Electromagnetic Induction- 1 Practice Questions - DPP for NEET

 Page 1


DIRECTIONS (Q.1-Q.20) : There are 20 multiple choice
questions. Each question has 4 choices (a), (b), (c) and (d), out
of which ONLY ONE choice is correct.
Q.1 A loop of wire is placed in a magnetic field 
ˆ
B 0.02i =
r
T ..
Then the flux through the loop if its area vector
ˆ ˆˆ
A 30i 16j 23k = ++
r
 cm
2 
is
(a) 60 mWb (b) 32 m Wb
(c) 46 m Wb (d) 138 m Wb
Q.2 The magnetic flux passing perpendicular to the plane of
the coil and directed into the paper is varying according to
the relation f = 3t
2
 + 2t + 3, where f is in milliweber and
t is in second. Then the magnitude of emf induced in the
loop when t = 2 second is-
(a) 31 mV
(b) 19 mV
(c) 14 mV
(d) 6 mV
Q.3 A current carrying  solenoid is approaching a conducting
loop as shown in the figure. The direction of induced
current as observed by an observer on the other side of the
loop will be -
(a) anti-clockwise
(b) clockwise
V
(c) east
(d) west
Page 2


DIRECTIONS (Q.1-Q.20) : There are 20 multiple choice
questions. Each question has 4 choices (a), (b), (c) and (d), out
of which ONLY ONE choice is correct.
Q.1 A loop of wire is placed in a magnetic field 
ˆ
B 0.02i =
r
T ..
Then the flux through the loop if its area vector
ˆ ˆˆ
A 30i 16j 23k = ++
r
 cm
2 
is
(a) 60 mWb (b) 32 m Wb
(c) 46 m Wb (d) 138 m Wb
Q.2 The magnetic flux passing perpendicular to the plane of
the coil and directed into the paper is varying according to
the relation f = 3t
2
 + 2t + 3, where f is in milliweber and
t is in second. Then the magnitude of emf induced in the
loop when t = 2 second is-
(a) 31 mV
(b) 19 mV
(c) 14 mV
(d) 6 mV
Q.3 A current carrying  solenoid is approaching a conducting
loop as shown in the figure. The direction of induced
current as observed by an observer on the other side of the
loop will be -
(a) anti-clockwise
(b) clockwise
V
(c) east
(d) west
2
DPP/ P 44
Q.4 Consider the arrangement shown in figure in which the north
pole of a magnet is moved  away from a thick conducting
loop containing capacitor. Then excess positive charge will
arrive on
(a) plate a
(b) plate b
(c) both plates a and b
(d) ne ithe r a nor b pla te s
Q.5 An electron moves along the line AB, which lies in the
same plane as a circular loop of conducting wires as shown
in the diagram. What will be the direction of current
induced if any, in the loop?
