JEE NEET Physics Question Bank - Magnetic Effect of Current and Magnetism

13 Magnetic Effect of Current and Magnetism

(1) Biot-Savart’s Law
Biot Savart’s Law is used to determine the magnetic field any point due to a current carrying
conductor

o o
P 0 I dl u r
I dB
4S r2
Idl T
P P0 dl sin T
dB
r2
and for entire conducting wire,
I
o o P 0 I dl sin T 
B ³d B 4S ³ r 2
n

o
T 0 or S sin T 0 ? B 0
T 90q sin 90q 1 ? B maximum
SI unit of B = Wbm–2 or Tesla
1 tesla = 104 Gauss.
Where P 0 = Magnetic permeability of vacuum
= 4 S u 107 T m A1 or Wb A 1 m1 or H m1 or N A2
(2) For conducting wire,

(A) For a wire of finite length

T1 T 2 P0 I
B
4 Sd
>sin T1  sin T2 @
d
P0 I
4Sd
>cos D1  cos D2 @
D1 D2
I I

(B) For a wire infinite length T1 T2 90

or D1 D2 0q

? BD I
P0 I
? B
2 Sd d

(C) For a wire half infinite length. T1 0 and T 2 90q

P0 I P0 I
0 1
4S d 4 Sd
B

322

(3) For Rings

r a o radius
a
x o distance of given point on axis from center.
0 x P

a2  x2 2
1
r

P 0 Ia 2
(A) For number of turn N 1; B 3
2 a 2  x2 2

P 0 NIa 2
(B) For number of turn N N ;B 3
2 a 2  x2 2

P 0 NI
(C) At center of ring x 0; B
2a

P 0 N Ia 2
(D) If x ! ! a ; B
2 x3

P 0 NI
(E) At a distance on axis equal to radius of ring. B 5
2 2. a

(F) The ratio of magnetic field at center of ring and at any point on axis of ring

§ x2 · 2
3

¨1  2 ¸
BCenter
BAxis © a ¹

(1) A copper rod carries a DC current. The magnetic field associated with the current will be ..........

(A) Only inside the rod (B) Only out-side the rod

(C) Both inside and outside the rod (D) Neither inside, nor inside the rod

(2) A wire carrying a current I is bent in to a circle of radius r as shown in figure. The net magnetic
field at center O of the circular loop is ...............

r
P0 2I P0 2I
0 (A) S 1 (B) S 1
4S r 4S r

I I (C) Zero (D) Infinite

323

(3) Magnetic field at point P situated at perpendicular distance D from one end of wire of length L
and carrying current I is

P0 I L2
P I P0 I
(A) 0 (B) (C) 4 SD (D) infinite
4 SL 4 SD L2  D2

(4) An equilateral triangle loop of length ‘a’ is carrying current I in anticlock wise direction. Magnetic
field produced at center of the triangle is .

9 P0 I P0 I 3P 0 I 5 2P0 I
(A) (B) (C) (D)
2S a 3 3S a 2S a 3S a

(5) An electric charge of 35 & is moving with speed 2 u106 ms 1 along a path shown in figure.
Then magnetic field produced at point P is 7.

P

G (A) Zero (B) 242.5
r
50 mm
(C) 2425 (D) 2524
q 35 F 600
I
G
v

(6) quadrant will behave like North pole.

Y
I
Second quadrant First quadrant

Xc X (A) First (B) Third
I
Third quadrant Forth quadrant (C) Second (D) Forth

Yc
(7) A current of 6 A passes through the wire shown in figure. Then magnitude of magnetic field at

point O is T. The radius of arc is 0.2 m. P0 4S u 107 TmA –1

(A) 1.41 u 104 (B) 1.41 u 105
O (C) Zero (D) 1.41 u 103

6A

(8) As shown in figure, current I passes through hexagon having side a. Magnetic field at the center
of it is .
324

P0 I 3P 0 I
(A) (B)
I a 3 3S a Sa

3 3P 0 I P0 I
(C) (D)
Sa 3S a
(9) On connecting a battery to the two ends of a diagonal of a square conducter frame of side a, the
magnitude of the magnetic field at the center will be .
P0 2P0 4P0 I
(A) zero (B) (C) (D)
Sa Sa Sa
(10) 108 T magnetic field produced at point P situated at 4 cm perpendicular to very long wire
carring current I. How much magnetic field will be produced at a distance 12 cm. perpendicular
to the same wire ?
(A) 1.33 u 10 8 (B) 1.11 u 104 (C) 3 u 103 (D) 9 u 102

(11) In hydrogen atom, an electron revolving in the orbit of radius 0.53A with speed of 6.6 u 1015
0

revolution per second. Magnetic field at the center B = T.
(A) 0.125 (B) 1.25 (C) 12.5 (D) 125
(12) Two linear conductors AOB and COD are mutually perpendicular. Currents passing through them
are I1 and I 2 respectively. Point P lies at perpendicular distance a from point 0 of ABCD plane.
Magnetic field intensity at point P is .
P0 P0 P0 P0
(A) I1  I 2 (B) I1  I 2 (C) I12  I 2 2 (D) I12  I 2 2
1/ 2 1/ 2

2S a 4S a 2S a 2S a
(13) Electric current of 5 A passes through A current carrying straight wire. A point lying at a distance
10 cm from wire on perpendicular bisector of wire, makes angle 60° with both ends of wire.
Then intensity of magnetic field arising at that point is T.
(A) 3 P 0 (B) 3.98 P 0 (C) 39.8 P 0 (D) Zero
(14) Magnetic field lines associated with a very long straight current carrying wire will be .
(A) Along the length of the wire (B) centripetal
(C) Circular in the plane perpendicular to straight wire (D) Hyperbola
(15) Which of the following graphs shows the variation of magnetic induction B o distance (r) from
very long straight current carrying wire ?

