Page 1
PHYSICS
SECTION - A
Multiple Choice Questions: This section contains 20
multiple choice questions. Each question has 4 choices
(1), (2), (3) and (4), out of which ONLY ONE is correct.
Choose the correct answer :
1. A small toy starts moving from the position of rest
under a constant acceleration. If it travels a
distance of 10 m in t s, the distance travelled by the
toy in the next t s will be :
(A) 10 m (B) 20 m
(C) 30 m (D) 40 m
Answer (C)
Sol.
2
1
10 m
2
at =
2
1
(2 ) 40 m
2
at =
? Distance travelled in next t s
= 40 – 10 = 30 m
2. At what temperature a gold ring of diameter
6.230 cm be heated so that it can be fitted on a
wooden bangle of diameter 6.241 cm? Both the
diameters have been measured at room
temperature (27°C).
(Given: coefficient of linear thermal expansion of
gold aL = 1.4 × 10
–5
K
–1
)
(A) 125.7°C (B) 91.7°C
(C) 425.7°C (D) 152.7°C
Answer (D)
Sol. ?D = Da?T
5
0.011
6.230 1.4 10
T
-
?=
××
= 126.11°C
? T f = T + ?T
= (27 + 126.11)°C
= 153.11°C
? Option (D) is correct
3. Two point charges Q each are placed at a distance
d apart. A third point charge q is placed at a
distance x from mid-point on the perpendicular
bisector. The value of x at which charge q will
experience the maximum Coulombs force is :
(A) x = d (B)
2
=
d
x
(C)
2
=
d
x (D)
22
=
d
x
Answer (D)
Sol. Force experienced by the charge q
3
2
2
2
2
kQqx
F
d
x
=
? ?
??
+ ? ? ??
?? ? ?
For maximum Coulomb’s force for x
0
dF
dx
=
On solving
22
d
x =
4. The speed of light in media ‘A’ and ‘B’ are
2.0 × 10
10
cm/s and 1.5 × 10
10
cm/s respectively. A
ray of light enters from the medium B to A at an
incident angle ‘?’. If the ray suffers total internal
reflection, then
(A)
1
3
sin
4
-
??
?=
??
??
(B)
1
2
sin
3
-
? ?
?>
? ?
? ?
(C)
1
3
sin
4
-
??
?<
??
??
(D)
1
3
sin
4
-
??
?>
??
??
Answer (D)
Sol.
8
8
3 10
1.5
2 10
A
×
µ= =
×
8
8
3 10
2
1.5 10
B
×
µ= =
×
For TIR
? > i c
1
1.5
sin
2
-
??
?>
??
??
1
3
sin
4
-
??
?>
??
??
Page 2
PHYSICS
SECTION - A
Multiple Choice Questions: This section contains 20
multiple choice questions. Each question has 4 choices
(1), (2), (3) and (4), out of which ONLY ONE is correct.
Choose the correct answer :
1. A small toy starts moving from the position of rest
under a constant acceleration. If it travels a
distance of 10 m in t s, the distance travelled by the
toy in the next t s will be :
(A) 10 m (B) 20 m
(C) 30 m (D) 40 m
Answer (C)
Sol.
2
1
10 m
2
at =
2
1
(2 ) 40 m
2
at =
? Distance travelled in next t s
= 40 – 10 = 30 m
2. At what temperature a gold ring of diameter
6.230 cm be heated so that it can be fitted on a
wooden bangle of diameter 6.241 cm? Both the
diameters have been measured at room
temperature (27°C).
(Given: coefficient of linear thermal expansion of
gold aL = 1.4 × 10
–5
K
–1
)
(A) 125.7°C (B) 91.7°C
(C) 425.7°C (D) 152.7°C
Answer (D)
Sol. ?D = Da?T
5
0.011
6.230 1.4 10
T
-
?=
××
= 126.11°C
? T f = T + ?T
= (27 + 126.11)°C
= 153.11°C
? Option (D) is correct
3. Two point charges Q each are placed at a distance
d apart. A third point charge q is placed at a
distance x from mid-point on the perpendicular
bisector. The value of x at which charge q will
experience the maximum Coulombs force is :
(A) x = d (B)
2
=
d
x
(C)
2
=
d
x (D)
22
=
d
x
Answer (D)
Sol. Force experienced by the charge q
3
2
2
2
2
kQqx
F
d
x
=
? ?
??
+ ? ? ??
?? ? ?
For maximum Coulomb’s force for x
0
dF
dx
=
On solving
22
d
x =
4. The speed of light in media ‘A’ and ‘B’ are
2.0 × 10
10
cm/s and 1.5 × 10
10
cm/s respectively. A
ray of light enters from the medium B to A at an
incident angle ‘?’. If the ray suffers total internal
reflection, then
(A)
1
3
sin
4
-
??
?=
??
??
(B)
1
2
sin
3
-
? ?
?>
? ?
? ?
(C)
1
3
sin
4
-
??