(a) No current will be induced
(b) The current will be clockwise       
A B
(c) The current will be anticlockwise
(d)  The current will change direction as the electron passes by
Q.6 When a small piece of wire passes between the magnetic
poles of a horse-shoe magnet in 0.1 sec, emf of 4 × 10
–3
volt is induced in it. The magnetic flux between the poles
is :
(a) 4 × 10
–2
 weber (b) 4 × 10
–3
 weber
(c) 4 × 10
–4
 weber (d) 4 × 10
–6
 weber
Q.7 The normal magnetic flux passing through a coil changes
with time according to following equation
f = 10t
2
 + 5t + 1
where f is in milliweber and t is in second. The value of
induced e.m.f. produced in the coil at t = 5s will be –
(a) zero (b) 1 V (c) 2 V (d) 0.105 V
Q.8 A bicycle wheel of radius 0.5 m has 32 spokes. It is rotating
at the rate of 120 revolutions per minute, perpendicular to
the horizontal component of earth's magnetic field
B
H
 = 4 × 10
–5
 tesla. The emf induced between the rim and
the centre of the wheel will be-
(a) 6.28 × 10
–5
 V (b) 4.8 × 10
–5
 V
(c) 6.0 × 10
–5
 V (d) 1.6 × 10
–5
 V
Q.9 A thin semicircular conducting ring of radius R is falling
with its plane vertical in a horizontal magnetic induction
B. At the position MNQ shown in the fig, the speed of the
ring is V. The potential difference developed across the
semicircular ring is
(a) Zero
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
B
N
V
M Q
(b) B vR
2
/2 and M is at higher potential
(c) pRBV and Q is at higher potential
(d) 2RBV and Q is at higher potential
Q.10 An aeroplane having a distance of 50 metre between the
edges of its wings is flying horizontally with a speed of
360km/hour. If the vertical component of earth’s magnetic
field is 4 × 10
–4
 weber/m
2
, then the induced emf between
the edges of its wings will be –
(a) 2 mV (b) 2 V (c) 0.2 V (d) 20 V
Q.11 At certain location in the northern hemisphere, the earth's
magnetic field has a magnitude of 42 mT and points down
ward at 57º to vertical. The flux through a horizontal surface
of area 2.5 m
2
 will be-  (Given cos 33º = 0.839, cos 57º =
0.545)
(a) 42 × 10
–6
 Wb/m
2
(b) 42 × 10
–6
 Wb/m
2
(c) 57 × 10
–6
 Wb/m
2
(d) 57 × 10
–6
 Wb/m
2
Q.12 A square loop of side a is rotating about its diagonal with
angular velocity w in a perpendicular magnetic field as shown
in the figure. If the number of turns in it is
10 then the magnetic flux linked with the
loop at any instant will be–
(a) 10Ba
2
 cos wt (b)  10Ba                    
×× × × ××
× × ×××
× × ×× ×
× ×× ××
×× × ××
×× × ××
×
×
×
×
×
× ××× ×
×× × ××
×
×
w
(c) 10Ba
2
(d)  20Ba
2
Q.13 Two identical coaxial circular loops carry current i each
circulating in the clockwise direction. If the loops are
approaching each other, then
(a) Current in each loop increases
(b) Current in each loop remains the same
(c) Current in each loop decreases
(d) Current in one-loop increases and in the other it
decreases
Q.14 The distance between the ends of wings of an aeroplane is
3m. This aeroplane is descending down with a speed of
300 km/hour. If the horizontal component of earths
magnetic field is 0.4 gauss then the value of e.m.f. induced
in the wings of the plane will be –
(a) 1 V (b) 2 V (c) 0.01 V (d) 0.1 V
Page 3


DIRECTIONS (Q.1-Q.20) : There are 20 multiple choice
questions. Each question has 4 choices (a), (b), (c) and (d), out
of which ONLY ONE choice is correct.
Q.1 A loop of wire is placed in a magnetic field 
ˆ
B 0.02i =
r
T ..
Then the flux through the loop if its area vector
ˆ ˆˆ
A 30i 16j 23k = ++
r
 cm
2 
is
(a) 60 mWb (b) 32 m Wb
(c) 46 m Wb (d) 138 m Wb
Q.2 The magnetic flux passing perpendicular to the plane of
the coil and directed into the paper is varying according to
the relation f = 3t
2
 + 2t + 3, where f is in milliweber and
t is in second. Then the magnitude of emf induced in the
loop when t = 2 second is-
(a) 31 mV
(b) 19 mV
(c) 14 mV
(d) 6 mV
Q.3 A current carrying  solenoid is approaching a conducting
loop as shown in the figure. The direction of induced
current as observed by an observer on the other side of the
loop will be -
(a) anti-clockwise
(b) clockwise
V
(c) east
(d) west
2
DPP/ P 44
Q.4 Consider the arrangement shown in figure in which the north
pole of a magnet is moved  away from a thick conducting
loop containing capacitor. Then excess positive charge will
arrive on
(a) plate a
(b) plate b
(c) both plates a and b
(d) ne ithe r a nor b pla te s
Q.5 An electron moves along the line AB, which lies in the
same plane as a circular loop of conducting wires as shown
in the diagram. What will be the direction of current
induced if any, in the loop?