(A) (B) (C) (D)
B B B B

r r r r
325

(16) The magnetic field due to a straight conductor of unifrom cross section of radius a and carrying
steady current is represented by graph.
B B B B

(A) (B) (C) (D)

a r a r a r a r

Ans : 1 (C), 2 (B), 3 (C), 4 (A), 5 (C) 6 (B), 7 (B), 8 (B), 9 (A), 10 (A), 11 (C), 12 (C),
13 (B), 14 (C), 15 (B), 16 (A)

Ampere’s Circuital Law
The line integral of magnetic field on a closed curve (loop) in a magnetic field is equal to the

product of a algebraic sum of the electric current ¦I enclosed by that closed loop and the

permeability P 0 of vacuum.

v³ B˜ dl P0 ¦ I
o o
\

§ P0 I ·
Magnetic field inside the conductor at a distance r from the axis of wire is B ¨ 2S a 2 ¸ r , r  a
© ¹

N
Magnetic field at a point inside a solenoid of infinite length, B P0 nI where n
l

P 0 nI
Magnetic field at a point inside solenoid of finite length, B sin D1  sin D 2
2

§ N ·
Magnetic field produced in a toroid, B P0 ¨ ¸I
© 2S r ¹
P0 nI

(17) Two coplaner and concentric coils of 20 turns each having radii of 40 cm and 80 cm are carrying
current 0.4 A and 0.8 A in opposite direction respectively. The net magnetic field at the center is
T.

(A) 4 P 0 (B) 2 P 0 (C) P0 (D) P0
10 5
4 4
(18) When a steady current carrying straight wire turned into one circular loop, the magnetic induction at
the center of loop due to current is B. If the same wire is turned into n loops to make a circular
coil, the magnetic intensity at the center of this coil for same current will be .
(A) nB (B) n 2 B (C) 2nB (D) 2n 2 B

326

(19) If ratio of magnetic intensities at center and at distance x from center on axis of current carrying
circular ring of radius R is 8:1 then x = .
R 2R
(A) 3R (B) (C) 2 3 R (D)
3 3

(20) Magnetice field is B1 at centre of current carrying coil of radius a and B2 at a distance a on its

B1
axis from centre, then ratio B = .
2

(A) 2 :1 (B) 1 : 2 2 (C) 2 2 : 1 (D) 1 : 2

(21) Two concentric rings carry current I1 and I 2 . If the ratio of their radii is 1 : 2 and ratio of

I1
magnetic field at centre is 1 : 3 . Then I .
2

(A) (B) (C) (D)
1 1 1 1
4 6 2 3

(22) Current I passes through solenoid having radius a and length L. Magnetic field produced at the
end point of solenoid is

2P0 nIL P0 nIL 2 P 0 nIL
(A) (B) Zero (C) (D) L2  a 2
1
L a
2 2
2 L a 2 2 2

(23) Magnetic field at the mid point of axis of solenoid having radius 1.0 m and length 2.0 m
is .
P 0 nI P 0 nI P 0 nI
(A) (B) (C) 2 P 0 nI (D)
2 2 2 2

(24) Two similar coils are kept mutually perpendicular such that their centres coincide. At the centre,
what is the ratio of the magnetic field due to one coil and the resulant magnetic field by both
coils if the same current flows through them ?

(A) 1: 2 (B) 1: 2 (C) 2 :1 (D) 3 :1
(25) A wire is wound on solenoid having 10 A current capacity. If length of solenoid is 80 cm and
having cross section radius 3 cm. Then length of required wire is Take B 2T .

(A) 1.2 u 102 (B) 4.8 u 102 (C) 2.4 u 103 (D) 6 u 103

(26) Ampere’s circuital law is equivalent to .
(A) Bio Savart’s law (B) Coulomb’s law (C) Faraday’s law (D) Kirchoff’s law
(27) The dimensional formula of magnetic intensity B is .

(A) M1L2 A 1 (B) M1T 2 A1 (C) M 2 T A 2 (D) M 2 LT 2 A 1

327

(28) Which one is the correct graph between the magnetic induction (B) along the axis of current
carrying long solenoid and distance x from one end of solenoid ?
B B B B
(A) (B) (C) (D)

x x x x

Ans. : 17 (C), 18 (B), 19 (A), 20 (C), 21 (B), 22 (C), 23 (D), 24 (A), 25 (C), 26 (A), 27 (B)
28 (A)
l Force on a charged particle in magnetic field.

If a particle carrying a positive charge q and moving with velocity v enters in a magnetic field
B then it experiences a force F which is given by the expression.
o §o o·
q ¨ v u B¸
© ¹
F

?F Bqv sin T
If charge is negative
o §o o· § o o·
 q ¨ v u B¸ q ¨B u v ¸
© ¹ © ¹
F

\ F Bqv sin T
Force on charged particle will be zero
(1) If B 0
(2) If particle is neutral then q 0
(3) If charge particle is static then v 0
(4) If charge particle moving parallel or anti parallel to magnetic field then T 0 or S
l Lorentz Force : When the moving charged particle is subjected simultaneously to both electric
o o
field E and magnetic field B . So the Lorentz force acting on it

o ª o § o o ·º
q «E  ¨ v u B ¸»
¬ © ¹¼
F

mv p 2mK 1 2mv
l Cyclotron : Radius of circular path of charged particle. r
Bq Bq Bq B q

If charged particle accelerated by voltage V and obtain kinetic energy K then

p mv 2mK 2mqV

328

Angular frequancy of charged particle, Zc
Bq
m
2S m
Periodic time of charged particle, T
Bq
(29) A particle of mass m has an electric charge q. This particle is accelerated through a potential
difference V and then entered normally in a uniform magnetic field B. It performs a circular

motion of radius R. The ratio of its charge to the mass is . ( is also called
q q
m m
specific charge.)

(A) (B) (C) (D)
2V V VB mV
2 2
BR 2BR 2R BR
(30) A proton, a deuteron ion and an D - particle of equal kinetic energy perform circular motion normal
to a uniform magnetic field B. If the radii of their paths are rp , rd and rD respectively then
Here qd q p , md 2m p .

(A) rD rp  rd (B) rD rd ! rp

(C) rD ! rd ! rp (D) rD rd rp
(31) Maximum force acting on electron moving in magnetic field of 5 u 105 T with velocity
4 u 104 ms 1 is N.
(A) 1.6 u 1019 (B) 3.2 u 1019 (C) 1.6 u 1017 (D) 3.2 u 1017
(32) If Lorentz force acting on charged particle is zero and electric field is 5Vm –1 then
o o
|Bu v | .
(A) Zero (B) Infinite (C) 5 (D) 10
(33) Force acting on moving proton having velocity of 10 i ms  1 in magnetic field of 5 j T will be
.
(A) 5 u 1018 k (B) 2 u 1018 k (C) 8 u 1018 k (D) 10 u 1018 k
(34) A proton is moving perpendicular to a uniform magnetic field of 5 T with 2 MeV kinetic energy.
The magnetic force acting on proton is N.
(mp 1.6 u 1027 Kg , qp 1.6 u 1019 C )
(A) 8 u 1011 (B) 16 u 1011 (C) 8 u 1012 (D) 16 u 1012
o
(35) A proton having velocity v 2i  3 j m s 1 is moving in magnetic field of B
o
2i  3 j T .
Magnetic force acting on proton is N.
(A) 1.6 u 1019 (B) 9.1 u 1031 (C) Zero (D) infinite
(36) A particle having 2 C charge passes through magnetic field of 4k T and some uniform electric
field with velocity 25 j ms 1 . If the Lorentz force acting on it is 400 i N . The electric field in
this region is Vm1 .
(A) 200 i (B) 200 k (C) 100 i (D) 10 j

