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AL-MC-E&M / p.1
1.
(88-I-36)
P and Q represent two long, straight, parallel, conducting wires separated by a distance of 0.5 a, as shown in the
figure above. Each of them carries a current I flowing into the plane of the paper. The magnitude of y-component
of the magnetic induction at point R is
2.
A.
zero.
B.
0 I
 (1.17).
2 a
C.
0 I
 (4.00).
2 a
D.
0 I
 (4.17).
2 a
E.
0 I
 (5.38).
2 a
(88-I-37)
A particle of mass m and charge q moves in a circular orbit in a magnetic field B. The time taken to complete a
single orbit is
3.
A.
Bq / (2  m).
B.
2  m / (Bq).
C.
2 mq / (B  ).
D.
Bm / (2  q).
E.
2  / (mBq).
(88-I-38)
In the figure shown, MN is a fixed long conductor, carrying a current
to MN. When a current
I1 . HK is another conductor perpendicular
I 2 is allowed to pass through HK in the direction shown, the force on HK
AL-MC-E&M / p.2
4.
A.
acts in the +y direction.
B.
acts in the –y direction.
C.
acts in the +x direction.
D.
acts in the –x direction.
E.
is zero.
(88-I-39)
Two coaxial solenoids P and Q are arranged as shown. The cross-sectional areas of P and Q are
respectively. P contains
A1 and A2
N1 turns while Q contains N 2 turns. Q is now connected to a power supply so that
the current through it rises at a uniform rate S. The maximum e.m.f. induced in P is
5.
A.
 0 N1 N 2 A1 S .
B.
 0 N1 N 2 A2 S.
C.
 0 N1 N 2 A1 S / L
D.
 0 N1 N 2 A2 S / L
E.
zero.
(88-I-42)
A rectangular wire frame surrounds a uniform magnetic field which is confined to a square region as shown in the
diagram. The magnetic field is situated at the centre of the frame and is perpendicular to the plane of the paper. If
the frame moves to the right with a uniform velocity, which of the graphs below best represents the variation of
the induced current i with time t?
(The clockwise direction of the current is taken as positive.)
AL-MC-E&M / p.3
6.
(89-I-32)
A circular loop carrying a current I is placed in a uniform magnetic field B in the xy plane as shown. If the loop is
free to move, the magnetic forces will cause it to
7.
A.
rotate about the y-axis as indicated by p.
B.
rotate about the y-axis as indicated by q.
C.
rotate about the x-axis as indicated by r.
D.
rotate about the x-axis as indicated by s.
E.
remain stationary.
(89-I-33)
Which of the following statements about a d.c. motor is FALSE?
A.
The back e.m.f. developed dissipates the input energy in Joule heating.
B.
If the motor is stopped by some obstruction, the current through the coil will increase.
C.
The direction of rotation can be predicted by Fleming’s left hand rule.
D.
A single-coil motor will not start when it is switched on, if the plane of the coil is perpendicular to the
magnetic field.
E.
An ideal d.c. motor develops a back e.m.f. equal to the applied e.m.f.
AL-MC-E&M / p.4
8.
(89-I-35)
A length of wire is bent to form a circular coil of one turn. The coil is placed in a uniform magnetic field with its
plane normal to the direction of the field. The flux linkage through the coil is
 . The same length of wire is now
bent to form a double loop of smaller radius. The flux linkage is now
A.
B.
C.
D.
E.
9.
 /4.
 /2.
.
2 .
4 .
(89-I-36)
Two rectangular wire loops A and B are placed in the same plane. Loop A includes a battery E and switch K,
which is initially open. If K is suddenly closed, what is the direction of the induced current in loop B? Is the force
between the two loops attractive or repulsive?
Direction of current
Nature of force
A.
clockwise
attractive
B.
clockwise
repulsive
C.
anticlockwise
attractive
D.
anticlockwise
repulsive
E.
no current
no net force
10. (90-I-36)
A d.c. motor is connected to a 12 V battery. Which of the following statements is connect?
(1)
As the motor gathers speed, the current through the motor increases.
(2)
As the motor gathers speed, the torque acting on the rotating coil increases.
(3)
If the efficiency is 75% at steady state, the back e.m.f. is then 9 V.
A.
(1), (2) and (3)
B.