(a) No current will be induced
(b) The current will be clockwise       
A B
(c) The current will be anticlockwise
(d)  The current will change direction as the electron passes by
Q.6 When a small piece of wire passes between the magnetic
poles of a horse-shoe magnet in 0.1 sec, emf of 4 × 10
–3
volt is induced in it. The magnetic flux between the poles
is :
(a) 4 × 10
–2
 weber (b) 4 × 10
–3
 weber
(c) 4 × 10
–4
 weber (d) 4 × 10
–6
 weber
Q.7 The normal magnetic flux passing through a coil changes
with time according to following equation
f = 10t
2
 + 5t + 1
where f is in milliweber and t is in second. The value of
induced e.m.f. produced in the coil at t = 5s will be –
(a) zero (b) 1 V (c) 2 V (d) 0.105 V
Q.8 A bicycle wheel of radius 0.5 m has 32 spokes. It is rotating
at the rate of 120 revolutions per minute, perpendicular to
the horizontal component of earth's magnetic field
B
H
 = 4 × 10
–5
 tesla. The emf induced between the rim and
the centre of the wheel will be-
(a) 6.28 × 10
–5
 V (b) 4.8 × 10
–5
 V
(c) 6.0 × 10
–5
 V (d) 1.6 × 10
–5
 V
Q.9 A thin semicircular conducting ring of radius R is falling
with its plane vertical in a horizontal magnetic induction
B. At the position MNQ shown in the fig, the speed of the
ring is V. The potential difference developed across the
semicircular ring is
(a) Zero
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
B
N
V
M Q
(b) B vR
2
/2 and M is at higher potential
(c) pRBV and Q is at higher potential
(d) 2RBV and Q is at higher potential
Q.10 An aeroplane having a distance of 50 metre between the
edges of its wings is flying horizontally with a speed of
360km/hour. If the vertical component of earth’s magnetic
field is 4 × 10
–4
 weber/m
2
, then the induced emf between
the edges of its wings will be –
(a) 2 mV (b) 2 V (c) 0.2 V (d) 20 V
Q.11 At certain location in the northern hemisphere, the earth's
magnetic field has a magnitude of 42 mT and points down
ward at 57º to vertical. The flux through a horizontal surface
of area 2.5 m
2
 will be-  (Given cos 33º = 0.839, cos 57º =
0.545)
(a) 42 × 10
–6
 Wb/m
2
(b) 42 × 10
–6
 Wb/m
2
(c) 57 × 10
–6
 Wb/m
2
(d) 57 × 10
–6
 Wb/m
2
Q.12 A square loop of side a is rotating about its diagonal with
angular velocity w in a perpendicular magnetic field as shown
in the figure. If the number of turns in it is
10 then the magnetic flux linked with the
loop at any instant will be–
(a) 10Ba
2
 cos wt (b)  10Ba                    
×× × × ××
× × ×××
× × ×× ×
× ×× ××
×× × ××
×× × ××
×
×
×
×
×
× ××× ×
×× × ××
×
×
w
(c) 10Ba
2
(d)  20Ba
2
Q.13 Two identical coaxial circular loops carry current i each
circulating in the clockwise direction. If the loops are
approaching each other, then
(a) Current in each loop increases
(b) Current in each loop remains the same
(c) Current in each loop decreases
(d) Current in one-loop increases and in the other it
decreases
Q.14 The distance between the ends of wings of an aeroplane is
3m. This aeroplane is descending down with a speed of
300 km/hour. If the horizontal component of earths
magnetic field is 0.4 gauss then the value of e.m.f. induced
in the wings of the plane will be –
(a) 1 V (b) 2 V (c) 0.01 V (d) 0.1 V
DPP/ P 44
3
Q.15A gramophone disc of brass of diameter 30 cm rotates
horizontally at the rate of 100/3 revolutions per minute. If
the vertical component of the earth's magnetic field be 0.01
weber/metre
2
, then  the emf induced between the centre