329

(37) A proton (mass = 1.67 u 1027 kg and charge = 1.6 u 1019 c ) enters perpendicular to a magnetic
field of intensity 2 T with a velocity 3.4 u 107 ms1 . The acceleration of the proton is
ms2
(A) 6.5 u 1015 (B) 6.5 u 1013 (C) 6.5 u 1011 (D) 6.5 u 109
(38) A deutron of kinetic energy 50 KeV is describing a circular orbit of radius 0.5 meter in a plane
o
perpendicular to magnetic field B . The kinetic energy of the proton that describes a circular orbit
o
of radius 0.5 meter in the same plane with the same B is KeV.
(A) 25 (B) 50 (C) 100 (D) 200
(39) Two electron having same velocities v and moves parallel to each other at distance r. The ratio
of magnetic force and electric force acting on them is .

v c v2 c2
(A) (B) (C) 2 (D) 2
c v c v
(40) Path of charged particle entering perpendicular to magnetic field will be .
(A) circular (B) linear (C) elliptical (D) parabolic

Ans. : 29 (A), 30 (A), 31 (B), 32 (C), 33 (C), 34 (D), 35 (C), 36 (C), 37 (A), 38 (C),
39 (C), 40 (A)

l Force acting on current carrying wire of length l placed in uniform magnetic field
o o o
F I l uB
o o
?F BIl sin T where q is angle between l and B .
l Force between two parallel current carrying conductors and seperated by a distance y.
o P0 I1 I 2 l
|F|
2S y

Force per unit length,

F P 0 I1 I 2
l 2S y

If conductors carry current in same direction, then the force between them will be attractive.
If conductors carry, current in opposite direction, then force between them will be repulsive.
o o o
l Torque acting on current carrying loop, suspended in a uniform magnetic field, 0u%
o o
where M NI A = Magnetic dipole linked with coil.

(41) The magnetic dipole moment of a current carrying loop is independent of .
(A) Magnetic field in which it is lying (B) Number of turns
(C) Area of the loop (D) Current in the loop
330

(42) A rectangular loop carrying current I is situated near a long straight wire such that the wire is
parallel to one of the sides of the loop and is in the plane of the loop. If a steady current I is
established in wire as shown in figure, the loop will .
I

I

(A) Rotate about an axis parallel to the wire (B) Move away from the wire or towards right
(C) Move towards the wire (D) Remain stationary
(43) A conducting circuler loop of radius r carries a constant current I. It is placed in a uniform
o o
magnetic field B such that B is perpendicular to the plane of the loop. The magnetic force
acting on the loop is .
o o o
(A) Ir B (B) 2S rI B (C) zero (D) S r 2 IB
(44) A circular coil of radius 4 cm and of 20 turns carries a current of 3 ampere. It is placed in a
magnetic field of intensity of 0.5 T. The magnetic dipole moment of the coil is
ampere m2
(A) 0.15 (B) 0.30 (C) 0.45 (D) 0.60
(45) Two thin long parallel wires seperated by distance b are carrying current I amp each. The
magnitude of the force per unit length exerted by one wire on the other is .
P0I 2 P0I 2 P0 I P0 I
(A) (B) (C) (D)
b 2
2S b 2S b 2S b2
(46) A close loop PQRS carrying a current is placed in a uniform magnetic field. If the magnetic force
on segment PS, SR and RQ are F1 , F2 and F3 respectively and are in the plane of the paper and
along the directions shown, the force on the segment QP is .
Q
P
(A) F3  F1  F2 2 (B) F3  F1  F2
2
F3

(C) F3  F1  F2 (D) F3  F1  F2 2
F1 2

S R
F2
(47) As shown in the figure, two very long straight wires are kept parallel to each other and 2A
current is passed through then in the same direction. In this condition, the force between them is
F. Now if the current in both of them is made 1A and direction are reversed in both, then the
force between them .
(A) Will be and attraction
F
4

(B) Will be and repulsive
F

2A
2
2A 1A 1A
(C) Will be and attractive
F
2
first
(D) Will be and repulsive
F
4

331

(48) As shown in the figure 20 A, 40 A and 60 A current are passing through very long straight wires
P, Q and R respectively in the direction shown by the arrows. In this condition the direction of
the resultant force on wire Q is .

(A) towards left of wire Q
(B) towards right of wire Q
20 A 40 A 60 A (C) normal to the plane of paper.
(D) in the direction of current passing through Q
P Q R
(49) As shown in the figure, a straight wire PQ of length 2 m carrying 2 A current is placed parallel
to a very long wire at a distance of 2 m. Find the force acting on wire PQ. If the current passing
through the long wire is also 2 A.

Q
(A) 6 u 107 N (B) 16 u 107 N
I1 4 A I2 4 A
y=4m (C) 16 u 108 N (D) Zero

P

(50) A conducting wire of 4 m length is used to form circular loop. If it carries a current of 1.0 A it’s
magnetic dipole moment will be = Am2

S S 4
(A) 2S (B) (C) (D)
2 4 S

(51) Dipole moment of a coil is 2i  3 j  5k . If the coil is suspended in the uniform magnetic field

having magnitude 5kT torque acting on it will be = .
(A) 35 (B) 117 (C) 25 (D) 135
(52) An electron moves with a constant speed v along a circle of radius r. It’s magnetic moment will
be (e is the charge of electron)

(A) e v r (B) (C) S r 2 v (D) 2S ev
evr
2

(53) A circular coil having N turns is made from a wire L meter long. If a current of I is passed
through this coil suspended in a uniform magnetic field of B tesla, the maximum torque that can
act on this coil = .

