperature (T) of an ideal gas. 
 buesa ls dkSulk xzkQ vkn'kZ xSl v.kq ds foJkarh dky ( ?) vkSj ije rkieku T ds e/; lgh gSA 
 (1) 
 
? ?
1
T
 
(2) 
 
? ?
T 
  (3) 
 
? ?
1/T 
 
(4) 
 
? ?
T
 
Ans. (1) 
Sol. ? ? ? 
1
T
 
 
6. If two capacitors C1 & C2 are connected in parallel then equivalent capacitance is 10 ?F. If both 
capacitor are connected across 1V battery then energy stored by C2 is 4 times that of C1. Then the 
equivalent capacitance if they are connected in series is –   
 nks la/kkfj=k ftudh /kkfjrk,sa C1 & C2 gS dkss lekUrj Øe esa tksM+us ij izkIr rqY; /kkfjrk 10 ?F gSA ;fn nksuks la/kkfj=k 
dks 1V dh cSVjh ds lkFk tksM+k tkrk gS rks C2 esa laxzfgr ÅtkZ] C1 esa laxzfgr ÅtkZ dh 4 xquk gSA l/kkfj=kks dks Js.kh 
Øe esa tksM+us ij budh rqY; /kkfjrk D;k gksxhA  
 (1) 1.6 ?F  (2) 16 ?F  (3) 4 ?F   (4) 
1
4
?F 
Ans. (1) 
 
     
 
      
    
     
     
 
                       
 
  
PAGE # 4 
 
Sol.  
 
 
1V 
C1 
C2 
 
Given fn;k gS C1 + C2 = 10 ?F …(i) 
 
2 2
1 2
1 1
4 C V C V
2 2
? ?
?
? ?
? ?
 
 ? 4C1 = C2 …(ii) 
 from equation (i) & (ii) leh- (i) rFkk (ii) ls 
 C1 = 2 ?F 
 C2 = 8 ?F 
 If they are in series ;fn budks Js.kh Øe esa tksM+k tk, 
 Ceq. = 
1 2
1 2
C C
C C ?
 = 1.6 ?F   
 
7. A rod of mass 4m and length L is hinged at the mid point. A ball of mass 'm' moving with speed V in the 
plane of rod which is perpendicular to axis of rotation, strikes at one end at an angle of 45º and sticks to 
it. The angular velocity of system after collision is– 
 4m nzO;eku rFkk L yEckbZ dh NM+ e/; fcUnq ls fuyfEcr gSA 'm' nzO;eku dh xsan NM+ ds ry ¼tks fd ?kw.kZu v{k ds 
yEcor~ gS½ esa V pky ls xfr djrh gqbZ NM+ ds ,d fljs ls 45º dks.k ij VDdjk dj fpid tkrh gSA VDdj ds 
Ik'pkr fudk; dk dks.kh; osx Kkr dhft,s  
 (1) 
L 7
V 2 3
  (2) 
L 7
V 2
  (3) 
L 3
V 2
  (4) 
L 7
V 3
 
Ans. (1) 
Sol.  
 
L
O
2
V
 
2
V
 
m
4m
 
Loi = Lof 
 ? ?
?
?
?
?
?
?
?
?
? ? ?
4
mL
12
mL 4
2
L
2
mV
2 2
 
 
L 2 7
V 6
? ? = 
L 7
V 2 3
 
 
Page 5


     
 
      
    
     
     
 
                       
 
  
PAGE # 1 
 
 
PART : PHYSICS 
 
Single Choice Type   (,dy fodYih; izdkj) 
This section contains 20 Single choice questions. Each question has 4 choices (1), (2), (3) and (4) for its 
answer, out of which Only One is correct. 
bl [k.M esa 20 ,dy fodYih iz'u gSaA izR;sd iz'u ds 4 fodYi (1), (2), (3) rFkk (4) gSa] ftuesa ls flQZ ,d lgh gSA 
 
1. A block of mass m is connected at one end of spring fixed at other end having natural length ?0 and 
spring constant K. The block is rotated with constant angular speed ( ?) about the fixed end in gravity 
free space. The elongation in spring is–  
 ,d CykWd ftldk nzO;eku m gS dks izkdfrd yEckbZ ?0 rFkk cy fu;rkad K  dh fLizax ds ,d fljs ls tqM+k gqvk gS 
rFkk fLizax dk nwljk fljk tM+or~ gSA CykWd dks tM+or fljs ds ifjr% xq:Roghu LFkku esa fu;r dksf.k; pky ( ?) ls 
?kqek;k tkrk gS rks fLizax es f[kpko crkb, 
 (1) 
2
2
0
m k
m
? ?
? ?
    (2) 
2
2
0
m k
m
? ?
? ?
    (3) 
? ?
?
m k
m
2
0
?
    (4) 
? ?
?
m k
m
2
0
?
   
