Page 1
1
FINAL JEE –MAIN EXAMINATION – JULY, 2022
(Held On Wednesday 27
th
July, 2022) TIME : 3 : 00 PM to 6 : 00 PM
PHYSICS TEST PAPER WITH SOLUTION
SECTION-A
1. An expression of energy density is given by
?? ??
?
??
?? ?
x
u sin
kt
, where ?, ? are constants, x is
displacement, k is Boltzmann constant and t is the
temperature. The dimensions of ? will be :
(A) ?
2 –2 –1
[ML T ] (B)
0 2 –2
[M L T ]
(C)
0 0 0
[M L T ] (D)
0 2 0
[M L T ]
Official Ans. by NTA (D)
Sol.
?
?
?
0 0 0
22
[L]
[M L T ]
[M L T ]
?
??
12
[ML T ]
??
?
?
? ? ? ?
?
2 2 1 2 3
3 2 2
[M L T ] [M L T ][L ]
[L ] M L T
2. A body of mass 10 kg is projected at an angle of
45° with the horizontal. The trajectory of the body
is observed to pass through a point (20, 10). If T is
the time of flight, then its momentum vector, at
time ?
T
t
2
, is _________
[Take g = 10 m/s
2
]
(A) ?
ˆˆ
100i (100 2 – 200)j
(B) ?
ˆˆ
100 2 i (100 – 200 2)j
(C) ?
ˆˆ
100 i (100 – 200 2)j
(D) ?
ˆˆ
100 2 i (100 2 – 200)j
Official Ans. by NTA (D)
Sol.
u = 20
??
(2)(20)
T 2 2
2 (10)
?
? ? ?
ˆˆ
v 10 2 i (10 2 10(2)] j
Momentum
??
? ? ? ?
ˆˆ
p M v 100 2 i (100 2 200) j
3. A block of mass M slides down on a rough
inclined plane with constant velocity. The angle
made by the incline plane with horizontal is ?. The
magnitude of the contact force will be :
(A) Mg
(B) Mg cos ?
(C) ? ? ? Mgsin Mgcos
(D) ? ? ? Mgsin 1
Official Ans. by NTA (A)
Sol.
N = Mgcos ?
f = Mgsin ?
22
R N f ??
R = Mg
? ? ? ? ?
??
??
??
2
2
2
10x (10)(100)
y x 10 20
1
u
2u
2
Page 2
1
FINAL JEE –MAIN EXAMINATION – JULY, 2022
(Held On Wednesday 27
th
July, 2022) TIME : 3 : 00 PM to 6 : 00 PM
PHYSICS TEST PAPER WITH SOLUTION
SECTION-A
1. An expression of energy density is given by
?? ??
?
??
?? ?
x
u sin
kt
, where ?, ? are constants, x is
displacement, k is Boltzmann constant and t is the
temperature. The dimensions of ? will be :
(A) ?
2 –2 –1
[ML T ] (B)
0 2 –2
[M L T ]
(C)
0 0 0
[M L T ] (D)
0 2 0
[M L T ]
Official Ans. by NTA (D)
Sol.
?
?
?
0 0 0
22
[L]
[M L T ]
[M L T ]
?
??
12
[ML T ]
??
?
?
? ? ? ?
?
2 2 1 2 3
3 2 2
[M L T ] [M L T ][L ]
[L ] M L T
2. A body of mass 10 kg is projected at an angle of
45° with the horizontal. The trajectory of the body
is observed to pass through a point (20, 10). If T is
the time of flight, then its momentum vector, at
time ?
T
t
2
, is _________
[Take g = 10 m/s
2
]
(A) ?
ˆˆ
100i (100 2 – 200)j
(B) ?
ˆˆ
100 2 i (100 – 200 2)j
(C) ?
ˆˆ
100 i (100 – 200 2)j
(D) ?
ˆˆ
100 2 i (100 2 – 200)j
Official Ans. by NTA (D)
Sol.
u = 20
??
(2)(20)
T 2 2
2 (10)
?
? ? ?
ˆˆ
v 10 2 i (10 2 10(2)] j
Momentum
??
? ? ? ?
ˆˆ
p M v 100 2 i (100 2 200) j
3. A block of mass M slides down on a rough
inclined plane with constant velocity. The angle
made by the incline plane with horizontal is ?. The
magnitude of the contact force will be :
(A) Mg
(B) Mg cos ?
(C) ? ? ? Mgsin Mgcos
(D) ? ? ? Mgsin 1
Official Ans. by NTA (A)
Sol.