BIL2 BIL2
(A) (B) zero (C) (D)
ILB
2S N 4S N 8S 2 N

332

(54) 1 A current carrying circular loop having radius 20 cm is kept in XY plane as shown in the figure
Torque acting on loop is Nm.
Y o
(A) 0.15 (B) 0.25
B 2T

(C) 0.35 (D) 0.55
X
I

(55) As shown in figure a rectangular coil having one turn is kept in uniform magnetic field of

j T . Torque acting on it will be Nm.
0.05 
2
Z

0.5 A (A) 11.32 u 104 k (B) 22.64 u 104 k

0.08 m (C) 5.64 u 105 k (D) Zero
I
Y
X 0.04 m

(56) A loop carrying current I lies in the XY plane as shown in the fig. The unit vector k is out ward
and perpendicular to the plane of the paper. The magnetic moment of the current loop is
.
Y

§S · 2 
(A) I a 2 k (B) ¨  1¸ a I k
a X ©2 ¹
0
§S · 2 
(C)  ¨  1¸ a I k (D) 2S  1 a 2 I k
©2 ¹

(57) Straight conducting wire of length 0.5 m and carrying current 1.2 A is placed perpendicular in
uniform magnetic field of 2 T. Magnetic force acting on it will be N.
(A) 2.4 (B) 1.2 (C) 3.0 (D) 2.0
(58) Two very long parallel wire seperated by 10 cm and carrying current 10 A in same direction.
Force acting on unit length of one wire due to other will be N.
(A) 2 u 104 N Attractive (B) 2 u 104 N Repulsive
(C) 2 u 107 N Attractive (D) 2 u 107 N Repulsive
(59) A small coil of N turns has an effective area A and carries a current I. It is suspended in
o
a horizontal magnetic field B such that its plane is perpendicular to B. Find the work done
in rotating it by 180q about the vertical axis .

(A) NIAB (B) 2 NIAB (C) (D) 4 NIAB
2NIA
B
333

(60) A square coil 20 cm ´ 20 cm has 100 turns and carries a current of 1 A. It is placed in a
uniform magnetic field B = 0.5 T with the direction of magnetic field parallel to the plane of the
coil. The magnitude of the torque required to hold this coil in this poisition is Nm.
(A) zero (B) 2 (C) 10 (D) 40

Ans. :41 (A), 42 (C), 43 (C), 44 (B), 45 (B), 46 (D), 47 (A), 48 (A), 49 (B), 50 (D),

51 (B), 52 (B), 53 (C), 54 (B), 55 (C), 56 (B), 57 (B), 58 (A), 59 (B), 60 (B)

Galvanometer
Use to detect and measure small electric currents. If the coil becomes steady after a deflection q,
Deflecting torque = Restoring torque.
NIAB KT

I ( K o effective torsional constant of the spring)
K
?I
NBA
?IDI

I
Current sensitivity Si
NBA
I K
The current sensitivity of a galvanometer is definned as the deflection produced in the
galvanometer per unit current flowing through it.
Ammeter
Use to measure electric current
The small resistance joined in parallel to a galvanometer to convert it into an ammeter is called a
sShunt.

GI g
Shunt = S I  Ig

To convert a galvanometer’s rangh by n time I necessary shunt S
G
nI g
n 1

§ G ·
Current passing through shunt I s I¨ ¸
© G S¹

§ S ·
Current passing through galvanometer I g I¨ ¸ where, I o net current
©SG ¹
Voltmeter
Use to measure p.d. between two ends of conductor
To convert a galvanometer into a voltmeter, a resistance of high value is joined in series with it.

G
V
Rs
Ig

334

To increase voltage capacity by n times, necessary series resistance R s (n  1) G
Voltage sensitivity : Sv
Voltage sensitivity of a galvanometer is defined as the deflection produced in the galvanometer
per unit voltage applied to it.
I NBA
Sv
V KR
(61) Resistance of galvanometer is G.. If shunt required to make its range n times is S, then
n= .

(A) (B) 1  (C) 1  (D)
G G G S
S S S G

(62) Resistance of galvanometer is G.. If series resistance required to make its voltage capacity n
times is Rs, than Rs = .

(A) Gn (B) (n–1) G (C) (n+1) G (D)
G
n 1
(63) Resistance of galvanometer is G. What will be resistance of voltmeter after making its voltage
capacity n times ?

(A) nG (B) (n–1) G (C) (n+1) G (D)
G
n 1
(64) Resistance of DC ammeter is 10 : and its current capacity is 20 mA. Resistance required to
convert it in to volt meter measuring 3V p.d. is :.
(A) 110 (B) 120 (C) 130 (D) 140
(65) 0.5 % of the total current in ammeter passes through galvanometer. If resistance of galvanometer
is G, resistance of ammeter is

(A) (B) (C) 119 G (D) 200 G
G G
200 104

(66) What will be the shunt required to pass 10 % of the main current through moving coil
galvanometer having resistance 99 : :.
(A) 10 : (B) 9.9 : (C) 9 : (D) 11 :
(67) A galvanometer of resistance 25 : giving full scale deflection for a current of 10 miliampere is
to be converted into a voltmeter of range 100 V by connecting a resistance of ‘R’ in series with
galvanometer. Value of resistance R is :.
(A) 10,000 (B) 10,025 (C) 975 (D) 9975
(68) An Ideal battery of 100 V is connected in series to a 20 : resistor. A galvanometer of 5 : is
used to measure current in the circuit. Error in measurement will be .
(A) 0.5 A (B) 1 A (C) 2 A (D) 3 A

335

(69) A galvanometer of resistance 200 : is connected to a shunt of 20 : to form an ammeter. On
connecting this ammeter to a battery of 10 V and a resistor of 4 : in series, A
electric current passes through ammeter.