and the rim of the disc will be-
(a) 7.065 × 10
–4
 V (b) 3.9 × 10
–4
 V
(c) 2.32 × 10
–4
 V (d) None of the above
Q.16 A closed coil consists of 500 turns on a rectangular frame
of area 4.0 cm
2
 and has a resistance of 50 ohm. The coil is
kept with its plane perpendicular to a uniform magnetic
field of 0.2 weber/meter
2
. The amount of charge flowing
through the coil if it is turned over (rotated through 180º)
will be -
(a) 1.6 × 10
–19 
C (b) 1.6 × 10
–9 
C
(c) 1.6 × 10
–3
 C (d) 1.6 × 10
–2
 C
Q.17 A copper disc of radius 0.1 m rotates about its centre with
10 revolution per second in 'a uniform magnetic field of
0.1 T. The emf induced across the radius of the disc is -
(a) p/10 V (b)2p/10 V (c) 10p mV (d) 20p mV
Q.18 Two rail tracks, insulated from each other and the ground,
are connected to milli voltmeter. What is the reading of
the milli voltmeter when a train passes at a speed of 180
km/hr along the track ? Given that – the horizontal
component of earth’s magnetic field B
H 
is 0.2 × 10
–4
 Wb/
m
2
 and rails are separated by 1 metre.
(a) 1 mV (b) 10 mV (c) 100 mV (d) 1 V
Q.19 The annular disc of copper, with inner radius a and outer
radius b is rotating with a uniform angular speed w, in a
region where a uniform magnetic field B along the axis of
rotation exists. Then, the emf induced between inner side
and the outer rim of the disc is-
(a) Zero (b)
1
2
Bwa
2
(c)
1
2
Bwb
2
(d)
1
2
Bw (b
2 
– a
2
)
Q.20 A conducting wire in the shape of Y with each side of length
l is moving in a uniform magnetic field B, with a uniform
speed v as shown in fig. The induced emf at the two ends X
and Y of the wire will be-
(a) zero
(b) 2 B lv
(c) 2 B lv sin (q/2)
(d) 2 B lv cos (q/2)
DIRECTIONS (Q.21-Q.23) : In the following questions,
more than one of the answers  given are correct. Select the
correct answers and mark it according to the following
codes:
Codes :
(a) 1, 2 and 3 are correct (b) 1 and 2 are correct
(c) 2 and 4 are correct (d) 1 and 3 are correct
Q.21 A rectangular coil of size 10 cm ×20 cm has 60 turns. It is
rotating about one of its diagonals in magnetic field
0.5 Wb/m
2
 with a rate of 1800 revolution per minute. The
induced e.m.f. in the coil can be
(1) 111 V (2) 112 V (3) 113 V (4) 114 V
Q.22A closed coil of copper whose area is 1m × 1m is free to
rotate about an axis. The coil is placed perpendicular to a
magnetic field of 0.10 Wb/m
2
. It is rotated through 180º
in 0.01 second. Then  (The resistance of the coil is 2.0W)
(1) The induced e.m.f. in the coil is 20 V
(2) The induced current in the coil is 10 A
(3) The induced e.m.f. in the coil is 10 V
(4) The induced current in the coil is 20 A
Q.23 5.5 × 10
–4
 magnetic flux lines are passing through a coil
of resistance 10 ohm and number of turns 1000. If the
number of flux lines reduces to 5 × 10
–5
 in 0.1 sec. Then
(1) The electromotive force induced in the coil is 5V
(2) The electromotive force induced in the coil is
5 × 10
–4
 V
(3) The current induced in the coil is 0.5 A
(4) The current induced in the coil is 10 A
DIRECTIONS (Q.24-Q.26) : Read the passage given below
and answer the questions that follows :
In the figure shown, the rod has a resistance R, the horizontal
rails have negligible friction. Magnetic field of intensity B is
directed perpendicular into the plane of paper. A cell of e.m.f. E
and negligible internal resistance is connected between points a
and b. The rod is initially at rest.