Ans. (1) 
Sol.  
? ? k, ?0
m
 
m ?
2 
( ?0 + x) = kx 
 
2
0
m
k
1
x ?
? ?
?
?
?
?
?
?
?
 
 x = 
2
2
0
m k
m
? ?
? ?
  
 
2. 3 point charges are placed on circumference of a circle of radius 'd' as shown in figure. The electric field 
along x-axis at centre of circle is:  
 rhu fcUnq vkos'kksa dks ,d 'd' f=kT;k ds o`r dh ifjf/k ij fp=kkuqlkj j[kk tkrk gSA o`r ds dsUnz ij x-v{k ds vuqfn'k 
fo|qr {ks=k dh rhozrk crkb,A 
 
–2q
–4q 
+2q
30°
30°
30°
y-axis
x-axis
 
(1) 
2
0
d 4
q
? ?
  (2) 
2
0
d 4
3 q
? ?
  (3) 
2
0
d
3 q
? ?
  (4) 
2
0
d 2
3 q
? ?
 
Ans. (3) 
     
 
      
    
     
     
 
                       
 
  
PAGE # 2 
 
Sol. 
 
2
d
q 4 k
2
d
q 4 k
 
? 30 
? 30
net
E
 
? ? ? 30 cos 2
d
kq 4
E
2
net
= 
2
0
d
3 q
? ?
 
 
3. Choose the correct P-V graph of ideal gas for given V-T graph. 
 vkn'kZ xSl ds fy,  V-T xzkQ fn;k x;k gS rks blds laxr P–V xzkQ crkb,A 
 
 
 (1) 
P 
V
z 
y 
x 
(2) 
P
V
z 
x 
y 
 (3)
P
V 
z y 
x 
(4) 
P 
V x
z 
y 
 
Ans. (1) 
4. Find the co-ordinates of centre of mass of the lamina, shown in figure. 
 fp=k esa fn[kkbZ xbZ ds IysV ds nzO;eku dsUn ds funsZ'kkad gksaxs % 
(0,3) 
 
(1,2) 
 
(2,3) 
 
(0,0) 
 
(1,0) 
 
 
 (1) 0.75, 1.75  (2) 0.75, 1.5  (3) 0.5, 1.75  (4) 0.5, 1.5 
Ans. (1) 
 
 
 
     
 
      
    
     
     
 
                       
 
  
PAGE # 3 
 
Sol.  
 
(0,3) 
 
(1,2) 
 
(2,3) 
 
(0,0) 
 
(1, 2.5) 
 
(0.5, 1) 
 
(1,0) 
 
 
 
cm
ˆ ˆ
i 5j
ˆ ˆ
1 j 1 i
2 2
r
2
? ? ? ?
? ? ? ? ?
? ? ? ?
? ? ? ?
? ? ? ?
?
?
  
  
 
cm
r
?
 = 
3 7
ˆ ˆ
i j
4 4
? 
 
5. Which graph correctly represents variation between relaxation time ( ?) of gas molecules with absolute 
temperature (T) of an ideal gas. 
 buesa ls dkSulk xzkQ vkn'kZ xSl v.kq ds foJkarh dky ( ?) vkSj ije rkieku T ds e/; lgh gSA 
 (1) 
 
? ?
1
T
 
(2) 
 
? ?
T 
  (3) 
 
? ?
1/T 
 
(4) 
 
? ?
T
 
Ans. (1) 
Sol. ? ? ? 
1
T
 
 
6. If two capacitors C1 & C2 are connected in parallel then equivalent capacitance is 10 ?F. If both 
capacitor are connected across 1V battery then energy stored by C2 is 4 times that of C1. Then the 
equivalent capacitance if they are connected in series is –   
 nks la/kkfj=k ftudh /kkfjrk,sa C1 & C2 gS dkss lekUrj Øe esa tksM+us ij izkIr rqY; /kkfjrk 10 ?F gSA ;fn nksuks la/kkfj=k 
dks 1V dh cSVjh ds lkFk tksM+k tkrk gS rks C2 esa laxzfgr ÅtkZ] C1 esa laxzfgr ÅtkZ dh 4 xquk gSA l/kkfj=kks dks Js.kh 
Øe esa tksM+us ij budh rqY; /kkfjrk D;k gksxhA  
 (1) 1.6 ?F  (2) 16 ?F  (3) 4 ?F   (4) 
1
4
?F 
Ans. (1) 
 
     
 
      
    
     
     
 
                       
 
  
PAGE # 4 
 
Sol.  
 