(A) (B) (C) (D)
55 77 122 177
122 55 55 22
(70) On connecting a shunt of 12 : in parallel to a galvanometer, its deflection decreases from 50
division to 20 division. Then resistance of galvanometer is :.
(A) 18 (B) 26 (C) 30 (D) 36
(71) Resistance of a galvanometer is G. On passing electric current Ig, it shows full scale deflection. A
shunt S1 , is required to convert this galvanometer in to an ammeter of range 0 to I. If shunt S2 is

required to convert this galvanometer into an ammeter having range 0 to 2I, then S =
S1
.
2

2I  I g 1 § I  Ig ·
(A) (B) 2 ¨ 2 I  G ¸ (C) 2 : 1 (D) 1 : 1
I  Ig © ¹
(72) A galvanometer of resistance 50 : shows full scale deflection of 30 division when it is
connected in series with 3 V battery and 2950 : resister. To obtain 20 division deflection for
same galvanometer, the value of series resistor required is :.
(A) 4450 (B) 5050 (C) 5550 (D) 6050
(73) A galvanometer has resistance of 15 : and gives full scale difflection for 4 mA current. To
convert it into a ammeter of range 0 to 6 A, .
(A) 10 m : resistance connected in parallel with galvanometer
(B) 10 m : resistance connected in series with galvanometer
(C) 1 : resistance connected in parallel with galvanometer
(D) 0.1 : resistance connected in series with galvanometer
(74) A voltmeter of resistance 1000 : giving full scale deflecation for a current of 100 mA is to be
converted into an ammeter of range 1A. The value of shunt S is :.
(A) 10000 (B) 9000 (C) 222 (D) 111

(75) If a galvanometer of resistance 25 : is shunted by 2.5 : , then
Ig
I
I g = current passing through galvanometer, I = net current

(A) (B) (C) (D)
1 1 3 4
11 10 11 11
(76) The ( o T ) graph for a current carrying coil is .
t
(A) (B) (C) (D)

0 90 180 90 180 90 180 90 180
T T T T

336

Ans. : 61 (C), 62 (B), 63 (A), 64 (D), 65 (A), 66 (D), 67 (D), 68 (B), 69 (A), 70 (A),
71 (A) 72 (A), 73 (A), 74 (D), 75 (A), 76 (A)
Magnetism and Matter :
o
Magnetic dipole moment of current carrying loop m IA

Pole strength of magnet p where F = Force, B = magnetic field
F
B


Magnetic dipole moment of bar magnet mb 2 Pl direction of mb is from the south pole to the
JG G

north pole
P 0 p1 p2
The magnitude of force of attraction or repulsion between two magnetic poles F
4S r 2
The force acting between two small bar magnet lying on same axis x distance apart from
3P 0 m1m2
each other F
2 Sx 4

o 2P0 mz
The magnetic field at a point z on the axis from the center of bar magmet B( z ) l
m
4S z  l 2 2 2

o 2P 0 m l
if z !!! l , the value of B ( z ) m
4 Sz 3
The magnetic field on the equaterial point at a distance y from the centre of dipole of a bar magnet
o P0 m l
B ( y) 3
m
4S y  l 2 2 2

o
if y !! l , the value of B ( y )
P0 m l
m
4 Sy 3

The torque acting on a magnetic dipole of magnetic moment m in uniform magnetic field ( B ) :
o
o o o
W muB

The periodic time, T 2S I
mB
o o
The potential eneregy, U m<B mBcos T
o
The work done on the magnetic dipole placed in uniform magnetic field ( B ) and rotating by
(displacing) angle T

W mB 1  cosT
mB cosT1  cos T 2
mB cosT 2  cos T1

337

Gauss’s law for magnetic field :

The net magnetic flux associated with closed surface, v³ B < d a
o o
0

o
(77) A bar magnet of length l, pole strength p and magnetic moment m is split into two equal pieces

each of length . The magnetic moment and pole strength of each piece is respectively
l
2
and .
o p o o
o
(A) m, (B) (C) (D) m, p
m m p
,p ,
2 2 2 2
(78) When a bar magnet is cut into two equal parts parallel to the length which of the following
physical quantity does not change ?
(A) pole strength of poles (B) magnetic dipole moment
(C) intensity of magnetic field (D) moment of inertia
(79) A large magnet is broken into two pieces. so that their lengths are in the ratio 2:1, the pole
strengths of the two parts will have ratio .
(A) 1 : 2 (B) 2 : 1 (C) 4 : 1 (D) 1 : 1
(80) The unit of pole strength of magnet is (where Q is charge and v is velocity)

v 1
(A) Qv (B) (C) Q (D) Qv
Q
v
(81) Point A and B lie on axis of bar magnet of length 3 cm at a distance 24 cm and 48 cm from
center of bar magnet on opposite sides. Ratio of magnetic field at point A and B is .
(A) 8:1 (B) 4:1 (C) 3:1 (D) 1: 2 2
(82) If magnetic field at two points lying on equatorial line and axis of small bar magnet are same
then ratio of its distance from center of magnet is .
(A) 2–3 (B) 23 (C) 2 13 (D) 2 13
(83) Force acting on north pole of magnet of polestrength 3200 Am. lying 10 cm away from south
pole of bar magnet of polestrength 40 Am is N.
(A) –1.28 (B) 1.28 (C) 1.28 u 107 (D) 1.28 u 107

(84) A magnet of magnetic moment 0.1 Am2 is placed in a uniform magnetic field 0.36 u 104 T . The
force acting on its each pole is 1.44 u 104 N . The distance between two poles would be
cm.
(A) 1.25 (B) 2.5 (C) 1.8 (D) 5.0
(85) The magnetic dipole moment of steel wire of length L, is m. It is bent from the middle and
arranged as 600 . So the new magnetic dipole moment will be .

(A) (B) (C) m (D) 2 m
m m
2 2
338

(86) A straight wire of length l and magnetic dipole moment m is bent in form of a semi circle. Hence
new magnetic dipole moment is .

(A) (B) (C) (D)
m 2m 3m 4m
S S S S

(87) A straight wire of length l and magnetic dipole moment m is bent in the form of a circle. Its two
ends makes angles 600 at the centre. Hence new magnetic dipole moment is .

(A) (B) (C) (D)
m 2m 3m 4m
S S S S

(88) Magnetic field of current carrying coil at a distance 10 cm on axis from centre is 10 4 T .

If diameter of coil is 1 cm then magnetic dipole moment will be Am2 .
(A) 0.5 (B) 1.0 (C) 1.5 (D) 2.0

(89) A closely would solenoid of 6 cm, having 10 turns cm–1 and area of cross-section 3 u 104 m 2

carries a current of 1.0 A. The magnetic moment m of the solenoid is Am2 .

(A) 1.8 u 102 (B) 0.3 u 102 (C) 1.6 u 102 (D) 3.6 u 102

(90) The dimensional formula of magnetic field (B) in MLT and C (Coulomb) is given as .
(A) M1T 1 C 1 (B) M1T 2 C1 (C) M1L1T 1C 1 (D) M 1T 2 C 2

(91) Force between two identical bar magnets whose center are 4 cm apart is 4.5 N when their axis
are in the same line. If seperation is increased to 24 cm, the force between them is N.

