Q.1.
Two magnets of magnetic moments M and 2M are placed in a vibration magnetometer, with the identical poles in the same direction. The time period of vibration is TIf the magnets are placed with opposite poles together and vibrate with time period T2, then ... [ CBSE-PMT 2002]
-
17%
a) T2 is infinite
-
8%
b) T2=T1
-
58%
c) T2 > T1
-
17%
d) T2 < T1
Explanation
Q.2.
A diamagnetic material in a magnetic field move... [ CBSE-PMT 2003]
-
15%
a)perpendicular to the field
-
62%
b) from stronger to the weaker parts of the field
-
23%
c)from weaker to the stronger parts of the field
-
0%
d)in none of the above directions
Q.3.
A bar magnet having a magnetic moment of 2×104 JT-1 is free to rotate in a horizontal plane. A horizontal magnetic field B=6×10-1 T exists in the space. The work done in taking the magnet slowly from a direction parallel to the field to a direction 60° from the field is .. [ CBSE-PMT 200]
-
17%
a) 12J
-
75%
b) 6J
-
0%
c)2J
-
8%
d)0.6J
Q.4.
A coil in the shape of an equilateral triangle of side 'l' is suspended between the pole pieces of a permanent magnet such that B is in the plane of the coil. If due to a current 'i' in the triangle a torque τ acts on it, the side 'l' of the triangle is [ CBSE-PMT 2005]
-
9%
a)
-
64%
b)
-
18%
c)
-
9%
d)
Explanation
Q.5.
Two identical bar magnets are fixed with their centre at a distance 'd' apart. A stationary charge Q is placed at P in between the gap of the magnets at centre O as shown in figure. The force on the charge Q is ... [ CBSE-PMT 2010]
-
15%
a) direction perpendicular to the plane of paper
-
54%
b) zero
-
23%
c) direction along OP
-
8%
d) direction along PO
Q.6.
The time period of oscillation of bar magnet suspended horizontally along the magnetic meridian is To. If this magnet is replaced by another magnet of the same size and pole strength, but with double the mass, the new time period will be [ SCRA 1994]
-
0%
a)To / 2
-
57%
b) T / √2
-
36%
c)√2 To
-
7%
d)2To
Explanation
Q.7.
At certain place a magnetic makes 30 oscillations/min. At another place where magnetic field is double., its time period will be [ MPPMT 1998]
-
33%
a) 4 sec
-
17%
b) 2 sec
-
33%
c)0.5 sec
-
17%
d)√2
Q.8.
The line on the earth's surface joining the points where the field is horizontal is called [ MNR 1985]
-
36%
a) magnetic meridian
-
27%
b) magnetic axis
-
0%
c)magnetic line
-
36%
d)magnetic equator
Q.9.
When a diamagnetic substance is brought near N or S pole of a bar magnet it is [ EAMCET 1995]
-
0%
a) Attracted
-
73%
b) Repelled
-
9%
c) Attracted by N and repelled by S pole
-
18%
d) Repelled by N pole and attracted by S pole
Q.10.
Two small magnets each of magnetic moment 10A m2 are placed in end-on position 0.1m apart from their centres. The force acting between them is [ MNR 1994]
-
20%
a) 0.6×107 N
-
30%
b) 0.06×107 N
-
30%
c)0.6 N
-
20%
d)0.06N
Explanation
Q.11.
A ferromagnetic material is heated above its curie temperature. Which of the following is correct statement?
-
9%
a) Ferro magnetic domains are perfectly arranged
-
45%
b) Ferro magnetic domains become random
-
9%
c)Ferro magnetic domains are not influenced
-
36%
d)Ferromagnetic material changes itself into diamagnetic material
Q.12.
Susceptibility is positive and small for a [ CPMT 1990]
-
55%
a) paramagnetic substance
-
18%
b) ferromagnetic substance
-
18%
c) non-magnetic substance
-
9%
d) diamagnetic substance
Q.13.
A magnetic needle lying parallel to a magnetic field requires W unit of work to turn it through 60°. The torque needed to maintain the needle in this position will be [ CET 1994]
-
45%
a)√(3) W
-
9%
b)W
-
45%
c)[√(3) W] / 2
-
0%
d)2W
Q.14.
Magnetic lines of force [ MNR 1987]
-
33%
a) can not intersect at all
-
17%
b) intersect within the magnet
-
50%
c)intersect only at south and north poles
-
0%
d)intersect at neutral point only
Q.15.