(1) and (2) only
C.
(2) and (3) only
D.
(1) only
E.
(3) only
AL-MC-E&M / p.5
11. (90-I-38)
The self-inductance of an air-core solenoid can be increased by
(1)
increasing the current through it.
(2)
increasing the frequency of the supply.
(3)
placing a ferro-magnetic material inside the solenoid.
A. (1), (2) and (3)
B. (1) and (2) only
C. (2) and (3) only
D. (1) only
E. (3) only
12. (91-I-34)
The magnetic field due to a steady current in the long air-core solenoid (uniformly wound) shown below is
8  10 3 T at X and 1  10 3 T at Y.
If an identical solenoid is connected to the end of the first so as to extend it to as far as Y, and the same current as
before is passed through the complete solenoid, the magnetic field at Y will then be
A.
B.
C.
D.
E.
13. (91-I-35)
7  10 3 T
8  10 3 T
9  10 3 T
16  10 3 T
17  10 3 T
AL-MC-E&M / p.6
In the above figure, a copper disc rotates uniformly between the pole-pieces of a powerful magnet (not shown in
figure) in a clockwise direction. P and Q are metallic brushes making contact with the axle and the edge of the
disc respectively. Which of the following statements is correct?
A.
No current flows through R, because there is no flux change through the disc.
B.
No current flows through R because P and Q are at the same horizontal level.
C.
An alternating current flows through R.
D.
A steady current flows from P to Q through R.
E.
A steady current flows from Q to P through R.
14. (91-I-36)
An additional mechanical load is applied to a rotating motor. Which of the following is/are true?
(1)
The motor will decrease in speed.
(2)
The e.m.f. induced in the rotating coil will decrease.
(3)
More power will be drawn from the power supply.
A.
(1), (2) and (3)
B.
(1) and (2) only
C.
(2) and (3) only
D.
(1) only
E.
(3) only
15. (91-I-37)
It is desired to re-design a moving coil galvanometer so as to make it four times as sensitive. Which of the
following would alone achieve the desired result?
(1)
Increasing the magnetic flux density of the permanent magnet to twice its value and doubling the
cross-sectional area of the coil.
(2)
Providing the coil with a shunt so that only a quarter of the input current flows through the coil itself.
(3)
Changing the suspension characteristics so that four times as great a couple is needed to cause one radian
twist.
A.
(1), (2) and (3)
B.
(1) and (2) only
AL-MC-E&M / p.7
C.
(2) and (3) only
D.
(1) only
E.
(3) only
16. (92-I-33)
A moving-coil galvanometer with a coil of area A and N turns has a full-scale deflection for a current i. If the coil
were of area 3 A and 2 N turns, the current which would give full scale deflection would be
17.
A.
i/6
B.
2i/3
C.
i
D.
3i/2
E.
6i
(92-I-34)
A square coil of N turns and area A carries a current I. The coil is free to rotate about the axis XY which is normal
to a uniform magnetic field B. When the field makes an angle

with the plane of the coil, what are the
magnitude and direction of the torque acting on the coil as detected by an observer at X?
Magnitude
Direction
A.
BANI cos
clockwise
B.
BANI sin 
clockwise
C.
BANI cos
anticlockwise
D.
BANI sin 
anticlockwise
E.
none of the above
AL-MC-E&M / p.8
18.
(92-I-35)
When switch S is closed, the steel strip will
A.
remain stationary
B.
remain attracted to the iron core
C.
vibrate at a frequency of 50 Hz
D.
vibrate at a frequency of 100 Hz
E.
vibrate at a frequency of 200 Hz
19. (92-I-36)
Two parallel straight conductors separated by a distance r carry currents in the same direction. Which of the
following statements is/are correct?
(1)
The two wires attract each other.
(2)
The force acting on each wire is inversely proportional to r2.
(3)
The wires produce a magnetic field with maximum flux density midway between them.
A.
(1), (2) and (3)
B.
(1) and (2) only
C.
(2) and (3) only
D.
(1) only
E.
(3) only
20. (92-I-38)
In the above figure, when the metal rod PQ moves with constant velocity across a uniform magnetic field, a p.d.
is induced across the rod. Which of the following statements is/are correct?
(1)
The magnitude of the p.d. depends on the length of the rod.