N = Mgcos ?
f = Mgsin ?
22
R N f ??
R = Mg
? ? ? ? ?
??
??
??
2
2
2
10x (10)(100)
y x 10 20
1
u
2u
2
2
4. A block ‘A’ takes 2 s to slide down a frictionless
incline of 30° and length ‘l’, kept inside a lift going
up with uniform velocity ‘v’. If the incline is
changed to 45°, the time taken by the block, to
slide down the incline, will be approximately:
(A) 2.66 s (B) 0.83 s
(C) 1.68 s (D) 0.70 s
Official Ans. by NTA (C)
Sol.
a = g sin ?
??
2
1
gsin30 (2)
2
….(1)
??
2
1
gsin 45 t
2
….(2)
??
? ? ?
??
??
2
1 1
(4) t t 2 2 1.68
2 2
5. The velocity of the bullet becomes one third after it
penetrates 4 cm in a wooden block. Assuming that
bullet is facing a constant resistance during its
motion in the block. The bullet stops completely
after travelling at (4 + x) cm inside the block. The
value of x is:
(A) 2.0 (B) 1.0
(C) 0. 5 (D) 1.5
Official Ans. by NTA (C)
Sol.
??
? ? ? ? ?
??
??
2 22
2
8V V V
V 2a(4) a
9(8) 9 3
? ? ?
2
0 V 2a(4 x)
? ?
??
??
??
??
2
2 V
V 2 (4 x)
9
4.5 = 4 + x
x = 0.5 ?
6. A body of mass m is projected with velocity ?
e
v in
vertically upward direction from the surface of the
earth into space. It is given that
e
v is escape
velocity and ? < 1. If air resistance is considered to
the negligible, then the maximum height from the
centre of earth, to which the body can go, will be
(R : radius of earth)
(A)
??
2
R
1
(B)
?
2
R
1–
(C)
?
R
1–
(D)
?
?
2
2
R
1–
Official Ans. by NTA (B)
Sol.
22
e
GMm 1 GMm
mV
R 2 h
? ? ? ? ?
2
GMm 1 2GMm GMm
R 2 R h
? ? ? ? ?
2
11
R R h
??
??
2
11
hR
??
?
2
R
h
1
?
??
Page 3
1
FINAL JEE –MAIN EXAMINATION – JULY, 2022
(Held On Wednesday 27
th
July, 2022) TIME : 3 : 00 PM to 6 : 00 PM
PHYSICS TEST PAPER WITH SOLUTION
SECTION-A
1. An expression of energy density is given by
?? ??
?
??
?? ?
x
u sin
kt
, where ?, ? are constants, x is
displacement, k is Boltzmann constant and t is the
temperature. The dimensions of ? will be :
(A) ?
2 –2 –1
[ML T ] (B)
0 2 –2
[M L T ]
(C)
0 0 0
[M L T ] (D)
0 2 0
[M L T ]
Official Ans. by NTA (D)
Sol.
?
?
?
0 0 0
22
[L]
[M L T ]
[M L T ]
?
??
12
[ML T ]
??
?
?
? ? ? ?
?
2 2 1 2 3
3 2 2
[M L T ] [M L T ][L ]
[L ] M L T
2. A body of mass 10 kg is projected at an angle of
45° with the horizontal. The trajectory of the body
is observed to pass through a point (20, 10). If T is
the time of flight, then its momentum vector, at
time ?
T
t
2
, is _________
[Take g = 10 m/s
2
]
(A) ?
ˆˆ
100i (100 2 – 200)j
(B) ?
ˆˆ
100 2 i (100 – 200 2)j
(C) ?
ˆˆ
100 i (100 – 200 2)j
(D) ?
ˆˆ
100 2 i (100 2 – 200)j
Official Ans. by NTA (D)
Sol.
u = 20
??
(2)(20)
T 2 2
2 (10)
?
? ? ?
ˆˆ
v 10 2 i (10 2 10(2)] j
Momentum
??
? ? ? ?
ˆˆ
p M v 100 2 i (100 2 200) j
3. A block of mass M slides down on a rough
inclined plane with constant velocity. The angle
made by the incline plane with horizontal is ?. The
magnitude of the contact force will be :
(A) Mg
(B) Mg cos ?
(C) ? ? ? Mgsin Mgcos
(D) ? ? ? Mgsin 1
Official Ans. by NTA (A)
Sol.
N = Mgcos ?
f = Mgsin ?
22
R N f ??
R = Mg
? ? ? ? ?