Substances, when placed in a magnetic field acquire feeble magnetization in direction opposite to that of the applied field are called [ EAMCET 1994]
-
36%
a) Diamagnetic substances
-
27%
b) Ferromagnetic substances
-
27%
c)Paramagnetic substances
-
9%
d)Ferrimagnetic substances
Q.16.
A magnet is suspended in such a way that it oscillates in the horizontal plane. It makes 20 oscillations per minute at a place where dip angle is 30° and 15 oscillations per minute at a placed where dip angle is 60°. Ratio of the total earth's magnetic field at the two places is [ MPPMT 1991]
-
10%
a) 3√3 : 8
-
50%
b) 16 : 9√3
-
10%
c) 4 : 9
-
30%
d) 2√3 : 9
Explanation
Q.17.
The magnetic induction in air at a distance d from an isolated point pole of strength m unit will be [ MPPMT 1995]
-
25%
a)m/d
-
33%
b) m / d2
-
42%
c)md
-
0%
d)md2
Q.18.
At the magnetic north pole of the earth the value of horizontal component of earth's magnetic field and angle of dip are, respectively: [ MPPMT 1994]
-
60%
a) zero, maximum
-
10%
b) maximum, minimum
-
10%
c)maximum, maximum
-
20%
d)minimum, minimum
Q.19.
A sensitive magnetic instrument can be shielded very effectively from outside fields by placing it inside a box of [ MPPMR 1995]
-
9%
a) teak wood
-
0%
b) plastic material
-
64%
c)soft iron of high permeability
-
27%
d)a metal of high conductivity
Q.20.
Magnetic material that moves from stronger to weaker parts of magnetic field is: [ EAMCET 1995]
-
9%
a) ferromagnetic
-
9%
b) paramagnetic
-
73%
c) diamagnetic
-
9%
d) anti-ferromagnetic
Q.21.
The correct value of dip angle at a place is 45°. If the circle is rotated 45° out of the meridian, then the tangent of the angle of apparent dip angle is :
-
40%
a)1
-
20%
b) 1 /√2
-
40%
c)√2
-
0%
d)1/2
Q.22.
A dip needle in a plane perpendicular to magnetic meridian will remain: [ MPPMT 1998]
-
33%
a) vertical
-
22%
b) horizontal
-
0%
c)in any direction
-
44%
d)inclined at 45° with horizontal
Q.23.
The time period of a freely suspended magnet is 4secs. if it is broken in length into two equal parts and one part is suspended in the same way, then its time period will be
-
50%
a) 4 sec
-
40%
b) 2 sec
-
10%
c)0.5 sec
-
0%
d)0.25 sec
Explanation
Q.24.
For which of the following substances, the magnetic susceptibility is independent of temperature [ CET 1994]
-
45%
a) diamagnetic only
-
36%
b) paramagnetic only
-
9%
c) ferromagnetic only
-
9%
d) diamagnetic and paramagnetic both
Q.25.
At Curie point, a ferromagnetic material becomes [ NCERT 199]
-
0%
a)non-magnetic
-
10%
b) diamagnetic
-
80%
c)paramagnetic
-
10%
d)strongly ferromagnetic
Q.26.
The magnet can be completely demagnetized by [ CET 1994]
-
36%
a) breaking the magnet into small pieces
-
18%
b) heat it slightly
-
0%
c)dropping into ice cold water
-
45%
d)a reverse field of appropriate strength
Q.27.
A permanent magnet is maid from a material which is [ CMET 1995]
-
30%
a) diamagnetic
-
20%
b) paramagnetic
-
30%
c)ferromagnetic
-
20%
d)anti ferromagnetic
Q.28.
A bar magnet is oscillating in earth's magnetic field with a period T, what happens to its period and motion if its mass is quadrupled?
-
0%
a) Motion remains simple harmonic with the new period=4T
-
60%
b) Motion remains simple harmonic with new period=T/4
-
0%
c) Motion does not remain simple harmonic and period is approx. constant
-
40%
d) Motion remains simple harmonic with the new period=2T
Q.29.
The magnetic field due to a small magnetic dipole of magnetic moment M, at distance r from the centre on the equatorial line is given by ( in MKS system) [ MPPMT 1998]
-
0%
a)
-
78%
b)
-
11%
c)
-
11%
d)
Q.30.
Each pole of a bar magnet of moment 780 units experiences a force of 1.56×10+5 when placed in a uniform field of 0.4 S.I. units. The length of the bar is [ ISM Dhandad 11994]
-
29%
a) 0.20 m
-
29%
b) 2.0 m
-
29%
c)0.002 m
-
14%
d)200 m