Page 4


DIRECTIONS (Q.1-Q.20) : There are 20 multiple choice
questions. Each question has 4 choices (a), (b), (c) and (d), out
of which ONLY ONE choice is correct.
Q.1 A loop of wire is placed in a magnetic field 
ˆ
B 0.02i =
r
T ..
Then the flux through the loop if its area vector
ˆ ˆˆ
A 30i 16j 23k = ++
r
 cm
2 
is
(a) 60 mWb (b) 32 m Wb
(c) 46 m Wb (d) 138 m Wb
Q.2 The magnetic flux passing perpendicular to the plane of
the coil and directed into the paper is varying according to
the relation f = 3t
2
 + 2t + 3, where f is in milliweber and
t is in second. Then the magnitude of emf induced in the
loop when t = 2 second is-
(a) 31 mV
(b) 19 mV
(c) 14 mV
(d) 6 mV
Q.3 A current carrying  solenoid is approaching a conducting
loop as shown in the figure. The direction of induced
current as observed by an observer on the other side of the
loop will be -
(a) anti-clockwise
(b) clockwise
V
(c) east
(d) west
2
DPP/ P 44
Q.4 Consider the arrangement shown in figure in which the north
pole of a magnet is moved  away from a thick conducting
loop containing capacitor. Then excess positive charge will
arrive on
(a) plate a
(b) plate b
(c) both plates a and b
(d) ne ithe r a nor b pla te s
Q.5 An electron moves along the line AB, which lies in the
same plane as a circular loop of conducting wires as shown
in the diagram. What will be the direction of current
induced if any, in the loop?
(a) No current will be induced
(b) The current will be clockwise       
A B
(c) The current will be anticlockwise
(d)  The current will change direction as the electron passes by
Q.6 When a small piece of wire passes between the magnetic
poles of a horse-shoe magnet in 0.1 sec, emf of 4 × 10
–3
volt is induced in it. The magnetic flux between the poles
is :
(a) 4 × 10
–2
 weber (b) 4 × 10
–3
 weber
(c) 4 × 10
–4
 weber (d) 4 × 10
–6
 weber
Q.7 The normal magnetic flux passing through a coil changes
with time according to following equation
f = 10t
2
 + 5t + 1
where f is in milliweber and t is in second. The value of
induced e.m.f. produced in the coil at t = 5s will be –
(a) zero (b) 1 V (c) 2 V (d) 0.105 V
Q.8 A bicycle wheel of radius 0.5 m has 32 spokes. It is rotating
at the rate of 120 revolutions per minute, perpendicular to
the horizontal component of earth's magnetic field
B
H
 = 4 × 10
–5
 tesla. The emf induced between the rim and
the centre of the wheel will be-
(a) 6.28 × 10
–5
 V (b) 4.8 × 10
–5
 V
(c) 6.0 × 10
–5
 V (d) 1.6 × 10
–5
 V
Q.9 A thin semicircular conducting ring of radius R is falling
with its plane vertical in a horizontal magnetic induction
B. At the position MNQ shown in the fig, the speed of the
ring is V. The potential difference developed across the
semicircular ring is
(a) Zero
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
B
N
V
M Q
(b) B vR
2
/2 and M is at higher potential
(c) pRBV and Q is at higher potential
(d) 2RBV and Q is at higher potential
Q.10 An aeroplane having a distance of 50 metre between the