??
??
??
2
2
2
10x (10)(100)
y x 10 20
1
u
2u
2
2
4. A block ‘A’ takes 2 s to slide down a frictionless
incline of 30° and length ‘l’, kept inside a lift going
up with uniform velocity ‘v’. If the incline is
changed to 45°, the time taken by the block, to
slide down the incline, will be approximately:
(A) 2.66 s (B) 0.83 s
(C) 1.68 s (D) 0.70 s
Official Ans. by NTA (C)
Sol.
a = g sin ?
??
2
1
gsin30 (2)
2
….(1)
??
2
1
gsin 45 t
2
….(2)
??
? ? ?
??
??
2
1 1
(4) t t 2 2 1.68
2 2
5. The velocity of the bullet becomes one third after it
penetrates 4 cm in a wooden block. Assuming that
bullet is facing a constant resistance during its
motion in the block. The bullet stops completely
after travelling at (4 + x) cm inside the block. The
value of x is:
(A) 2.0 (B) 1.0
(C) 0. 5 (D) 1.5
Official Ans. by NTA (C)
Sol.
??
? ? ? ? ?
??
??
2 22
2
8V V V
V 2a(4) a
9(8) 9 3
? ? ?
2
0 V 2a(4 x)
? ?
??
??
??
??
2
2 V
V 2 (4 x)
9
4.5 = 4 + x
x = 0.5 ?
6. A body of mass m is projected with velocity ?
e
v in
vertically upward direction from the surface of the
earth into space. It is given that
e
v is escape
velocity and ? < 1. If air resistance is considered to
the negligible, then the maximum height from the
centre of earth, to which the body can go, will be
(R : radius of earth)
(A)
??
2
R
1
(B)
?
2
R
1–
(C)
?
R
1–
(D)
?
?
2
2
R
1–
Official Ans. by NTA (B)
Sol.
22
e
GMm 1 GMm
mV
R 2 h
? ? ? ? ?
2
GMm 1 2GMm GMm
R 2 R h
? ? ? ? ?
2
11
R R h
??
??
2
11
hR
??
?
2
R
h
1
?
??
3
?
7. A steel wire of length 3.2 m (Y
S
= 2.0 × 10
11
Nm
–2
)
and a copper wire of length 4.4 M
(Y
C
= 1.1 × 10
11
Nm
–2
), both of radius 1.4 mm are
connected end to end. When stretched by a load,
the net elongation is found to be 1.4 mm. The load
applied, in Newton, will be: (Given ??
22
7
)
(A) 360 (B) 180 (C) 1080 (D) 154
Official Ans. by NTA (D)
Sol.
? ?
1
+ ? ?
2
= ? ?
? ? ?
12
1 1 2 2
FF
A y A y
2
12
1 1 2 2
F 1.54 10 154
A y A y
?
? ? ? ?
?
8. In 1
st
case, Carnot engine operates between
temperatures 300 K and 100 K. In 2
nd
case, as
shown in the figure, a combination of two engines
is used. The efficiency of this combination (in 2
nd
case) will be :
(A) same as the 1
st
case
(B) always greater than the 1
st
case
(C) always less than the 1
st
case
(D) may increase or decrease with respect to the 1
st
case
Official Ans. by NTA (C)
Sol. First case : ? ? ? ?
100 2
1
300 3
Second case : ?
net
= ?
1
+ ?
2
– ?
1
?
2
? ? ? ?
1
200 1
1
300 3
? ? ? ?
2
100 1
1
200 2
net
1 1 1 2
3 2 6 3
? ? ? ? ?
? (first case) = ? (second case)
9. Which statements are correct about degrees of
freedom?
A. A molecule with n degrees of freedom has n
2
different ways of storing energy.
B. Each degree of freedom is associated with
1
RT
2
average energy per mole.
C. A monoatomic gas molecule has 1 rotational
degree of freedom where as diatomic molecule
has 2 rotational degrees of freedom
D. CH
4
has a total to 6 degrees of freedom
Choose the correct answer from the option
given below:
(A) B and C only (B) B and D only
(C) A and B only (D) C and D only
Official Ans. by NTA (B)
Sol. Methane molecule is tetrahedron
Degree of freedom due to rotation = 3
Degree of freedom due to translation = 3
10. A charge of 4 ?C is to be divided into two. The
distance between the two divided charges is
constant. The magnitude of the divided charges so
that the force between them is maximum, will be:
(A) 1 ?C and 3 ?C (B) 2 ?C and 2 ?C
(C) 0 and 4 ?C (D) 1.5 ?C and 2.5 ?C
Official Ans. by NTA (B)
Sol.