?<
??
??
(D)
1
3
sin
4
-
??
?>
??
??
Answer (D)
Sol.
8
8
3 10
1.5
2 10
A
×
µ= =
×
8
8
3 10
2
1.5 10
B
×
µ= =
×
For TIR
? > i c
1
1.5
sin
2
-
??
?>
??
??
1
3
sin
4
-
??
?>
??
??
5. In the following nuclear reaction,
1 2 34
-
aß a ?
?? ? ?? ? ? ?? ? ?? ? DD D D D
Mass number of D is 182 and atomic number is 74.
Mass number and atomic number of D4 respectively
will be _____
(A) 174 and 71
(B) 174 and 69
(C) 172 and 69
(D) 172 and 71
Answer (A)
Sol. Equivalent reaction can be written as
D ?? D4 + 2a + ß
–
+ ?
? Mass number of D4 = Mass number of D – 2 × 4
= 182 – 8 = 174
? Atomic number of D4
= Atomic number of D – 2 × 2 + 1
= 74 – 4 + 1 = 71
6. The electric field at a point associated with a light
wave is given by
E = 200[sin(6 × 10
15
)t + sin(9 × 10
15
)t] Vm
–1
Given : h = 4.14 × 10
–15
eVs
If this light falls on a metal surface having a work
function of 2.50 eV, the maximum kinetic energy of
the photoelectrons will be
(A) 1.90 eV
(B) 3.27 eV
(C) 3.60 eV
(D) 3.42 eV
Answer (D)
Sol. Frequency of EM waves =
15
6
10
2
×
p
and
15
9
10
2
×
p
Energy of one photon of these waves
15 15
6
eV 4.14 10 10
2
-
? ?
= × ××
? ?
p ? ?
and
15 15
9
eV 4.14 10 10
2
-
? ?
× ××
? ?
p ? ?
= 3.95 eV and 5.93 eV
? Energy of maximum energetic electrons
= 5.93 – 2.50 = 3.43 eV
7. A capacitor is discharging through a resistor R.
Consider in time t1, the energy stored in the
capacitor reduces to half of its initial value and in
time t2, the charge stored reduces to one eighth of
its initial value. The ratio
1
2
t
t
will be
(A)
1
2
(B)
1
3
(C)
1
4
(D)
1
6
Answer (D)
Sol. For a discharging capacitor when energy reduces
to half the charge would become
1
2
times the
initial value.
?
1
1/2
/
1
2
t
e
-t ? ?
=
? ?
? ?
Similarly,
2
3
/
1
2
t
e
-t ? ?
=
? ?
? ?
?
1
2
1
6
t
t
=
8. Starting with the same initial conditions, an ideal
gas expands from volume V1 to V2 in three different
ways. The work done by the gas is W1 if the process
is purely isothermal, W2, if the process is purely
adiabatic and W3 if the process is purely isobaric.
Then, choose the correct option.
(A) W1 < W2 < W3
(B) W2 < W3 < W1
(C) W3 < W1 < W2
(D) W2 < W1 < W3
Answer (D)
Sol.
Comparing the area under the PV graph
A3 > A1 > A2
? W3 > W1 > W2
Page 3
PHYSICS
SECTION - A
Multiple Choice Questions: This section contains 20
multiple choice questions. Each question has 4 choices
(1), (2), (3) and (4), out of which ONLY ONE is correct.
Choose the correct answer :
1. A small toy starts moving from the position of rest
under a constant acceleration. If it travels a
distance of 10 m in t s, the distance travelled by the
toy in the next t s will be :
(A) 10 m (B) 20 m
(C) 30 m (D) 40 m
Answer (C)
Sol.
2
1
10 m
2
at =
2
1
(2 ) 40 m
2
at =
? Distance travelled in next t s
= 40 – 10 = 30 m
2. At what temperature a gold ring of diameter
6.230 cm be heated so that it can be fitted on a
wooden bangle of diameter 6.241 cm? Both the
diameters have been measured at room
temperature (27°C).
(Given: coefficient of linear thermal expansion of
gold aL = 1.4 × 10
–5
K
–1
)
(A) 125.7°C (B) 91.7°C
(C) 425.7°C (D) 152.7°C
Answer (D)
Sol. ?D = Da?T
5
0.011
6.230 1.4 10
T
-
?=
××
= 126.11°C
? T f = T + ?T
= (27 + 126.11)°C
= 153.11°C
? Option (D) is correct
3. Two point charges Q each are placed at a distance
d apart. A third point charge q is placed at a
distance x from mid-point on the perpendicular
bisector. The value of x at which charge q will
experience the maximum Coulombs force is :
(A) x = d (B)
2
=
d
x
(C)
2
=
d
x (D)
22
=
d
x
Answer (D)
Sol. Force experienced by the charge q
3
2
2
2
2
kQqx
F
d
x
=
? ?
??
+ ? ? ??
?? ? ?