edges of its wings is flying horizontally with a speed of
360km/hour. If the vertical component of earth’s magnetic
field is 4 × 10
–4
 weber/m
2
, then the induced emf between
the edges of its wings will be –
(a) 2 mV (b) 2 V (c) 0.2 V (d) 20 V
Q.11 At certain location in the northern hemisphere, the earth's
magnetic field has a magnitude of 42 mT and points down
ward at 57º to vertical. The flux through a horizontal surface
of area 2.5 m
2
 will be-  (Given cos 33º = 0.839, cos 57º =
0.545)
(a) 42 × 10
–6
 Wb/m
2
(b) 42 × 10
–6
 Wb/m
2
(c) 57 × 10
–6
 Wb/m
2
(d) 57 × 10
–6
 Wb/m
2
Q.12 A square loop of side a is rotating about its diagonal with
angular velocity w in a perpendicular magnetic field as shown
in the figure. If the number of turns in it is
10 then the magnetic flux linked with the
loop at any instant will be–
(a) 10Ba
2
 cos wt (b)  10Ba                    
×× × × ××
× × ×××
× × ×× ×
× ×× ××
×× × ××
×× × ××
×
×
×
×
×
× ××× ×
×× × ××
×
×
w
(c) 10Ba
2
(d)  20Ba
2
Q.13 Two identical coaxial circular loops carry current i each
circulating in the clockwise direction. If the loops are
approaching each other, then
(a) Current in each loop increases
(b) Current in each loop remains the same
(c) Current in each loop decreases
(d) Current in one-loop increases and in the other it
decreases
Q.14 The distance between the ends of wings of an aeroplane is
3m. This aeroplane is descending down with a speed of
300 km/hour. If the horizontal component of earths
magnetic field is 0.4 gauss then the value of e.m.f. induced
in the wings of the plane will be –
(a) 1 V (b) 2 V (c) 0.01 V (d) 0.1 V
DPP/ P 44
3
Q.15A gramophone disc of brass of diameter 30 cm rotates
horizontally at the rate of 100/3 revolutions per minute. If
the vertical component of the earth's magnetic field be 0.01
weber/metre
2
, then  the emf induced between the centre
and the rim of the disc will be-
(a) 7.065 × 10
–4
 V (b) 3.9 × 10
–4
 V
(c) 2.32 × 10
–4
 V (d) None of the above
Q.16 A closed coil consists of 500 turns on a rectangular frame
of area 4.0 cm
2
 and has a resistance of 50 ohm. The coil is
kept with its plane perpendicular to a uniform magnetic
field of 0.2 weber/meter
2
. The amount of charge flowing
through the coil if it is turned over (rotated through 180º)
will be -
(a) 1.6 × 10
–19 
C (b) 1.6 × 10
–9 
C
(c) 1.6 × 10
–3
 C (d) 1.6 × 10
–2
 C
Q.17 A copper disc of radius 0.1 m rotates about its centre with
10 revolution per second in 'a uniform magnetic field of
0.1 T. The emf induced across the radius of the disc is -
(a) p/10 V (b)2p/10 V (c) 10p mV (d) 20p mV
Q.18 Two rail tracks, insulated from each other and the ground,
are connected to milli voltmeter. What is the reading of
the milli voltmeter when a train passes at a speed of 180
km/hr along the track ? Given that – the horizontal
component of earth’s magnetic field B
H 
is 0.2 × 10
–4
 Wb/
m
2
 and rails are separated by 1 metre.