 
1V 
C1 
C2 
 
Given fn;k gS C1 + C2 = 10 ?F …(i) 
 
2 2
1 2
1 1
4 C V C V
2 2
? ?
?
? ?
? ?
 
 ? 4C1 = C2 …(ii) 
 from equation (i) & (ii) leh- (i) rFkk (ii) ls 
 C1 = 2 ?F 
 C2 = 8 ?F 
 If they are in series ;fn budks Js.kh Øe esa tksM+k tk, 
 Ceq. = 
1 2
1 2
C C
C C ?
 = 1.6 ?F   
 
7. A rod of mass 4m and length L is hinged at the mid point. A ball of mass 'm' moving with speed V in the 
plane of rod which is perpendicular to axis of rotation, strikes at one end at an angle of 45º and sticks to 
it. The angular velocity of system after collision is– 
 4m nzO;eku rFkk L yEckbZ dh NM+ e/; fcUnq ls fuyfEcr gSA 'm' nzO;eku dh xsan NM+ ds ry ¼tks fd ?kw.kZu v{k ds 
yEcor~ gS½ esa V pky ls xfr djrh gqbZ NM+ ds ,d fljs ls 45º dks.k ij VDdjk dj fpid tkrh gSA VDdj ds 
Ik'pkr fudk; dk dks.kh; osx Kkr dhft,s  
 (1) 
L 7
V 2 3
  (2) 
L 7
V 2
  (3) 
L 3
V 2
  (4) 
L 7
V 3
 
Ans. (1) 
Sol.  
 
L
O
2
V
 
2
V
 
m
4m
 
Loi = Lof 
 ? ?
?
?
?
?
?
?
?
?
? ? ?
4
mL
12
mL 4
2
L
2
mV
2 2
 
 
L 2 7
V 6
? ? = 
L 7
V 2 3
 
 
     
 
      
    
     
     
 
                       
 
  
PAGE # 5 
 
8. Two photons of energy 4eV and 4.5eV are incident on two metals A and B respectively. Maximum 
kinetic energy for ejected electron is TA for A and TB = TA – 1.5eV for metal B. Relation between  
de-Broglie wavelengths of ejected electron of A and B are ?B = 2 ?A. The work function of metal B is– 
 nks /kkrq A rFkk B fn xbZ gSA vkirhr QksVksuks dh ÅtkZ Øe'k% 4eV rFkk 4.5eV gSA mRlftZr bysDVªkWu dh vf/kdre 
xfrt ÅtkZ /kkrq A ds fy, TA rFkk /kkrq B ds fy, TB = TA – 1.5eV gSA /kkrq A rFkk B ls mRlftZr bysDVªkWuksa dh 
Mh&czksxyh rajxnS/;ksaZ esa lEc/k ?B = 2 ?A gSA /kkrq B ds fy, dk;Z Qyu Kkr djksA  
 (1) 3 eV   (2) 1.5 eV  (3) 4.5 eV  (4) 4 eV 
Ans. (4) 
Sol. Relation between De-Broglie wavelength and K.E. is 
 Mh&czksxyh rajxnS/;Z rFkk xfrt ÅtkZ esa lEca/k  
 
e
m ) KE ( 2
h
? ? ?
KE
1
? ? 
 
A
B
B
A
KE
KE
?
?
?
 
 ? ?
A
A
T
5 . 1 T
2
1 ?
?  ? ? TA = 2 eV 
? ? ? KEB = 2 – 1.5 = 0.5 eV 
?B = 4.5 – 0.5 = 4 eV ?
    
9. There is a potentiometer wire of length 1200 cm and 60 mA current is flowing in it. A battery of emf 5V 
and internal resistance of 20 ? is balanced on potentiometer wire with balancing length 1000 cm. The 
resistance of potentiometer wire is– 
 ,d foHkoekih rkj ftldh yEckbZ 1200 cm gS rFkk blesa /kkjk 60 mA cg jgh gSA ;fn ,d 5V fo|qr okgd cy dh 
cSVjh ftldk vkUrjhd izfrjks/k 20 ? ?gS dh foHkoekih rkj ij larqfyr yEckbZ 1000 cm gSA foHkekih dk izfrjks/k Kkr 
djksA  
 (1) 80 ? ? ? (2) 100 ? ? ? (3) 120 ? ? ? (4) 60 ? ?
Ans. (2) 
Sol.  
 
 
VP 
5V
20 ? 
1000 cm
L = 1200 cm
G
? = 60 mA
 
Potential gradient foHko iru = 
1200
V
1000
5
P
? 
    VP = 6V 
 and rFkk RP = 
3
P
10 60
6 V
?
?
?
?
 = 100 ? ?