For maximum Coulomb’s force for x
0
dF
dx
=
On solving
22
d
x =
4. The speed of light in media ‘A’ and ‘B’ are
2.0 × 10
10
cm/s and 1.5 × 10
10
cm/s respectively. A
ray of light enters from the medium B to A at an
incident angle ‘?’. If the ray suffers total internal
reflection, then
(A)
1
3
sin
4
-
??
?=
??
??
(B)
1
2
sin
3
-
? ?
?>
? ?
? ?
(C)
1
3
sin
4
-
??
?<
??
??
(D)
1
3
sin
4
-
??
?>
??
??
Answer (D)
Sol.
8
8
3 10
1.5
2 10
A
×
µ= =
×
8
8
3 10
2
1.5 10
B
×
µ= =
×
For TIR
? > i c
1
1.5
sin
2
-
??
?>
??
??
1
3
sin
4
-
??
?>
??
??
5. In the following nuclear reaction,
1 2 34
-
aß a ?
?? ? ?? ? ? ?? ? ?? ? DD D D D
Mass number of D is 182 and atomic number is 74.
Mass number and atomic number of D4 respectively
will be _____
(A) 174 and 71
(B) 174 and 69
(C) 172 and 69
(D) 172 and 71
Answer (A)
Sol. Equivalent reaction can be written as
D ?? D4 + 2a + ß
–
+ ?
? Mass number of D4 = Mass number of D – 2 × 4
= 182 – 8 = 174
? Atomic number of D4
= Atomic number of D – 2 × 2 + 1
= 74 – 4 + 1 = 71
6. The electric field at a point associated with a light
wave is given by
E = 200[sin(6 × 10
15
)t + sin(9 × 10
15
)t] Vm
–1
Given : h = 4.14 × 10
–15
eVs
If this light falls on a metal surface having a work
function of 2.50 eV, the maximum kinetic energy of
the photoelectrons will be
(A) 1.90 eV
(B) 3.27 eV
(C) 3.60 eV
(D) 3.42 eV
Answer (D)
Sol. Frequency of EM waves =
15
6
10
2
×
p
and
15
9
10
2
×
p
Energy of one photon of these waves
15 15
6
eV 4.14 10 10
2
-
? ?
= × ××
? ?
p ? ?
and
15 15
9
eV 4.14 10 10
2
-
? ?
× ××
? ?
p ? ?
= 3.95 eV and 5.93 eV
? Energy of maximum energetic electrons
= 5.93 – 2.50 = 3.43 eV
7. A capacitor is discharging through a resistor R.
Consider in time t1, the energy stored in the
capacitor reduces to half of its initial value and in
time t2, the charge stored reduces to one eighth of
its initial value. The ratio
1
2
t
t
will be
(A)
1
2
(B)
1
3
(C)
1
4
(D)
1
6
Answer (D)
Sol. For a discharging capacitor when energy reduces
to half the charge would become
1
2
times the
initial value.
?
1
1/2
/
1
2
t
e
-t ? ?
=
? ?
? ?
Similarly,
2
3
/
1
2
t
e
-t ? ?
=
? ?
? ?
?
1
2
1
6
t
t
=
8. Starting with the same initial conditions, an ideal
gas expands from volume V1 to V2 in three different
ways. The work done by the gas is W1 if the process
is purely isothermal, W2, if the process is purely
adiabatic and W3 if the process is purely isobaric.
Then, choose the correct option.
(A) W1 < W2 < W3
(B) W2 < W3 < W1
(C) W3 < W1 < W2
(D) W2 < W1 < W3
Answer (D)
Sol.
Comparing the area under the PV graph
A3 > A1 > A2
? W3 > W1 > W2
9. Two long current carrying conductors are placed
parallel to each other at a distance of 8 cm between
them. The magnitude of magnetic field produced at
mid-point between the two conductors due to
current flowing in them is 30 µT. The equal current
flowing in the two conductors is:
(A) 30 A in the same direction
(B) 30 A in the opposite direction
(C) 60 A in the opposite direction
(D) 300 A in the opposite direction
Answer (B)
Sol. As Bnet ? 0 that is the wires are carrying current in
opposite direction.
6 0
2
2
30 10 T
2 (4 10 )
I
-
-
µ×
= ×
p×
?
6
6
30 10
A
10
I
-
-
×
= = 30 A in opposite direction.
10. The time period of a satellite revolving around earth
in a given orbit is 7 hours. If the radius of orbit is
increased to three times its previous value, then
approximate new time period of the satellite will be
(A) 40 hours (B) 36 hours
(C) 30 hours (D) 25 hours
Answer (B)
Sol.
3
2 22
21
1
R
TT
R
??
=
??
??
? ( )
3/2
2
7 5.2 7
3
T= ט ×
2
36 hrs T ?