AL-MC-E&M / p.9
(2)
Q is at a higher potential than P.
(3)
A force is acting on the rod to oppose its motion.
A.
(1), (2) and (3)
B.
(1) and (2) only
C.
(2) and (3) only
D.
(1) only
E.
(3) only
21. (92-I-40)
A metal ring is made to float above a coil carrying alternating current. Which of the following will affect the
height of the ring?
(1)
the resistivity of the ring
(2)
the density of the ring
(3)
the frequency of the alternating current
A.
(1), (2) and (3)
B.
(1) and (2) only
C.
(2) and (3) only
D.
(1) only
E.
(3) only
22. (93-I-36)
The above figure shows two long parallel straight wires separated by a distance of 0.2 m, carrying currents of 1 A
in opposite directions. The magnetic field at a point X mid-way between the wires is
(Given : permeability constant
0
= 4  10 TmA
7
1
)
AL-MC-E&M / p.10
A.
B.
C.
D.
E.
23.
0T
2  10 6 T
2  10 6 T
4  10 6 T
4  10 6 T
into paper
out of paper
into paper
out of paper
(93-I-37)
A 10 V battery of negligible internal resistance is applied to a d.c. motor M with armature resistance 5  . If the
ammeter A of negligible internal resistance shows a reading of 0.4 A, the maximum useful output power delivered
by the motor is
A.
0.8 W
B.
1.6 W
C.
2.4 W
D.
3.2 W
E.
4.0 W
AL-MC-E&M / p.11
24.
(93-I-39)
Two coils are linked by a soft iron bar as shown. A current source is connected to the primary coil. The primary
current I p varies with time as shown by the graph below :
Which of the following sketches represents the variation of the voltage across the secondary coil
25.
VAB with time?
(94-IIA-31)
For two long, straight parallel conducting wires carrying the same current, the magnitude of the force acting on a
section of the wires depends on
(1)
the distance between the wires
(2)
the length of that section of the wires
AL-MC-E&M / p.12
(3)
26.
the directions of current flow in the wires
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(94-IIA-32)
The current in a coil changes steadily from 3A to 6A in 75 ms so that a back e.m.f of 4 V is induced in the coil.
The self-inductance of the coil is
27.
A.
0.025 H
B.
0.10 H
C.
40 H
D.
100 H
E.
160 H
(94-IIA-33)
When the switch S in the above circuit is closed, the variation of quantity y with time t is plotted as shown. The
quantity y could be
28.
(1)
the current i in the circuit.
(2)
The voltage
V1 across the resistor.
(3)
The voltage
V2 across the inductor.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(95-IIA-28)
AL-MC-E&M / p.13
The mechanical power output of a d.c. motor is always less than the electrical power input. Which of the
following can be an explanation of this?
29.
(1)
heat loss in the coil of the motor
(2)
work done against friction
(3)
work done against the back e.m.f. generated by the rotating coil
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(95-IIA-30)
The machines in a factory consume 10 kW of electrical power at a voltage of 500 V. If the generator is connected
to the factory through cables of total resistance 0.2  , the e.m.f. produced by the generator should be
30.
A.
500 V
B.
501 V
C.
502 V
D.
504 V
E.
508 V
(95-IIA-32)
25
In a Hall probe, the slice of semiconductor inside has 10 charge-carriers per cubic metre. When a steady current
of 0.4 A passes through the slice and a uniform magnetic field of 0.1 T applies perpendicularly to it, a Hall voltage
of 20  V is set up. Find the thickness of the slice.
(Given : electronic charge = 1.6  10
A.
B.
C.
D.
E.
31.
(95-IIA-34)
0.9  10 3 m
1.1  10 3 m
1.3  10 3 m
1.5  10 3 m
1.7  10 3 m
19
C)
AL-MC-E&M / p.14
Particles A and B moving at the same speed enter a square region of uniform magnetic field as shown. Particle A
leaves at X while particle B leaves at Y. If the charge to mass ratio of particle A is k, what is that of particle B?
A.
k/2
B.
k/4
C.
k
D.
2k
E.
4k
32. (95-IIA-35)
A magnet is moved along a perpendicular direction towards a sheet of copper. Which of the following statements
is/are correct?
33.
(1)
Eddy current flows in the sheet.