?
?
2
Kq(4 q)
F
d
? ? ?
2
dF K
[4 2q] 0
dq
d
q = 2
Page 4
1
FINAL JEE –MAIN EXAMINATION – JULY, 2022
(Held On Wednesday 27
th
July, 2022) TIME : 3 : 00 PM to 6 : 00 PM
PHYSICS TEST PAPER WITH SOLUTION
SECTION-A
1. An expression of energy density is given by
?? ??
?
??
?? ?
x
u sin
kt
, where ?, ? are constants, x is
displacement, k is Boltzmann constant and t is the
temperature. The dimensions of ? will be :
(A) ?
2 –2 –1
[ML T ] (B)
0 2 –2
[M L T ]
(C)
0 0 0
[M L T ] (D)
0 2 0
[M L T ]
Official Ans. by NTA (D)
Sol.
?
?
?
0 0 0
22
[L]
[M L T ]
[M L T ]
?
??
12
[ML T ]
??
?
?
? ? ? ?
?
2 2 1 2 3
3 2 2
[M L T ] [M L T ][L ]
[L ] M L T
2. A body of mass 10 kg is projected at an angle of
45° with the horizontal. The trajectory of the body
is observed to pass through a point (20, 10). If T is
the time of flight, then its momentum vector, at
time ?
T
t
2
, is _________
[Take g = 10 m/s
2
]
(A) ?
ˆˆ
100i (100 2 – 200)j
(B) ?
ˆˆ
100 2 i (100 – 200 2)j
(C) ?
ˆˆ
100 i (100 – 200 2)j
(D) ?
ˆˆ
100 2 i (100 2 – 200)j
Official Ans. by NTA (D)
Sol.
u = 20
??
(2)(20)
T 2 2
2 (10)
?
? ? ?
ˆˆ
v 10 2 i (10 2 10(2)] j
Momentum
??
? ? ? ?
ˆˆ
p M v 100 2 i (100 2 200) j
3. A block of mass M slides down on a rough
inclined plane with constant velocity. The angle
made by the incline plane with horizontal is ?. The
magnitude of the contact force will be :
(A) Mg
(B) Mg cos ?
(C) ? ? ? Mgsin Mgcos
(D) ? ? ? Mgsin 1
Official Ans. by NTA (A)
Sol.
N = Mgcos ?
f = Mgsin ?
22
R N f ??
R = Mg
? ? ? ? ?
??
??
??
2
2
2
10x (10)(100)
y x 10 20
1
u
2u
2
2
4. A block ‘A’ takes 2 s to slide down a frictionless
incline of 30° and length ‘l’, kept inside a lift going
up with uniform velocity ‘v’. If the incline is
changed to 45°, the time taken by the block, to
slide down the incline, will be approximately:
(A) 2.66 s (B) 0.83 s
(C) 1.68 s (D) 0.70 s
Official Ans. by NTA (C)
Sol.
a = g sin ?
??
2
1
gsin30 (2)
2
….(1)
??
2
1
gsin 45 t
2
….(2)
??
? ? ?
??
??
2
1 1
(4) t t 2 2 1.68
2 2
5. The velocity of the bullet becomes one third after it
penetrates 4 cm in a wooden block. Assuming that
bullet is facing a constant resistance during its
motion in the block. The bullet stops completely
after travelling at (4 + x) cm inside the block. The
value of x is:
(A) 2.0 (B) 1.0
(C) 0. 5 (D) 1.5
Official Ans. by NTA (C)
Sol.
??
? ? ? ? ?
??
??
2 22
2
8V V V
V 2a(4) a
9(8) 9 3
? ? ?
2
0 V 2a(4 x)
? ?
??
??
??
??
2
2 V
V 2 (4 x)
9
4.5 = 4 + x
x = 0.5 ?
6. A body of mass m is projected with velocity ?
e
v in
vertically upward direction from the surface of the
earth into space. It is given that
e
v is escape
velocity and ? < 1. If air resistance is considered to
the negligible, then the maximum height from the
centre of earth, to which the body can go, will be
(R : radius of earth)
(A)
??
2
R
1
(B)
?
2
R
1–
(C)
?
R
1–
(D)
?
?
2
2
R
1–
Official Ans. by NTA (B)
Sol.
22
e
GMm 1 GMm
mV
R 2 h
? ? ? ? ?