(A) 0.37 u 102 (B) 0.6 (C) 1.2 (D) 2.4

(92) Two idential bar magnets with length 10 cm and mass 50 g. are arranged freely with their like
poles facing each other in a inverted vertical glass tube. The upper magnet hangs in the air above
the lower one so that the distance between the nearest pole of the magnet is 3 mm. pole strength
of the poles of each magnet will be Am.

S (A) 6.64 (B) 33.2
(C) 11.1 (D) 99.6
N
N

S

(93) Two short magnets of equal dipole moments M are arranged perpendicularly such that their
centres coincide (fig.) The magnitude of the magnetic field at a distance d from the centre on the
bisector of the right angle is

339

m
P
N
(A) (B)
om o 2m
4 d3 4 d3

S 0 N m
(C) (D)
o2 2m o 2m
4 d3 4 d3

S

(94) Two short magnets of magnetic moment 1000 Am2 are placed as shown at the corners of a
square of side 10 cm. The net magnetic induction at P is T.

1

(A) 0.1 (B) 0.2

(C) 0.3 (D) 0.4

P
2
(95) Two magnets A and B are identical and are arranged as shown in the figure. Their length is
negligible in comparison to the separation between them. A magnetic needle is placed between
the magnets at point P which gets deflected through an angle T under the influence of magnets.
The ratio of distance d1 and d2 will be .

T
(A) (B) 2 tan T
1/ 3 1/ 3
P
2 tanT

(C) (D)
1/3 1/3
2cotT 2cotT
d1 d2

(96) A loop of radius 4 cm and 20 turns carries a current 3 A. If it is placed in magnetic field of 0.5
T, the potential energy of dipole in most stable position is J.
(A) –0.15 (B) 0.15 (C) –1500 (D) 1500
(97) A short bar magnet placed with its axis at 30° with a uniform external magnetic field of 0.25 T
experience a torque of 4.5 u 102 Nm . Magnetic moment of the magnet is JT 1

(A) 0.18 (B) 0.36 (C) 0.54 (D) 0.72
(98) A bar magnet is held perpendicular to a uniform field. How much angle by which it is should be
rotated so that the value of torque becomes half of the original value of torque .
(A) 300 (B) 450 (C) 600 (D) 750

340

(99) A bar magnet with magnetic dipole moment m rotates and makes an angle T with the intensity
of magnetic field H, the work done in this process is .
(A) mH cos T (B) mH (1  cosT ) (C) mH sin T (D) mH (1  sin T )

(100) A magnet of magnetic dipole moment 5.0 Am 2 is lying in a uniform magnetic field of 7 u 104 T

such that its dipole moment vector makes an angle of 300 with the field. The work done in
increasing this angle from 300 to 45 is about J.
0

(A) 5.56 u 104 (B) 24.74 u 104 (C) 30.3 u 104 (D) 5.50 u 103
(101) A circular coil having 50 turns and radius 4 ´ 10–2 m carries a current of 2 A. It is placed in
uniform magnetic field of intensity of 0.1 Wbm–2. The work done to rotate the coil from the
equillibrium position by 180q is J
(A) 0.1 (B) 0.2 (C) 0.3 (D) 0.4
(102) The moment of inertia of magnetic needle is 8 u 106 Kgm2 and its magnetic dipole moment is

101 Am2 . The value of magnetic field if it performs 10 oscillations in ten second is T.

(A) 3.15 u 103 (B) 1.35 u 103 (C) 3.15 u 105 (D) 1.35 u 105
(103) The period of oscillation of two magnets in the same field are in the ratio of 2:1. If their moment
of inertia are equal, the ratio of their magnetic moments is .
(A) 1 : 2 (B) 1 : 4 (C) 2 : 1 (D) 4 : 1
(104) The period of oscillation of a magnet is 2 sec. When it is remagnetised so that the pole strength
is 4 times, its period will be sec.
(A) 1 (B) 2 (C) 4 (D) 8
(105) Rate of change of torque t with deflection T is maximum for a magnet suspended freely in a
o
uniform magnetic field of induction B when
(A) T 0 (B) T 450 (C) T 600 (D) T 900

(106) A magnet freely suspended in a vibration magnetometer is heated so as to reduce it’s magnetic
moment by 36 % by doing this, its perrodic time .
(A) Increase by 36 % (B) Increase by 25 % (C) Decrease by 25 % (D) Decrease by 64 %

(107) Two magnet are held together and allowed to oscillete in earth’s magnetic field. With like poles
together and unlike poles together periodic time are 4 s and 6 s respectively. The ratio of their
magnetic moment is .
(A) 6 : 4 (B) 30 : 16 (C) 2.6 : 1 (D) 1.5 : 1
Ans. : 77 (B), 78 (C), 79 (D), 80 (A), 81 (A), 82 (D), 83 (B), 84 (B), 85 (B), 86 (B),
87 (C), 88 (A), 89 (A), 90 (A), 91 (A), 92 (A), 93 (C), 94 (A), 95 (C), 96 (A),
97 (B), 98 (C), 99 (B), 100 (A), 101 (A), 102 (A), 103 (B), 104 (A), 105 (A),
106 (B), 107 (C)

341

l If B is the magnetic field at any place on the earth
Bh Bcos T
Its horizontal component B h Bcos T I

Its vertical component Bv Bsin T
Bv Bsin T o
Where I o Angle of dip. B

Here B Bh 2  Bv 2

tan T
Bv
Bh

l Magnetic susceptibility :

Fm Where_ M o Intensity of magnetization
M
H

H o Magnetic intensity

l Permeability

P P 0 (1  F m )

? Pr 1  Fm
P
P0 Where Pr o Relative permoability

According to Curie’s Law

cP 0
Fm ? Fm D
M 1
H T T

(108) The magnetic dip angle at a certain place where the horizental and vertical components of earth’s
magnetic field are equal is .
(A) 0o (B) 30o (C) 45o (D) 90o
(109) At a place on Earth, the horizontal component of Earth’s magnetic field is 3 times its vertical
component. The angle of dip at this place is .
(A) 0o (B) 30° (C) 45° (D) 90°
(110) The angle of dip at a given place in magnetic merridian is 30o , then the angle of dip in the plane
perpendicular to the magnetic meridian is rad.