(2)
Temperature of the sheet increases.
(3)
Repulsive force is experienced by the magnet.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(95-IIA-39)
A solenoid of
n1 turns per metre and cross-sectional area A1 carries a current I. It is inserted into the core of
another larger solenoid of
N 2 turns and cross-sectional area A2 . If the current in the smaller solenoid drops
AL-MC-E&M / p.15
uniformly to zero in time t, what is the e.m.f. induced in the larger solenoid?
A.
2 o n1 IA1 N 2 / t
B.
2 o n1 IA2 N 2 / t
C.
 o n1 IA1 A2 / t
D.
 o n1 IA2 N 2 / t
E.
 o n1 IA1 N 2 / t
34. (96-IIA-26)
Four infinitely long straight parallel wires P, Q, R, S carrying equal currents are situated at the corners of a square
as shown. The currents in P, Q are into paper and those in R, S are out of paper. What is the direction of the
resultant magnetic induction at the centre of the square?
35.
A.
I
B.
II
C.
III
D.
IV
E.
V
(96-IIA-27)
AL-MC-E&M / p.16
The diagram shows the circuit of an ideal transformer with a load connected to the secondary. Which of the
following is/are correct at the moment when switch S is closed?
36.
(1)
The magnetic flux in the soft iron core will be reduced.
(2)
The back e.m.f. in the primary will drop.
(3)
The primary current will increase.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(96-IIA-28)
In the above circuit, both the cell E and the inductor L have negligible resistance. The e.m.f. of E is 10 V, and the
resistors
R1 and R2 are of resistances 2  and 3  respectively. What will the current drawn from the cell
be
37.
(I)
at the moment when switch S is closed?
(II)
When the steady state is reached after closing switch S?
(I)
(II)
A.
2A
0A
B.
2A
2A
C.
2A
5A
D.
5A
0A
E.
0A
5A
(96-IIA-33)
AL-MC-E&M / p.17
Two uniform magnetic fields of equal magnitude but with one into paper and the other out of paper, are separated
on the two sides of the y-axis as shown. A wire is bent into a closed loop OABO, which is shaped as a quarter of a
circle. It is rotated uniformly in a clockwise direction about O on the plane of the paper. Which of the following
graphs best shows the variation of current, I, in the loop with time, t, in one revolution?
38.
(97-IIA-23)
The above figure shows a small coil, connected to a light beam galvanometer, placed in a region of uniform
magnetic field between the poles of a magnet. The plane of the coil is parallel to the pole faces. Which of the
following actions would produce a deflection of the galvanometer?
(1)
Moving the coil to and fro between the poles.
(2)
Moving the coil away from the region between the poles faces.
(3)
Rotating the coil about a diameter through an angle of 180 .
o
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
AL-MC-E&M / p.18
39.
(97-IIA-26)
A d.c. motor is connected to a source of constant voltage V. When rotating at a steady speed, the motor draws a
current I and the back e.m.f. developed in its armature coil is  . Which of the following statements is/are correct?
40.
(1)
The resistance of the armature coil is V/I.
(2)
The mechanical power developed is I  .
(3)
The back e.m.f.  increases with the speed of rotation.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(97-IIA-31)
A light rectangular wire frame ABCD moves with a uniform speed to the left across a region of uniform magnetic
field acting into paper. Which of the following is/are true at the instant shown in the figure?
41.
(1)
A current is flowing in the clockwise direction.
(2)
The electric potential at B is higher than that at C.
(3)
The side AD experiences a magnetic force acting to the right.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(98-IIA-26)
AL-MC-E&M / p.19
The figure shows a charged particle moving in a circle with constant speed v on a plane perpendicular to a
uniform magnetic field. Which of the following graphs represents the relation between the time T for the particle
to complete a circle and its speed v ?
42.
(98-IIA-27)
AL-MC-E&M / p.20
Two long, straight parallel conducting wires, each
carrying a current I, are separated by a distance r as shown. What is the magnetic field at a point P at the same
distance r from both wires?
( o = permeability of free space)
A.
B.
C.
D.
E.
43. (98-IIA-30)
o I
2r
to the left
3 o I
to the left
2r
o I
r
to the left
3 o I
to the right
2r
o I
2r
to the right
AL-MC-E&M / p.21
The above diagram shows a rectangular current-carrying coil ABCD in a uniform magnetic field between two
pole pieces. The magnetic field is perpendicular to the plane of the coil. Which of the following statements is/are
correct?