11. The TV transmission tower at a particular station
has a height of 125 m. For doubling the coverage
of its range, the height of the tower should be
increased by
(A) 125 m (B) 250 m
(C) 375 m (D) 500 m
Answer (C)
Sol. Range 2 Re = Rh
Let the height be h' to double the range so
2 2 Re ' = Rh
On solving h' = 4h
h' = 500 m
So ?h = 375 m
12. The motion of a simple pendulum executing S.H.M.
is represented by the following equation.
y = A sin(pt + f), where time is measured in second.
The length of pendulum is
(A) 97.23 cm (B) 25.3 cm
(C) 99.4 cm (D) 406.1 cm
Answer (C)
Sol. ?= p =
?
g
So
2
=
p
?
g
? 99.4 cm (Nearest value)
13. A vessel contains 16 g of hydrogen and 128 g of
oxygen at standard temperature and pressure. The
volume of the vessel in cm
3
is:
(A) 72 × 10
5
(B) 32 × 10
5
(C) 27 × 10
4
(D) 54 × 10
4
Answer (C)
Sol. Total number of moles are
22
HO
nn n = +
16 128
2 32
= +
= 12 moles
Using PV = nRT
=
nRT
V
P
3
5
12 8.31 273.15
m
10
××
=
= 0.27 m
3
= 27 × 10
4
cm
3
14. Given below are two statements:
Statement I: The electric force changes the speed
of the charged particle and hence changes its
kinetic energy; whereas the magnetic force does
not change the kinetic energy of the charged
particle.
Statement II: The electric force accelerates the
positively charged particle perpendicular to the
direction of electric field. The magnetic force
accelerates the moving charged particle along the
direction of magnetic field.
In the light of the above statements, choose the
most appropriate answer from the options given
below:
Page 4
PHYSICS
SECTION - A
Multiple Choice Questions: This section contains 20
multiple choice questions. Each question has 4 choices
(1), (2), (3) and (4), out of which ONLY ONE is correct.
Choose the correct answer :
1. A small toy starts moving from the position of rest
under a constant acceleration. If it travels a
distance of 10 m in t s, the distance travelled by the
toy in the next t s will be :
(A) 10 m (B) 20 m
(C) 30 m (D) 40 m
Answer (C)
Sol.
2
1
10 m
2
at =
2
1
(2 ) 40 m
2
at =
? Distance travelled in next t s
= 40 – 10 = 30 m
2. At what temperature a gold ring of diameter
6.230 cm be heated so that it can be fitted on a
wooden bangle of diameter 6.241 cm? Both the
diameters have been measured at room
temperature (27°C).
(Given: coefficient of linear thermal expansion of
gold aL = 1.4 × 10
–5
K
–1
)
(A) 125.7°C (B) 91.7°C
(C) 425.7°C (D) 152.7°C
Answer (D)
Sol. ?D = Da?T
5
0.011
6.230 1.4 10
T
-
?=
××
= 126.11°C
? T f = T + ?T
= (27 + 126.11)°C
= 153.11°C
? Option (D) is correct
3. Two point charges Q each are placed at a distance
d apart. A third point charge q is placed at a
distance x from mid-point on the perpendicular
bisector. The value of x at which charge q will
experience the maximum Coulombs force is :
(A) x = d (B)
2
=
d
x
(C)
2
=
d
x (D)
22
=
d
x
Answer (D)
Sol. Force experienced by the charge q
3
2
2
2
2
kQqx
F
d
x
=
? ?
??
+ ? ? ??
?? ? ?
For maximum Coulomb’s force for x
0
dF
dx
=
On solving
22
d
x =
4. The speed of light in media ‘A’ and ‘B’ are
2.0 × 10
10
cm/s and 1.5 × 10
10
cm/s respectively. A
ray of light enters from the medium B to A at an
incident angle ‘?’. If the ray suffers total internal
reflection, then
(A)
1
3
sin
4
-
??
?=
??
??
(B)
1
2
sin
3
-
? ?
?>
? ?
? ?
(C)
1
3
sin
4
-
??
?<
??
??
(D)
1
3
sin
4
-
??
?>
??
??
Answer (D)
Sol.
8
8
3 10
1.5
2 10
A
×
µ= =
×
8
8
3 10
2
1.5 10
B
×
µ= =
×
For TIR
? > i c
1
1.5
sin
2
-
??
?>
??
??
1
3
sin
4
-
??
?>
??
??
5. In the following nuclear reaction,
1 2 34
-
aß a ?
?? ? ?? ? ? ?? ? ?? ? DD D D D
Mass number of D is 182 and atomic number is 74.
Mass number and atomic number of D4 respectively
will be _____
(A) 174 and 71
(B) 174 and 69
(C) 172 and 69
(D) 172 and 71
Answer (A)
Sol. Equivalent reaction can be written as
D ?? D4 + 2a + ß
–
+ ?