2
GMm 1 2GMm GMm
R 2 R h
? ? ? ? ?
2
11
R R h
??
??
2
11
hR
??
?
2
R
h
1
?
??
3
?
7. A steel wire of length 3.2 m (Y
S
= 2.0 × 10
11
Nm
–2
)
and a copper wire of length 4.4 M
(Y
C
= 1.1 × 10
11
Nm
–2
), both of radius 1.4 mm are
connected end to end. When stretched by a load,
the net elongation is found to be 1.4 mm. The load
applied, in Newton, will be: (Given ??
22
7
)
(A) 360 (B) 180 (C) 1080 (D) 154
Official Ans. by NTA (D)
Sol.
? ?
1
+ ? ?
2
= ? ?
? ? ?
12
1 1 2 2
FF
A y A y
2
12
1 1 2 2
F 1.54 10 154
A y A y
?
? ? ? ?
?
8. In 1
st
case, Carnot engine operates between
temperatures 300 K and 100 K. In 2
nd
case, as
shown in the figure, a combination of two engines
is used. The efficiency of this combination (in 2
nd
case) will be :
(A) same as the 1
st
case
(B) always greater than the 1
st
case
(C) always less than the 1
st
case
(D) may increase or decrease with respect to the 1
st
case
Official Ans. by NTA (C)
Sol. First case : ? ? ? ?
100 2
1
300 3
Second case : ?
net
= ?
1
+ ?
2
– ?
1
?
2
? ? ? ?
1
200 1
1
300 3
? ? ? ?
2
100 1
1
200 2
net
1 1 1 2
3 2 6 3
? ? ? ? ?
? (first case) = ? (second case)
9. Which statements are correct about degrees of
freedom?
A. A molecule with n degrees of freedom has n
2
different ways of storing energy.
B. Each degree of freedom is associated with
1
RT
2
average energy per mole.
C. A monoatomic gas molecule has 1 rotational
degree of freedom where as diatomic molecule
has 2 rotational degrees of freedom
D. CH
4
has a total to 6 degrees of freedom
Choose the correct answer from the option
given below:
(A) B and C only (B) B and D only
(C) A and B only (D) C and D only
Official Ans. by NTA (B)
Sol. Methane molecule is tetrahedron
Degree of freedom due to rotation = 3
Degree of freedom due to translation = 3
10. A charge of 4 ?C is to be divided into two. The
distance between the two divided charges is
constant. The magnitude of the divided charges so
that the force between them is maximum, will be:
(A) 1 ?C and 3 ?C (B) 2 ?C and 2 ?C
(C) 0 and 4 ?C (D) 1.5 ?C and 2.5 ?C
Official Ans. by NTA (B)
Sol.
?
?
2
Kq(4 q)
F
d
? ? ?
2
dF K
[4 2q] 0
dq
d
q = 2
4
11. A. The drift velocity of electrons decreases with
the increase in the temperature of conductor.
B. The drift velocity is inversely proportional to
the area of cross-section of given conductor.
C. The drift velocity does not depend on the
applied potential difference to the conductor.
D. The drift velocity of electron is inversely
proportional to the length of the conductor.
E. The drift velocity increases with the increase in
the temperature of conductor.
Choose the correct answer from the options given
below:
(A) A and B only (B) A and D only
(C) B and E only (D) B and C only
Official Ans. by NTA (B)
Sol. Drift velocity =
? ??
??
??
e
E
m
d
eV
v
m
?? ? ? ? ?
?
? ? ? ?
? ? ? ?
?V = Potential difference applied across the wire
As temperature increases, relaxation time
decreases, hence V
d
decreases.
As per formula, ?
d
1
V
d
I
v
neA
? , as it is not mentioned that current is at
steady state neither it is mentioned that n is
constant for given conductor. So it can't be said
that v
d
is inversely proportional to A.
I = neAv
d
=
VV
A
R
?
?
d
V
v
ne
?
?
V
E
??
?
??
??
d
eE
v
m
?
?
? decrease with temperature increase.
First and fourth statements are correct.
12. A compass needle of oscillation magnetometer
oscillates 20 times per minute at a place P of dip
30°. The number of oscillations per minute become
10 at another place Q of 60° dip. The ratio of the
total magnetic field at the two places (B
Q
: B
P
) is:
(A) 3 : 4 (B) 4: 3
(C) 3 :2 (D) 2: 3
Official Ans. by NTA (A)
Sol. ??
H
I
T2
BM
1
P
I
T 3sec 2
(B cos30 )M
? ? ?