(a) 1 mV (b) 10 mV (c) 100 mV (d) 1 V
Q.19 The annular disc of copper, with inner radius a and outer
radius b is rotating with a uniform angular speed w, in a
region where a uniform magnetic field B along the axis of
rotation exists. Then, the emf induced between inner side
and the outer rim of the disc is-
(a) Zero (b)
1
2
Bwa
2
(c)
1
2
Bwb
2
(d)
1
2
Bw (b
2 
– a
2
)
Q.20 A conducting wire in the shape of Y with each side of length
l is moving in a uniform magnetic field B, with a uniform
speed v as shown in fig. The induced emf at the two ends X
and Y of the wire will be-
(a) zero
(b) 2 B lv
(c) 2 B lv sin (q/2)
(d) 2 B lv cos (q/2)
DIRECTIONS (Q.21-Q.23) : In the following questions,
more than one of the answers  given are correct. Select the
correct answers and mark it according to the following
codes:
Codes :
(a) 1, 2 and 3 are correct (b) 1 and 2 are correct
(c) 2 and 4 are correct (d) 1 and 3 are correct
Q.21 A rectangular coil of size 10 cm ×20 cm has 60 turns. It is
rotating about one of its diagonals in magnetic field
0.5 Wb/m
2
 with a rate of 1800 revolution per minute. The
induced e.m.f. in the coil can be
(1) 111 V (2) 112 V (3) 113 V (4) 114 V
Q.22A closed coil of copper whose area is 1m × 1m is free to
rotate about an axis. The coil is placed perpendicular to a
magnetic field of 0.10 Wb/m
2
. It is rotated through 180º
in 0.01 second. Then  (The resistance of the coil is 2.0W)
(1) The induced e.m.f. in the coil is 20 V
(2) The induced current in the coil is 10 A
(3) The induced e.m.f. in the coil is 10 V
(4) The induced current in the coil is 20 A
Q.23 5.5 × 10
–4
 magnetic flux lines are passing through a coil
of resistance 10 ohm and number of turns 1000. If the
number of flux lines reduces to 5 × 10
–5
 in 0.1 sec. Then
(1) The electromotive force induced in the coil is 5V
(2) The electromotive force induced in the coil is
5 × 10
–4
 V
(3) The current induced in the coil is 0.5 A
(4) The current induced in the coil is 10 A
DIRECTIONS (Q.24-Q.26) : Read the passage given below
and answer the questions that follows :
In the figure shown, the rod has a resistance R, the horizontal
rails have negligible friction. Magnetic field of intensity B is
directed perpendicular into the plane of paper. A cell of e.m.f. E
and negligible internal resistance is connected between points a
and b. The rod is initially at rest.
4
DPP/ P 44
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
×
E
a
b
ROD
B
L
Q.24The velocity of the rod as a function of time t (where
t = mR/B l
2
) is
(a)  
t/
E
(1e)
B
-t
-
l
(b)
t/
E
(1e)
B
-t
+
l
(c)  
t/
3E
(1e)
2B
-t
-
l
(d)
t/
E
(1e)
2B
-t
-
l
Q.25 After some time the rod will approach a terminal speed.
The speed is
(a)
3E
2B l
(b)
E
2B l
(c)
E
B l
(d)
2E
Bl
Q.26 The current when the rod attains its terminal speed is
(a)
2E
R
(b)
E
R
(c)
3E
2R
(d) zero
DIRECTIONS (Q. 27-Q.29) : Each of these questions
contains two statements: Statement-1 (Assertion) and
Statement-2 (Reason). Each of these questions has four
alternative choices, only one of which is the correct answer.
You have to select the correct choice.
(a) Statement-1 is True, Statement-2 is True; Statement-2 is a
correct explanation for  Statement-1.
(b) Statement-1 is True, Statement-2 is True; Statement-2 is
NOT a correct explanation for Statement-1.
(c) Statement -1 is False, Statement-2 is True.
(d) Statement -1 is True, Statement-2 is False.
Q.27 Statement-1 : The induced e.m.f. and current will be same
in two identical loops of copper and aluminium, when
rotated with same speed in the same magnetic field.
Statement-2  : Induced e.m.f. is proportional to rate of
change of magnetic field while induced current depends
on resistance of wire.
Q.28Statement-1 : An aircraft flies along the meridian, the
potential at the ends of its wings will be the same.
Statement-2 : Whenever there is change in the magnetic
flux e.m.f. induces.
Q.29Statement-1 : Lenz’s law violates the principle of
conservation of energy.
Statement-2 : Induced e.m.f. opposes the change in
magnetic flux responsible for its production.