? Mass number of D4 = Mass number of D – 2 × 4
= 182 – 8 = 174
? Atomic number of D4
= Atomic number of D – 2 × 2 + 1
= 74 – 4 + 1 = 71
6. The electric field at a point associated with a light
wave is given by
E = 200[sin(6 × 10
15
)t + sin(9 × 10
15
)t] Vm
–1
Given : h = 4.14 × 10
–15
eVs
If this light falls on a metal surface having a work
function of 2.50 eV, the maximum kinetic energy of
the photoelectrons will be
(A) 1.90 eV
(B) 3.27 eV
(C) 3.60 eV
(D) 3.42 eV
Answer (D)
Sol. Frequency of EM waves =
15
6
10
2
×
p
and
15
9
10
2
×
p
Energy of one photon of these waves
15 15
6
eV 4.14 10 10
2
-
? ?
= × ××
? ?
p ? ?
and
15 15
9
eV 4.14 10 10
2
-
? ?
× ××
? ?
p ? ?
= 3.95 eV and 5.93 eV
? Energy of maximum energetic electrons
= 5.93 – 2.50 = 3.43 eV
7. A capacitor is discharging through a resistor R.
Consider in time t1, the energy stored in the
capacitor reduces to half of its initial value and in
time t2, the charge stored reduces to one eighth of
its initial value. The ratio
1
2
t
t
will be
(A)
1
2
(B)
1
3
(C)
1
4
(D)
1
6
Answer (D)
Sol. For a discharging capacitor when energy reduces
to half the charge would become
1
2
times the
initial value.
?
1
1/2
/
1
2
t
e
-t ? ?
=
? ?
? ?
Similarly,
2
3
/
1
2
t
e
-t ? ?
=
? ?
? ?
?
1
2
1
6
t
t
=
8. Starting with the same initial conditions, an ideal
gas expands from volume V1 to V2 in three different
ways. The work done by the gas is W1 if the process
is purely isothermal, W2, if the process is purely
adiabatic and W3 if the process is purely isobaric.
Then, choose the correct option.
(A) W1 < W2 < W3
(B) W2 < W3 < W1
(C) W3 < W1 < W2
(D) W2 < W1 < W3
Answer (D)
Sol.
Comparing the area under the PV graph
A3 > A1 > A2
? W3 > W1 > W2
9. Two long current carrying conductors are placed
parallel to each other at a distance of 8 cm between
them. The magnitude of magnetic field produced at
mid-point between the two conductors due to
current flowing in them is 30 µT. The equal current
flowing in the two conductors is:
(A) 30 A in the same direction
(B) 30 A in the opposite direction
(C) 60 A in the opposite direction
(D) 300 A in the opposite direction
Answer (B)
Sol. As Bnet ? 0 that is the wires are carrying current in
opposite direction.
6 0
2
2
30 10 T
2 (4 10 )
I
-
-
µ×
= ×
p×
?
6
6
30 10
A
10
I
-
-
×
= = 30 A in opposite direction.
10. The time period of a satellite revolving around earth
in a given orbit is 7 hours. If the radius of orbit is
increased to three times its previous value, then
approximate new time period of the satellite will be
(A) 40 hours (B) 36 hours
(C) 30 hours (D) 25 hours
Answer (B)
Sol.
3
2 22
21
1
R
TT
R
??
=
??
??
? ( )
3/2
2
7 5.2 7
3
T= ט ×
2
36 hrs T ?
11. The TV transmission tower at a particular station
has a height of 125 m. For doubling the coverage
of its range, the height of the tower should be
increased by
(A) 125 m (B) 250 m
(C) 375 m (D) 500 m
Answer (C)
Sol. Range 2 Re = Rh
Let the height be h' to double the range so
2 2 Re ' = Rh
On solving h' = 4h
h' = 500 m
So ?h = 375 m
12. The motion of a simple pendulum executing S.H.M.
is represented by the following equation.
y = A sin(pt + f), where time is measured in second.
The length of pendulum is
(A) 97.23 cm (B) 25.3 cm
(C) 99.4 cm (D) 406.1 cm
Answer (C)
Sol. ?= p =
?
g
So
2
=
p
?
g
? 99.4 cm (Nearest value)
13. A vessel contains 16 g of hydrogen and 128 g of
oxygen at standard temperature and pressure. The
volume of the vessel in cm
3
is:
(A) 72 × 10
5
(B) 32 × 10
5
(C) 27 × 10
4
(D) 54 × 10
4
Answer (C)
Sol. Total number of moles are
22
HO
nn n = +
16 128
2 32
= +
= 12 moles
Using PV = nRT
=
nRT
V
P
3
5
12 8.31 273.15
m
10
××
=
= 0.27 m
3
= 27 × 10
4
cm
3
14. Given below are two statements:
Statement I: The electric force changes the speed
of the charged particle and hence changes its
kinetic energy; whereas the magnetic force does
not change the kinetic energy of the charged
particle.
Statement II: The electric force accelerates the
positively charged particle perpendicular to the
direction of electric field. The magnetic force
accelerates the moving charged particle along the
direction of magnetic field.