?
2
Q
I
T 6sec 2
(B cos60 )M
? ? ?
?
? ?
Q
P
31
B / 2
6
3
B
2
??
??
??
??
??
Q
P
B
3
6
3B
??
?
??
??
??
Q
P
B
3
4B
?
QP
B : B 3 : 4 ?
13. A cyclotron is used to accelerate protons. If the
operating magnetic field is 1.0 T and the radius of
the cyclotron 'dees' is 60 cm, the kinetic energy of
the accelerated protons in MeV will be :
[use m
p
= 1.6 × 10
–27
kg, e = 1.6 × 10
–19
C]
(A) 12 (B) 18
(C) 16 (D) 32
Official Ans. by NTA (B)
Sol. Kinetic energy of electron in cyclotron
=
??
??
??
??
2 2 2
0
q B r
2m
= 18 MeV
Page 5
1
FINAL JEE –MAIN EXAMINATION – JULY, 2022
(Held On Wednesday 27
th
July, 2022) TIME : 3 : 00 PM to 6 : 00 PM
PHYSICS TEST PAPER WITH SOLUTION
SECTION-A
1. An expression of energy density is given by
?? ??
?
??
?? ?
x
u sin
kt
, where ?, ? are constants, x is
displacement, k is Boltzmann constant and t is the
temperature. The dimensions of ? will be :
(A) ?
2 –2 –1
[ML T ] (B)
0 2 –2
[M L T ]
(C)
0 0 0
[M L T ] (D)
0 2 0
[M L T ]
Official Ans. by NTA (D)
Sol.
?
?
?
0 0 0
22
[L]
[M L T ]
[M L T ]
?
??
12
[ML T ]
??
?
?
? ? ? ?
?
2 2 1 2 3
3 2 2
[M L T ] [M L T ][L ]
[L ] M L T
2. A body of mass 10 kg is projected at an angle of
45° with the horizontal. The trajectory of the body
is observed to pass through a point (20, 10). If T is
the time of flight, then its momentum vector, at
time ?
T
t
2
, is _________
[Take g = 10 m/s
2
]
(A) ?
ˆˆ
100i (100 2 – 200)j
(B) ?
ˆˆ
100 2 i (100 – 200 2)j
(C) ?
ˆˆ
100 i (100 – 200 2)j
(D) ?
ˆˆ
100 2 i (100 2 – 200)j
Official Ans. by NTA (D)
Sol.
u = 20
??
(2)(20)
T 2 2
2 (10)
?
? ? ?
ˆˆ
v 10 2 i (10 2 10(2)] j
Momentum
??
? ? ? ?
ˆˆ
p M v 100 2 i (100 2 200) j
3. A block of mass M slides down on a rough
inclined plane with constant velocity. The angle
made by the incline plane with horizontal is ?. The
magnitude of the contact force will be :
(A) Mg
(B) Mg cos ?
(C) ? ? ? Mgsin Mgcos
(D) ? ? ? Mgsin 1
Official Ans. by NTA (A)
Sol.
N = Mgcos ?
f = Mgsin ?
22
R N f ??
R = Mg
? ? ? ? ?
??
??
??
2
2
2
10x (10)(100)
y x 10 20
1
u
2u
2
2
4. A block ‘A’ takes 2 s to slide down a frictionless
incline of 30° and length ‘l’, kept inside a lift going
up with uniform velocity ‘v’. If the incline is
changed to 45°, the time taken by the block, to
slide down the incline, will be approximately:
(A) 2.66 s (B) 0.83 s
(C) 1.68 s (D) 0.70 s
Official Ans. by NTA (C)
Sol.
a = g sin ?
??
2
1
gsin30 (2)
2
….(1)
??
2
1
gsin 45 t
2
….(2)
??
? ? ?
??
??
2
1 1
(4) t t 2 2 1.68
2 2
5. The velocity of the bullet becomes one third after it
penetrates 4 cm in a wooden block. Assuming that
bullet is facing a constant resistance during its
motion in the block. The bullet stops completely
after travelling at (4 + x) cm inside the block. The
value of x is:
(A) 2.0 (B) 1.0
(C) 0. 5 (D) 1.5
Official Ans. by NTA (C)
Sol.
??
? ? ? ? ?
??
??
2 22
2
8V V V
V 2a(4) a
9(8) 9 3
? ? ?
2
0 V 2a(4 x)
? ?
??
??
??
??
2
2 V
V 2 (4 x)
9
4.5 = 4 + x
x = 0.5 ?