(1)
There is a magnetic force action on the side
BC of the coil.
(2)
The magnetic forces acting on the coil tend
to reduce its area.
(3)
44.
The coil will return quickly to its original vertical position when it is disturbed slightly.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(99-IIA-27)
Which of the following graphs correctly shows the variation of the magnetic flux density B along the axis of a
long solenoid carrying a steady current with its length l ?
45.
(99-IIA-29)
AL-MC-E&M / p.22
In the above circuit, a coil L of large inductance, a 2 V light bulb B, a switch S and a 2 V battery are connected in
series. A neon lamp is connected across L. Which of the following statements is/are correct upon the opening of
switch S?
46.
(1)
A large e.m.f. is induced across coil L.
(2)
The neon lamp lights up momentarily.
(3)
Light bulb B continues to light up until the neon lamp dies out.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(99-IIA-30)
The figure show a long straight wire carrying an a.c. current which lies on the plane of the paper. When a small
search coil is placed at B such that the plane of the coil is on the paper, the length of the trace on the CRO is 2 cm
(with the time base of the CRO switched off). If the search coil is moved to A, the length of the trace would be
47.
A.
0.5 cm
B.
1 cm
C.
2 cm
D.
4 cm
E.
8 cm
(99-IIA-31)
For which of the following does the force between two objects vary inversely as the square of the distance
between their centers?
(1)
Two equal masses joined by a rubber band under tension.
(2)
Two long straight parallel conducting wires carrying steady electric currents.
(3)
The earth and a satellite in its orbit.
AL-MC-E&M / p.23
48.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(99-IIA-35)
Two long, straight, parallel conducting wires P and Q are positioned as shown. The same current flows through
both wires and is directed into the plane of the paper. Point A, B and C on the plane of the paper are equidistant
from both wires where C is the mid-point between the wires. Which of the following statements is/are correct?
49.
(1)
The magnetic field strength at C is greater than that at A.
(2)
The directions of the magnetic field at A and at B are the same.
(3)
The magnetic field strength at B will increase if the current flowing in the wires increases.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(99-IIA-36)
A coil of metal wire is placed o a plane perpendicular to a uniform magnetic field. The coil is rotated through 180
˚
about a diameter as shown.
The total charge circulated in the coil due to the inducted current is independent of
50.
A.
the area of the coil.
B.
the flux density of the magnetic field
C.
the number of turns of the coil
D.
the resistance of the coil
E.
the time taken for the flux change.
(00-IIA-25)
AL-MC-E&M / p.24
Four parallel long straight conductors carrying currents of equal magnitude pass vertically through the four
corners of a square PQRS. The current is directed into paper in one conductor and is directed out of paper in the
other three conductors. Which of the following arrangement can produce a resultant magnetic induction at the
center O of the square in the direction shown?
Current into paper Current out of paper
51.
A.
B.
P
Q
Q,R,S
P,R,S
C.
R
P,Q,S
D.
S
P,Q,R
E.
It is impossible to produce a resultant magnetic induction at O in the direction shown.
(00-IIA-27)
A beam of charged particles passes undeflected through a region of crossed uniform electric and magnetic fields.
Which of the following must be common to the particles making up this beam?
A.
B.
C.
D.
E.
52.
(00-IIA-28)
When a simple motor rotating at a steady speed is suddenly jammed and comes to a stop, which of the following
statements is/are correct?
(1)
(2)
(3)
The rate of change of magnetic flux through the coil of the motor will be very large.
A large e.m.f. will be induced in the coil of the motor.
A large current will flow through the coil of the motor.
A.
B.
C.
D.
E.
53.
charge to mass ratio
velocity
mass
sign of charge
magnitude of charge
(1) only
(3) only
(1) and (2) only
(2) and (3) only
(1), (2) and (3)
(00-IIA-31)
A constant p.d. is applied to a solenoid. The variation of current I with time t is as shown. Which of the following
can be deduced from the shape of the graph?
A.
The solenoid has resistance as well as inductance.
AL-MC-E&M / p.25
54.
B.
The inductance of the solenoid decreases as time increases.