In the light of the above statements, choose the
most appropriate answer from the options given
below:
(A) Both statement I and statement II are correct
(B) Both statement I and statement II are incorrect
(C) Statement I is correct but statement II is
incorrect
(D) Statement I is incorrect but statement II is
correct
Answer (C)
Sol. Electric field accelerates the particle in the direction
of field
( )
= =
??
?
F qE maand magnetic field
accelerates the particle perpendicular to the field
( )
= ×=
??
? ?
F qv B ma
15. A block of mass 40 kg slides over a surface, when
a mass of 4 kg is suspended through an
inextensible massless string passing over
frictionless pulley as shown below.
The coefficient of kinetic friction between the
surface and block is 0.02. The acceleration of block
is (Given g = 10 ms
–2
.)
(A) 1 ms
–2
(B) 1/5 ms
–2
(C) 4/5 ms
–2
(D) 8/11 ms
–2
Answer (D)
Sol.
max
N = µ
r
f
= 0.02 × 400
= 8 N
Let the acceleration is a as shown then.
40 – T = 4a
T – 8 = 40a
?
2
32 8
m/s
44 11
= = a
16. In the given figure, the block of mass m is dropped
from the point ‘A’. The expression for kinetic energy
of block when it reaches point ‘B’ is
(A)
2
0
1
2
mgy (B)
2
1
2
mgy
(C) mg(y – y0) (D) mgy0
Answer (D)
Sol. Loss is potential energy = gain in kinetic energy
– (mg(y – y0) – mgy) = KE – 0
? KE = mgy0
17. A block of mass M placed inside a box descends
vertically with acceleration ‘a’. The block exerts a
force equal to one-fourth of its weight on the floor of
the box.
The value of ‘a’ will be
(A)
4
g
(B)
2
g
(C)
3
4
g
(D) g
Answer (C)
Sol.
Using Newton’s second law
4
mg
mg ma -=
?
3
4
g
a =
Page 5
PHYSICS
SECTION - A
Multiple Choice Questions: This section contains 20
multiple choice questions. Each question has 4 choices
(1), (2), (3) and (4), out of which ONLY ONE is correct.
Choose the correct answer :
1. A small toy starts moving from the position of rest
under a constant acceleration. If it travels a
distance of 10 m in t s, the distance travelled by the
toy in the next t s will be :
(A) 10 m (B) 20 m
(C) 30 m (D) 40 m
Answer (C)
Sol.
2
1
10 m
2
at =
2
1
(2 ) 40 m
2
at =
? Distance travelled in next t s
= 40 – 10 = 30 m
2. At what temperature a gold ring of diameter
6.230 cm be heated so that it can be fitted on a
wooden bangle of diameter 6.241 cm? Both the
diameters have been measured at room
temperature (27°C).
(Given: coefficient of linear thermal expansion of
gold aL = 1.4 × 10
–5
K
–1
)
(A) 125.7°C (B) 91.7°C
(C) 425.7°C (D) 152.7°C
Answer (D)
Sol. ?D = Da?T
5
0.011
6.230 1.4 10
T
-
?=
××
= 126.11°C
? T f = T + ?T
= (27 + 126.11)°C
= 153.11°C
? Option (D) is correct
3. Two point charges Q each are placed at a distance
d apart. A third point charge q is placed at a
distance x from mid-point on the perpendicular
bisector. The value of x at which charge q will
experience the maximum Coulombs force is :
(A) x = d (B)
2
=
d
x
(C)
2
=
d
x (D)
22
=
d
x
Answer (D)
Sol. Force experienced by the charge q
3
2
2
2
2
kQqx
F
d
x
=
? ?
??
+ ? ? ??
?? ? ?
For maximum Coulomb’s force for x
0
dF
dx
=
On solving
22
d
x =
4. The speed of light in media ‘A’ and ‘B’ are
2.0 × 10
10
cm/s and 1.5 × 10
10
cm/s respectively. A
ray of light enters from the medium B to A at an
incident angle ‘?’. If the ray suffers total internal
reflection, then
(A)
1
3
sin
4
-
??
?=
??
??
(B)
1
2
sin
3
-
? ?
?>
? ?
? ?
(C)
1
3
sin
4
-
??
?<
??
??
(D)
1
3
sin
4
-
??
?>
??
??
Answer (D)
Sol.
8
8
3 10
1.5
2 10
A
×
µ= =
×
8
8
3 10
2
1.5 10
B
×
µ= =
×
For TIR
? > i c
1
1.5
sin
2
-
??
?>
??
??
1
3
sin
4
-
??
?>
??
??
5. In the following nuclear reaction,
1 2 34
-
aß a ?
?? ? ?? ? ? ?? ? ?? ? DD D D D
Mass number of D is 182 and atomic number is 74.
Mass number and atomic number of D4 respectively
will be _____
(A) 174 and 71
(B) 174 and 69
(C) 172 and 69
(D) 172 and 71
Answer (A)
Sol. Equivalent reaction can be written as
D ?? D4 + 2a + ß
–
+ ?