S S S
(A) 0 (B) (C) (D)
3 6 2
(111) At a certain place on the earth, the horizontal component of magnetic field is 73.2 % more than
the vertical component. The angle of dip at this place would be .
(A) 30o (B) 45o (C) 60o (D) 90o

342

(112) The magnetic dip angle at two places are 30o and 45o . Calculate ratio of horizontal components
of earth’s magnetic field at the two places.
(A) 3: 2 (B) 1 : 2 (C) 1 : 2 (D) 1 : 3

(113) A small bar magnet of magnetic dipole moment 1.6 Am2 is placed in a magnetic meridian in such
a way that its north pole remains in north direction. At this time, if neutral point is obtained at
distance 20 cm, then horizental component of earth magnetic field Bh T.

(A) 1 u 105 (B) 2 u 105 (C) 3 u 105 (D) 4 u 105

(114) The Earth’s magnetic field at some place on magnetic equator of Earth is 0.4 u 104 T . Estimate
the magnetic dipole moment of the Earth. Consider the radius of earth at that place to be
6400 Km.
(A) 1.05 u 1020 Am2 (B) 1.05 u 1021 Am2 (C) 1.05 u 1022 Am2 (D) 1.05 u 1023 Am2
(115) A bar magnet is placed with its south pole towards geographic north. The neutral point is situated
at distance of 40 cm from the center of the magnet. The length of the magnet is 20 cm.
The horizontal component of the earth’s magnetic field is 3.2 u 105 T . The pole strength of the
magnet is Am.
(A) 5 (B) 10 (C) 25 (D) 45
(116) Two short bar magnets of length 1 cm each have magnetic moments 1.20 Am2 and 1.00 Am2
respectively. They are placed on a horizontal table parallel to each other with their N poles
pointing towards the south. They have a common magnetic equator and are seperated by a
distance of 20 cm. The value of the resultant horizontal magnetic induction at the mid-point of the
line joining their centers is T. Bh 3.6 u 105 T .

(A) 3.5 u 104 (B) 5.8 u 104 (C) 3.6 u 105 (D) 2.56 u 104
(117) Relative permeability of substance is 0.075. Its magnetic susceptibillity is .
(A) 0.925 (B) – 0.925 (C) 1.075 (D) –1.075
(118) A toroid wound with 100 turns/m of wire carries a current of 3A. The core of toroid is made of
iron having relative magnetic permeability P r 5000 under given conditions. The magnetic field

inside the iron is T. Take 0  ×10-7 TmA -1

(A) 0.15 (B) 0.47 (C) 1.5 u 102 (D) 1.88

(119) A magnet of 1.2 Am2 magnetic dipole moment having dimension of 0.15 m u 0.02 m u 0.01 m .

Then intensity of magnetization M is Am1 .

(A) 10 4 (B) 2 u 104 (C) 4 u 104 (D) 8 u 104

(120) A magnet has coercivity of 3 u 103 Am 1 . It is kept in a 10 cm long solenoid with a total of 50
turns. How much current has to be passed through the solenoid to demagnetize it ?
(A) 0.1 A (B) 0.6 A (C) 6 A (D) 10 A

343

(121) A magnetic field of 1600 Am1 produces a magnetic flux 2.4 u 105 Wb parallel to length of an iron

bar of cross sectional area 0.2 cm2 . The susceptibillity of iron bar will be .
(A) 298 (B) 596 (C) 1192 (D) 1788
(122) The susceptibillity of a paramagnetic substance at 73o C temperature is 6 u 103 then the
suseptibillity at 173q C temprature will be .
(A) 1.2 u 102 (B) 1.8 u 103 (C) 3 u 103 (D) 4.5 u 103

(123) A magnet in the form of a cylindrical rod has a length of 5 cm and a diameter of 2 cm. It has a
uniform magnetization of 5 u 103 Am 1 . Its net magnetic dipole moment is JT 1 .

(A) 7.85 u 102 (B) 8.75 u 102 (C) 5.78 u 102 (D) 7.58 u 102
(124) A magnetic needle vibrates in the vertical plane perpendicular to the magnetic meridian. The time
period of vibration is found to be 2 sec. The same needle is then allowed to vibrate in the horizontal
plane and the time period is again found to be 2 sec. Then the angle of dip is .
(A) 0o (B) 30° (C) 45o (D) 90o
(125) A bar magnet suspended in earth magnetic field and oscillating in horizontal plane with periodic
time T. If a wooden bar having moment of inertia equal to bar magnet is tied with bar magnet
then periodic time of system will be .

(A) (B) (C) (D)
T T T
3
2T
2 2

(126) A bar of iron has size of 5cm u 1cm u 1cm and density of 7.78 u 103 kgm3 . If each atom of iron
has atomic dipole moment of 1.8 u 1023 Am2 . Then magnetic dipole moment of iron in saturation
magnetization state will be Am2 .
(A) 4.75 (B) 5.74 (C) 7.54 (D) 17.54
(127) Two magnet of equal dipole moment are arranged perpendicularly at their center. The periodic
time of oscillation of system at anywhere on earth is T. Periodic time of each magnet will be
.
(A) (B) 2 4 T (C) 2 14 T (D) 2 3 T
1 1
2T

(128) The graph of susceptibility o temperature for a diamagnetic substance is .
(A) (B) (C) (D)

F F F F

0
0 0 0
T T T T

344

(129) The most appropriate magnetization M versus magnetising field H curve for a paramagnetic
substance is .

M C
(A) A (B) B
A
(C) C (D) D
H
E
D

(130) The F o T1 graph for an alloy of paramagnetic nature is shown in fig. The Curie constant is K.
c

(A) 57 (B) 67

(C) 77 (D) 97

1
1 3 1 T
10 K
T

Ans. : 108 (C), 109 (D), 110 (D), 111 (A), 112 (A), 113 (B), 114 (D), 115 (D), 116 (D),
117 (B), 118 (D), 119 (C), 120 (B), 121 (B), 122 (A), 123 (A), 124 (C), 125 (C),
126 (C), 127 (C), 128 (D), 129 (A), 130 (A)

Assertion - Reason type Question :

Instruction : Read assertion and reason carefully, select proper option from given below.

(a) Both assertion and reason are true and reason explains the assertion.

(b) Both assertion and reason are true but reason does not explain the assertion.

(c) Assertion is true but reason is false.

(d) Assertion is false and reason is true.

(131) Assertion : Cyclotrom does not accelerate electron

Reason Ñ Mass of the electron is very small.
(A) a (B) b (C) c (D) d

(132) Assertion : The magnetic field produced by a current carrying solenoid is independent of its
length and cross sectional area.