C.
The inductance of the solenoid increases as time increases.
D.
The e.m.f. induced in the solenoid is
E.
The e.m.f. induced in the solenoid is proportional to the rate of change of current.
proportional to the current.
(00-IIA-32)
In the above circuit, A and B are identical light bulbs and L is a pure iron-cored inductor. Which of the following
statements is/are correct?
55.
(1)
When switch S is closed, bulb A will light up first.
(2)
After switch S is closed for some time, A and B are equally bright.
(3)
When switch S is open, bulb A will go out first.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(01-IIA-2)
Which of the following pairs of forces is/are example(s) of action and reaction?
(1) The centripetal force keeping a satellite in orbit round the earth and the weight of the satellite.
(2) The air resistance acting on an object falling through the air with terminal velocity and the weight of the
object.
(3) The forces of attraction experienced by two parallel wires carrying currents in the same direction.
56.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(01-IIA-26)
Magnetic flux is measured in weber. Which of the following is/are equivalent to weber?
(1)
henry-ampere
(2)
volt-second
AL-MC-E&M / p.26
(3)
57.
tesla-metre
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(01-IIA-27)
Which of the following properties is NOT common to both electric and magnetic fields?
A. Both can be ‘shielded’ using suitable materials.
B. Both can exert attractive and repulsive forces.
C. Both can deflect moving charged particles.
D. Both can be represented by field lines of closed loops.
E. Both can store energy.
58.
(01-IIA-28)
The figure shows a light and flexible conducting loop C freely hung on a smooth horizontal rail. A bar magnet PQ
approaches the loop from the right. Which of the following descriptions about this process is correct?
A. If P is an N-pole, the loop will be repelled to the left and its area will increase slightly.
B. If P is a S-pole, the loop will be repelled to the left and its area will increase slightly.
C. If P is an N-pole, the loop will be attracted to the right and its area will decrease slightly.
AL-MC-E&M / p.27
D. No matter whether P is an N-pole or a S-pole, the loop will be repelled to the left and its area will
increase slightly.
E. No matter whether P is an N-pole or a S-pole, the loop will be repelled to the left and its area will
decrease slightly.
59.
(01-IIA-29)
Which of the following descriptions about a moving-coil meter is/are correct?
60.
(1)
It has a massive soft iron core to provide damping.
(2)
It has curved magnetic poles to assist in producing linear scale.
(3)
It has weak hair springs to increase the sensitivity.
A.
(1) only
B.
(3) only
C.
(1) and (2) only
D.
(2) and (3) only
E.
(1), (2) and (3)
(02-IIA-27)

A metal rod of length l is inclined at 60 to rail PQ as shown . It
is moved across a uniform magnetic field along the direction of
the two horizontal rails PQ and RS. If rod moves with a uniform
velocity v and the flux density of the field is B, the e.m.f. induced
in the rod is
A.
B.
C.
Blv
2
Blv
2Blv
3
D.
61.
3Blv
2
(02-IIA-28)
A circular frame and s square frame, made from the same type of insulated metal wires, are placed in a uniform
magnetic field as shown .When the flux density of the field is increased at a steady rate, the ratio of the
AL-MC-E&M / p.28
induced current in the circular frame to that in the square frame is
A. 1 : 1
B. 1 : 
C. : 4
D. 2 : 

62
(02-IIA-29)

Three long straight parallel wires P,Q and R carrying currents of the same magnitude are situated at the vertices of
an equilateral triangle as shown .The currents in wires P and R are directed out of the paper .Which of the flowing
indicates the direction of the force acting on wire P?
63.
A.
→
B.
↓
C.
↑
D.
↗
(02-IIA-30)
A steadily running motor draws a current of 2 A form a batery of e.m.f. 5 V. the internal resistance of the battery is
negligible. If the resistance of its armature coil is 0.5  , estimate the efficiency of the motor.
A.
60%
B.
70%
C.
80%
D.
90%
AL-MC-E&M / p.29
64.
(03-IIB-30)
In the above set-up, AB and CD are two parallel infinitely long wires 20 cm apart, carrying currents I 1 and I2
respectively, The magnetic flux density at the point P 10 cm from wire CD is zero. If I 2=0.6 A, which of the
following statements about I1 is correct?
65.
A.