? Mass number of D4 = Mass number of D – 2 × 4
= 182 – 8 = 174
? Atomic number of D4
= Atomic number of D – 2 × 2 + 1
= 74 – 4 + 1 = 71
6. The electric field at a point associated with a light
wave is given by
E = 200[sin(6 × 10
15
)t + sin(9 × 10
15
)t] Vm
–1
Given : h = 4.14 × 10
–15
eVs
If this light falls on a metal surface having a work
function of 2.50 eV, the maximum kinetic energy of
the photoelectrons will be
(A) 1.90 eV
(B) 3.27 eV
(C) 3.60 eV
(D) 3.42 eV
Answer (D)
Sol. Frequency of EM waves =
15
6
10
2
×
p
and
15
9
10
2
×
p
Energy of one photon of these waves
15 15
6
eV 4.14 10 10
2
-
? ?
= × ××
? ?
p ? ?
and
15 15
9
eV 4.14 10 10
2
-
? ?
× ××
? ?
p ? ?
= 3.95 eV and 5.93 eV
? Energy of maximum energetic electrons
= 5.93 – 2.50 = 3.43 eV
7. A capacitor is discharging through a resistor R.
Consider in time t1, the energy stored in the
capacitor reduces to half of its initial value and in
time t2, the charge stored reduces to one eighth of
its initial value. The ratio
1
2
t
t
will be
(A)
1
2
(B)
1
3
(C)
1
4
(D)
1
6
Answer (D)
Sol. For a discharging capacitor when energy reduces
to half the charge would become
1
2
times the
initial value.
?
1
1/2
/
1
2
t
e
-t ? ?
=
? ?
? ?
Similarly,
2
3
/
1
2
t
e
-t ? ?
=
? ?
? ?
?
1
2
1
6
t
t
=
8. Starting with the same initial conditions, an ideal
gas expands from volume V1 to V2 in three different
ways. The work done by the gas is W1 if the process
is purely isothermal, W2, if the process is purely
adiabatic and W3 if the process is purely isobaric.
Then, choose the correct option.
(A) W1 < W2 < W3
(B) W2 < W3 < W1
(C) W3 < W1 < W2
(D) W2 < W1 < W3
Answer (D)
Sol.
Comparing the area under the PV graph
A3 > A1 > A2
? W3 > W1 > W2
9. Two long current carrying conductors are placed
parallel to each other at a distance of 8 cm between
them. The magnitude of magnetic field produced at
mid-point between the two conductors due to
current flowing in them is 30 µT. The equal current
flowing in the two conductors is:
(A) 30 A in the same direction
(B) 30 A in the opposite direction
(C) 60 A in the opposite direction
(D) 300 A in the opposite direction
Answer (B)
Sol. As Bnet ? 0 that is the wires are carrying current in
opposite direction.
6 0
2
2
30 10 T
2 (4 10 )
I
-
-
µ×
= ×
p×
?
6
6
30 10
A
10
I
-
-
×
= = 30 A in opposite direction.
10. The time period of a satellite revolving around earth
in a given orbit is 7 hours. If the radius of orbit is
increased to three times its previous value, then
approximate new time period of the satellite will be
(A) 40 hours (B) 36 hours
(C) 30 hours (D) 25 hours
Answer (B)
Sol.
3
2 22
21
1
R
TT
R
??
=
??
??
? ( )
3/2
2
7 5.2 7
3
T= ט ×
2
36 hrs T ?
11. The TV transmission tower at a particular station
has a height of 125 m. For doubling the coverage
of its range, the height of the tower should be
increased by
(A) 125 m (B) 250 m
(C) 375 m (D) 500 m
Answer (C)
Sol. Range 2 Re = Rh
Let the height be h' to double the range so
2 2 Re ' = Rh
On solving h' = 4h
h' = 500 m
So ?h = 375 m
12. The motion of a simple pendulum executing S.H.M.
is represented by the following equation.
y = A sin(pt + f), where time is measured in second.
The length of pendulum is
(A) 97.23 cm (B) 25.3 cm
(C) 99.4 cm (D) 406.1 cm
Answer (C)
Sol. ?= p =
?
g
So
2
=
p
?
g
? 99.4 cm (Nearest value)
13. A vessel contains 16 g of hydrogen and 128 g of
oxygen at standard temperature and pressure. The
volume of the vessel in cm
3
is:
(A) 72 × 10
5
(B) 32 × 10
5
(C) 27 × 10
4
(D) 54 × 10
4
Answer (C)
Sol. Total number of moles are
22
HO
nn n = +
16 128
2 32
= +
= 12 moles
Using PV = nRT
=
nRT
V
P
3
5
12 8.31 273.15
m
10
××
=
= 0.27 m
3
= 27 × 10
4
cm
3
14. Given below are two statements:
Statement I: The electric force changes the speed
of the charged particle and hence changes its
kinetic energy; whereas the magnetic force does
not change the kinetic energy of the charged
particle.