6. A body of mass m is projected with velocity ?
e
v in
vertically upward direction from the surface of the
earth into space. It is given that
e
v is escape
velocity and ? < 1. If air resistance is considered to
the negligible, then the maximum height from the
centre of earth, to which the body can go, will be
(R : radius of earth)
(A)
??
2
R
1
(B)
?
2
R
1–
(C)
?
R
1–
(D)
?
?
2
2
R
1–
Official Ans. by NTA (B)
Sol.
22
e
GMm 1 GMm
mV
R 2 h
? ? ? ? ?
2
GMm 1 2GMm GMm
R 2 R h
? ? ? ? ?
2
11
R R h
??
??
2
11
hR
??
?
2
R
h
1
?
??
3
?
7. A steel wire of length 3.2 m (Y
S
= 2.0 × 10
11
Nm
–2
)
and a copper wire of length 4.4 M
(Y
C
= 1.1 × 10
11
Nm
–2
), both of radius 1.4 mm are
connected end to end. When stretched by a load,
the net elongation is found to be 1.4 mm. The load
applied, in Newton, will be: (Given ??
22
7
)
(A) 360 (B) 180 (C) 1080 (D) 154
Official Ans. by NTA (D)
Sol.
? ?
1
+ ? ?
2
= ? ?
? ? ?
12
1 1 2 2
FF
A y A y
2
12
1 1 2 2
F 1.54 10 154
A y A y
?
? ? ? ?
?
8. In 1
st
case, Carnot engine operates between
temperatures 300 K and 100 K. In 2
nd
case, as
shown in the figure, a combination of two engines
is used. The efficiency of this combination (in 2
nd
case) will be :
(A) same as the 1
st
case
(B) always greater than the 1
st
case
(C) always less than the 1
st
case
(D) may increase or decrease with respect to the 1
st
case
Official Ans. by NTA (C)
Sol. First case : ? ? ? ?
100 2
1
300 3
Second case : ?
net
= ?
1
+ ?
2
– ?
1
?
2
? ? ? ?
1
200 1
1
300 3
? ? ? ?
2
100 1
1
200 2
net
1 1 1 2
3 2 6 3
? ? ? ? ?
? (first case) = ? (second case)
9. Which statements are correct about degrees of
freedom?
A. A molecule with n degrees of freedom has n
2
different ways of storing energy.
B. Each degree of freedom is associated with
1
RT
2
average energy per mole.
C. A monoatomic gas molecule has 1 rotational
degree of freedom where as diatomic molecule
has 2 rotational degrees of freedom
D. CH
4
has a total to 6 degrees of freedom
Choose the correct answer from the option
given below:
(A) B and C only (B) B and D only
(C) A and B only (D) C and D only
Official Ans. by NTA (B)
Sol. Methane molecule is tetrahedron
Degree of freedom due to rotation = 3
Degree of freedom due to translation = 3
10. A charge of 4 ?C is to be divided into two. The
distance between the two divided charges is
constant. The magnitude of the divided charges so
that the force between them is maximum, will be:
(A) 1 ?C and 3 ?C (B) 2 ?C and 2 ?C
(C) 0 and 4 ?C (D) 1.5 ?C and 2.5 ?C
Official Ans. by NTA (B)
Sol.
?
?
2
Kq(4 q)
F
d
? ? ?
2
dF K
[4 2q] 0
dq
d
q = 2
4
11. A. The drift velocity of electrons decreases with
the increase in the temperature of conductor.
B. The drift velocity is inversely proportional to
the area of cross-section of given conductor.
C. The drift velocity does not depend on the
applied potential difference to the conductor.
D. The drift velocity of electron is inversely
proportional to the length of the conductor.
E. The drift velocity increases with the increase in
the temperature of conductor.
Choose the correct answer from the options given
below:
(A) A and B only (B) A and D only
(C) B and E only (D) B and C only
Official Ans. by NTA (B)
Sol. Drift velocity =
? ??
??
??
e
E
m
d
eV
v
m
?? ? ? ? ?
?
? ? ? ?
? ? ? ?
?V = Potential difference applied across the wire
As temperature increases, relaxation time
decreases, hence V
d
decreases.
As per formula, ?
d
1
V
d
I
v
neA
? , as it is not mentioned that current is at
steady state neither it is mentioned that n is
constant for given conductor. So it can't be said
that v
d
is inversely proportional to A.
I = neAv
d
=
VV
A
R
?
?
d
V
v
ne
?
?
V
E
??