0.2 A flows in the same direction as I2
B.
0.2 A flows in the opposite direction as I2
C.
1.8 A flows in the same direction as I2
D.
1.8 A flows in the opposite direction as I2
(03-IIB-31)
A charged particle enters a region of uniform magnetic field whose direction is normal to the initial velocity of the
particle. The subsequent path of the particle is as shown.
AL-MC-E&M / p.30
Which of the following is/are possible explanations to account for the shape of the path?
(1) The flux density of the magnetic field has decreased gradually.
(2) The charged particle ahs lost its charge gradually.
(3) The charged particle has lost its kinetic energy gradually.
A.
B.
C.
D.
(1) only
(3) only
(1) and (2) only
(2) and (3) only
66. (03-IIB-32)
In the figure , the dotted part represents a spherical metallic shell A of uniform thickness. The shell is neutral as a
whole. A small positively charged object B is placed inside the cavity of the shell but note exactly at its centre.
Positive and negative charges are then induced in the shell.
(Distribution of induced charges is note indicated.)
Which of the following statements is/are correct when electrostatic equilibrium is reached?
(1)
Positive induced charges are distributed uniformly on the outer surface of the shell.
(2)
The electric field at any point with in the cavity is zero.
AL-MC-E&M / p.31
(3)
67.
The electric potential at the outer surface of the shell is higher than that at its inner surface.
A.
(1) only
B.
(2) only
C.
(1) and (2) only
D.
(2) and (3) only
(03-IIB-33)
The efficiency of a transformer is always less than 100%. Which of the following is not a reason for this?
68.
A.
eddy current flowing in the iron core
B.
heat dissipation in the primary coil
C.
leakage of magnetic flux
D.
work done against the back e.m.f. induced in the primary coil
(03-IIB-34)
The figure shows a rectangular coil PQRS moving from left to right with a uniform speed across an insulated
metal wire in the plane of the coil. The wire carries a steady current I. Which of the following gives the correct
sequence for the direction of the current induced in the coil PQRS?
A.
Clockwise and then anticlockwise
B.
Anticlockwise and then clockwise
C.
Clockwise, then anticlockwise and finally clockwise again
D.
Anticlockwise, then clockwise and finally anticlockwise again
68. (04-IIA-26)
The Hall effect
(1) Provides evidence that the charge carriers in metals are negatively charged.
(2) Can be used to determine the density of free electrons in a metal
AL-MC-E&M / p.32
(3) Can be used to determine the flux density of the magnetic field due to an a.c. only.
Which of the above statements are correct?
A.
(1) and (3)only
B.
(1) and (2) only
C.
(2) and (3) only
D.
(1), (2) and (3)
69. (04-IIA-27)
For the relation
secondary voltge no. of turns in the secondary

to hold for a transformer, which of the following conditions
primary vo ltage
no. of turns in the primary
are necessary?
(1)
The flux linkage of the iron core is negligible.
(2)
The energy loss in the primary coil is negligible
(3)
The secondary coil is on open circuit.
A.
(1) and (3)only
B.
(1) and (2) only
C.
(2) and (3) only
D.
(1), (2) and (3)
70. (04-IIA-28)
The figure shows a secondary coil placed at one end of a solenoid, which is connected to an a.c. source. The
changing magnetic flux in the solenoid induces an alternating voltage in he secondary coil, which is connected to
CRO.
Which of the following changes wlll NOT affect the
amplitude of the induced voltage in the secondary coil?
A.
Increasing the frequency of the a.c. in the solenoid
B.
Increasing the number of turns on the secondary coil
C.
Placing the secondary coil in the middle of solenoid, without changing its orientation
D.
Replacing the solenoid with one of greater cross-sectional area while keeping the same current
AL-MC-E&M / p.33
71. (04-IIA-29)
Three long, parallel, straight current-carrying wires P,Q and R are placed in the same plane in air as shown.
If F is the force per unit length between two long,
parallel, straight wires paced a distance d apart and each carrying a current of 1 A, what is the net force per unit
length acting on the wire R shown?
E.
0
F.
F
G.
2F
H.
3F
72. (05-IIA-16)
\
AL-MC-E&M / p.34
73. (05-IIA-18)
74. (05-IIA-19)
AL-MC-E&M / p.35