Statement II: The electric force accelerates the
positively charged particle perpendicular to the
direction of electric field. The magnetic force
accelerates the moving charged particle along the
direction of magnetic field.
In the light of the above statements, choose the
most appropriate answer from the options given
below:
(A) Both statement I and statement II are correct
(B) Both statement I and statement II are incorrect
(C) Statement I is correct but statement II is
incorrect
(D) Statement I is incorrect but statement II is
correct
Answer (C)
Sol. Electric field accelerates the particle in the direction
of field
( )
= =
??
?
F qE maand magnetic field
accelerates the particle perpendicular to the field
( )
= ×=
??
? ?
F qv B ma
15. A block of mass 40 kg slides over a surface, when
a mass of 4 kg is suspended through an
inextensible massless string passing over
frictionless pulley as shown below.
The coefficient of kinetic friction between the
surface and block is 0.02. The acceleration of block
is (Given g = 10 ms
–2
.)
(A) 1 ms
–2
(B) 1/5 ms
–2
(C) 4/5 ms
–2
(D) 8/11 ms
–2
Answer (D)
Sol.
max
N = µ
r
f
= 0.02 × 400
= 8 N
Let the acceleration is a as shown then.
40 – T = 4a
T – 8 = 40a
?
2
32 8
m/s
44 11
= = a
16. In the given figure, the block of mass m is dropped
from the point ‘A’. The expression for kinetic energy
of block when it reaches point ‘B’ is
(A)
2
0
1
2
mgy (B)
2
1
2
mgy
(C) mg(y – y0) (D) mgy0
Answer (D)
Sol. Loss is potential energy = gain in kinetic energy
– (mg(y – y0) – mgy) = KE – 0
? KE = mgy0
17. A block of mass M placed inside a box descends
vertically with acceleration ‘a’. The block exerts a
force equal to one-fourth of its weight on the floor of
the box.
The value of ‘a’ will be
(A)
4
g
(B)
2
g
(C)
3
4
g
(D) g
Answer (C)
Sol.
Using Newton’s second law
4
mg
mg ma -=
?
3
4
g
a =
18. If the electric potential at any point (x, y, z)m in
space is given by V = 3x
2
volt.
The electric field at the point (1, 0, 3)m will be
(A) 3 Vm
–1
, directed along positive x-axis
(B) 3 Vm
–1
, directed along negative x-axis
(C) 6 Vm
–1
, directed along positive x-axis
(D) 6 Vm
–1
, directed along negative x-axis
Answer (D)
Sol.
ˆ
dV
Ei
dx
= -
?
ˆ
6 E xi = -
?
So, E
?
at (1, 0, 3) is
ˆ
6 Vm Ei = -
?
19. The combination of two identical cells, whether
connected in series or parallel combination
provides the same current through an external
resistance of 2 ?. The value of internal resistance
of each cell is
(A) 2 ? (B) 4 ?
(C) 6 ? (D) 8 ?
Answer (A)
Sol.
From diagram
2
2
p
E
i
r
=
+
and
2
22
s
E
i
r
=
+
given i p = i s
11
1
2
2
r
r
=
+
+
12
2
r
r += +
r = 2 ?
20. A person can throw a ball upto a maximum range
of 100 m. How high above the ground he can throw
the same ball?
(A) 25 m (B) 50 m
(C) 100 m (D) 200 m
Answer (B)
Sol.
2
max
100 m
u
R
g
= =
So,
2
max
50 m
2
u
H
g
= =
SECTION - B
Numerical Value Type Questions: This section
contains 10 questions. In Section B, attempt any five
questions out of 10. The answer to each question is a
NUMERICAL VALUE. For each question, enter the
correct numerical value (in decimal notation,
truncated/rounded-off to the second decimal place; e.g.
06.25, 07.00, –00.33, –00.30, 30.27, –27.30) using the
mouse and the on-screen virtual numeric keypad in the
place designated to enter the answer.
1. The vernier constant of Vernier callipers is 0.1 mm
and it has zero error of (–0.05) cm. While measuring
diameter of a sphere, the main scale reading is
1.7 cm and coinciding vernier division is 5. The
corrected diameter will be ________× 10
–2
cm.
Answer (180)
Sol. Since zero error is negative, we will add 0.05 cm.
? Corrected reading = 1.7 cm + 5 × 0.1 mm + 0.05 cm
= 180 × 10
–2
cm
2. A small spherical ball of radius 0.1 mm and density
10
4
kg m
–3
falls freely under gravity through a
distance h before entering a tank of water. If, after
entering the water the velocity of ball does not
change and it continue to fall with same constant
velocity inside water, then the value of h will be
______ m.
(Given g = 10 ms
–2
, viscosity of water = 1.0 × 10
–5
N-sm
–2
).
Answer (20)
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