?
??
??
d
eE
v
m
?
?
? decrease with temperature increase.
First and fourth statements are correct.
12. A compass needle of oscillation magnetometer
oscillates 20 times per minute at a place P of dip
30°. The number of oscillations per minute become
10 at another place Q of 60° dip. The ratio of the
total magnetic field at the two places (B
Q
: B
P
) is:
(A) 3 : 4 (B) 4: 3
(C) 3 :2 (D) 2: 3
Official Ans. by NTA (A)
Sol. ??
H
I
T2
BM
1
P
I
T 3sec 2
(B cos30 )M
? ? ?
?
2
Q
I
T 6sec 2
(B cos60 )M
? ? ?
?
? ?
Q
P
31
B / 2
6
3
B
2
??
??
??
??
??
Q
P
B
3
6
3B
??
?
??
??
??
Q
P
B
3
4B
?
QP
B : B 3 : 4 ?
13. A cyclotron is used to accelerate protons. If the
operating magnetic field is 1.0 T and the radius of
the cyclotron 'dees' is 60 cm, the kinetic energy of
the accelerated protons in MeV will be :
[use m
p
= 1.6 × 10
–27
kg, e = 1.6 × 10
–19
C]
(A) 12 (B) 18
(C) 16 (D) 32
Official Ans. by NTA (B)
Sol. Kinetic energy of electron in cyclotron
=
??
??
??
??
2 2 2
0
q B r
2m
= 18 MeV
5
?
14. A series LCR circuit has L = 0.01 H, R = 10 ? and
C = 1 ?F and it is connected to ac voltage of
amplitude (V
m
) 50 V. At frequency 60% lower
than resonant frequency, the amplitude of current
will be approximately :
(A) 466 mA (B) 312 mA
(C) 238 mA (D) 196 mA
Official Ans. by NTA (C)
Sol. Resonant frequency,
4
0
1
10 rad/sec
LC
? ? ?
4
' .4 10 4000 rad/sec ? ? ? ?
??
?
0
0
22
CL
V
i 238 mA
R (X' – X' )
15. Identify the correct statements from the following
descriptions of various properties of
electromagnetic waves.
A. In a plane electromagnetic wave electric field
and magnetic field must be perpendicular to
each other and direction of propagation of
wave should be along electric field or magnetic
field.
B. The energy in electromagnetic wave is divided
equally between electric and magnetic fields.
C. Both electric field and magnetic field are
parallel to each other and perpendicular to the
direction of propagation of wave.
D. The electric field, magnetic field and direction
of propagation of wave must be perpendicular
to each other.
E. The ratio of amplitude of magnetic field to the
amplitude of electric field is equal to speed of
light.
Choose the most appropriate answer from the
options given below:
(A) D only
(B) B and D only
(C) B, C and E only
(D) A, B and E only
Official Ans. by NTA (B)
Sol. Second and fourth statements are correct.
16. Two coherent sources of light interfere. The
intensity ratio of two sources is 1 : 4. For this
interference pattern if the value of
?
?
max min
max min
II
II
is
equal to
??
??
21
3
, then
?
?
will be :
(A) 1.5 (B) 2 (C) 0.5 (D) 1
Official Ans. by NTA (B)
Sol. ?
1
2
I 1
I4
?
21
I 4I
? ? ? ?
max 1 1 1 1 1
I I 4I 2 I 4I 9I
? ? ?
min 1 1 1 1 1
I I 4I – 2 I 4I I
? ??
? ? ? ?
??
11
11
9I I 10 5 2 1
9I – I 8 4 1
? ? ? ? 21
?
? ? ?
?
2
2
1
17. With reference to the observations in photo-electric
effect, identify the correct statements from below:
A. The square of maximum velocity of
photoelectrons varies linearly with frequency
of incident light.
B. The value of saturation current increases on
moving the source of light away from the metal
surface.
C. The maximum kinetic energy of photo-electrons
decreases on decreasing the power of LED
(light emitting diode) source of light.
D. The immediate emission of photo-electrons out
of metal surface can not be explained by
particle nature of light/electromagnetic waves.
E. Existence of threshold wavelength can not be
explained by wave nature of
light/electromagnetic waves.
Choose the correct answer from the options given
below:
(A) A and B only (B) A and E only
(C) C and E only (D) D and E only
Official Ans. by NTA (B)
Sol. ??
2
max
1
mV hf –
2
Photoelectric effect can be explained by particle
nature of light. Threshold ? is max wavelength at
which emission takes place.
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