Reason Ñ The magnetic field inside the solenoid is uniform.
(A) a (B) b (C) c (D) d

345

(133) Assertion : A circular loop carrying current lies in xy plane with its center at origin has a
magnetic flux in negative Z-axis
Reason Ñ Magnetic flux direction is independent of the direction of current in the conductor.
(A) a (B) b (C) c (D) d
(134) Assertion : A direct current flowing through a metalic rod produces magnetic field only outside
the rod.
Reason Ñ There is no flow of charge carriers inside the rod.
(A) a (B) b (C) c (D) d
(135) Assertion : The poles of a magnet can never be seperated.
Reason Ñ Atoms themselves are magnets.
(A) a (B) b (C) c (D) d
(136) Assertion : When the radius of a circular wire carrying current is doubled, its magnetic moment
becomes four times.
Reason Ñ The magnetic moment of the loop depend on the area of loop.
(A) a (B) b (C) c (D) d
(137) Assertion : Steel is not attracted by a magnet
Reason Ñ Steel is not a magnetic substance.
(A) a (B) b (C) c (D) d
(138) Assertion : The force between two small bar magnets lying on the same axis is inversely
proportional to square of distance between them.
Reason Ñ The force between two poles of a magnet is inversely proportional to the square of
the distance between them.
(A) a (B) b (C) c (D) d
Asn. : 131 (A), 132 (B), 133 (C), 134 (D), 135 (A), 136 (B), 137 (C), 138 (D)
Comprehension Type Questions :
Paragraph -I Read the following paragraph and give the answers to the questions

A B

a

I 300
O

b D
C
A current loop ABCD is kept on the plane of the paper as shown in the figure. The arcs BC
(radius = b) and DA (radius = a) of the loop are joined by two straight wire AB and CD.

346

A steady current I is flowing in the loop. Angle made by AB and CD at the origin O is 30 . Another
o

straight thin wire with steady current I, flowing out of the plane of the paper, is kept at the origin.
(139) The magnitude of the magnetic field (B) due to arc AD at the origin ‘O’ is .
P0 I P0 I P0 I
(A) zero (B) (C) (D)
24a 4S a 12S a
(140) The magnitude of the magnetic field (B) due to the arc BC at the origin ‘O’ is .
P0 I P0 I P0 I
(A) zero (B) (C) (D)
24b 4S b 12S b
(141) The magnitude of the magnetic field (B) due to the loop ABCD at the origin O is .
P0 I § b  a · P0 I § b  a · P0 I § b  a ·
(A) ¨ ¸ (B) ¨ ¸ (C) ¨ ¸ (D) zero
2S © ab ¹ 24 © ab ¹ 4S © ab ¹

(142) Due to the presence of the current I at the origin, .
(A) the forces on AB and DC are zero
(B) the forces on AD and BC are zero

I1 I ª º
(C) the magnitude of the net force on the loop is given by « 2 ba  ab »
4 ¬ 3 ¼

P 0 II1
(D) the magnitude of the net force on the loop is given by ba
24 ab
Paragraph -II
Advanced countries are making use of powerful electromagnets to move trains at very high
speed. These trains are called Maglev trains (abbreviated from magnetic levitation.) These trains
float on a guideway and do not run on steel rail tracks.
Insteand of using an engine based on conventional fuels like LPG, CNG, Deisel they make
use of magnetic field forces. The magnetized coils are arranged on the guideway which repel the
strong magnet placed under train’s carriage. This helps train move over the guideway, a
technique called Electrodynamic suspension. When current passes in the coils of guideway, a
typical magnetic field is set up between the under carriage of train and guideway which pushes
and pulls the train along the guideway depending on the requirement.
The lack of friction and its aerodynamic style allows the train to move at very high speed.
(143) The force which makes maglev move is .
(A) Gravitational (B) Magnetic (C) Nuclear forces (D) Air drag
(144) The advantage of maglev train is .
(A) More friction (B) More pollution (C) Less pollution (D) Less friction
(145) The levitation of the train is due to .
(A) Mechanical force (B) Electrostatic attraction
(C) Electrostatic repulsion (D) Magnetic repulsion
Ans. :139 (B), 140 (B), 141 (B), 142 (B), 143 (B), 144 (D), 145 (D)

347

Match the columns :
(146)

Column-1 Column-2

(a) Biot-Savart’s law (p) gives direction of induced magnetic field

(b) Law of right hand thumb (q) gives intensity of induced magnetic field

(c) Fleming’s left hand rule (r) gives direction of induced current

(d) Fleming’s right hand rule (s) gives direction of force due to magnetic field.

(A) a – s, b – r, c–q d–p
(B) a – p, b – q, c–r d–s
(C) a – q, b – s, c–r d–p
(D) a – q, b – r, c–s d–p

(147)

Column-1 Column-2

P0I
(a) Magnetic field due to a straight very long wire and (p)
2r

carrying current I at a point at perpendicular
distance r from the wire

P0 I
(b) Magnetic field due to a circular coil carrying (q)
4S r

current I and radius (r), at its center.

2 P0I
(c) Magnetic field due to a circular coil of radius r and (r)
4S r

carrying current I at a point on its axis at a distance
r from it’s centre.

P0 I
(d) Magnetic field at a centre of current carrying (s) 4 2r

ring having are length r and having radius r.

(A) a – r, b – s, c – p, d–q
(B) a – r, b – p, c – s, d–q
(C) a – p, b – q, c – s, d–r
(D) a – s, b – p, c – r, d–q

348

(148) Two wires each carrying a steady current I are shown in four configurations in column I. Some
of the resulting effects are described in column II. Match the statments in column I with the
statements in column II.
Column - I Column - II
(a) (p) The magnetic fields (B) at P due to the
P
currents in the wires are in the same
direction.
(b) P (q) The magnetic fields (B) at P due to the
currents in the wires are in opposite
direction.
(c) P (r) There is no magnetic field at P.

(d) (s) The wires repel each other.
P

(A) a – p, b – r, c – q, d–s
(B) a – q, b – p, c – r, d–p
(C) a – p, b – p, c – r, d–q
(D) a – s, b – p, c – s, d–q

(149)

Column - I Column - II

(a) Moving coil galvanometer (p) having very small resistance.

(b) Ammeter (q) having medium resistance.

(c) Voltmeter (r) having very high, medium or

very small resistance.

(d) Avometer (s) having very high resistance.

(A) a – p, b – q, c – r, d–s
(B) a – p, b – q, c – s, d–r
(C) a – q, b – p, c – r, d–s
(D) a – q, b – p, c – s, d–r

Ans. : 146 (D), 147 (B), 148 (B), 149 (D)

l

349