Q.1.
The line on the earth's surface joining the points where field is horizontal is called [ MNR 1985]
-
20%
a) magnetic meridian
-
40%
b) magnetic axis
-
0%
c)magnetic line
-
40%
d)magnetic equator
Q.2.
The period of oscillations of a magnetic needle in a magnetic field is 1.0sec. If the length of the needle is halved by cutting it the time period will be [ MPPMT 1998]
-
0%
a) 1.0 sec
-
40%
b) 0.5 sec
-
40%
c) 0.25 sec
-
20%
d) 2.0 sec
Explanation
Q.3.
At magnetic poles, the angle of dip is [ CPMT 1991]
-
25%
a)45°
-
0%
b) 30°
-
25%
c)zero
-
50%
d)90°
Q.4.
When the magnet is placed vertical, neutral points obtained on the paper are [ PMT 1985]
-
40%
a) one
-
20%
b) two
-
20%
c)three
-
20%
d)four
Q.5.
For a paramagnetic material, the dependence of the magnetic susceptibility X on the absolute temperature T is given by [ Raj.PMT 1996]
-
0%
a) X ∝ T
-
20%
b) X ∝ constant ×T
-
60%
c)X ∝ (1/T)
-
20%
d)X=constant
Q.6.
A bar magnet of magnetic moment M is cut into to parts of equal length. the magnetic moment of either part is : [ CET 1994]
-
0%
a) M
-
17%
b) 2M
-
83%
c) M/2
-
0%
d) zero
Q.7.
Metals getting magnetized by orientation of atomic magnetic moments in external magnetic field is called [ EAMCET 1991]
-
40%
a)diamagnetic
-
60%
b) paramagnetic
-
0%
c)ferromagnetic
-
0%
d)antimagnetic
Q.8.
The magnetic susceptibility for diamagnetic material is [ AMU 1995]
-
60%
a)small and negative
-
20%
b) small and positive
-
0%
c)large and positive
-
20%
d)large and negative
Q.9.
At certain place the angle of dip is 30° and the horizontal component of earth's magnetic field is 0.5 oersted. The earth's total magnetic field ( in Oersted is ) [ CPMT 1990]
-
0%
a) √3
-
0%
b) 1
-
100%
c) 1 / √3
-
0%
d) 1/2
Q.10.
The temperature at and above which a ferromagnetic material becomes paramagnetic is called [ SCRA 1994]
-
20%
a)critical temperature
-
0%
b) inversion temperature
-
60%
c)curie temperature
-
20%
d)Bebye temperature
Q.11.
Which one of the following is not maid of soft iron? [ MPPMT 1995]
-
50%
a) Electromagnet
-
0%
b) core of transformer
-
25%
c)core of dynamo
-
25%
d)Magnet of loudspeaker
Q.12.
A short magnet of moment 6.75 Am2 produces a neutral point on its axis. If the horizontal component of earth's magnetic field is 5×10-5 wb/m2, then distance of the neutral point should be [ SCRA 1994]
-
20%
a) 10 cm
-
60%
b) 20 cm
-
20%
c)30 cm
-
0%
d)40 cm
Explanation
Q.13.
Susceptibility is positive and large for [ BHU 1995]
-
40%
a) paramagnetic substance
-
0%
b) ferromagnetic substance
-
60%
c) diamagnetic substance
-
0%
d) non-magnetic substance
Q.14.
The line joining the points of zero horizontal components of earth's magnetic field is called [ MNR 1987]
-
20%
a)magnetic meridian
-
20%
b) magnetic axis
-
20%
c)magnetic line
-
40%
d)magnetic equator
Q.15.
A bar magnet of magnetic moment 104 J/T is free to rotate in a horizontal plane. the work done in rotating the magnet slowly from a direction parallel to a horizontal magnetic field of 4×10-5 T to a direction 60° from the field will be [ MPPMT 1995]
-
25%
a) 0.2 J
-
25%
b) 2.0 J
-
50%
c)4.18 J
-
0%
d)2×102 J
Q.16.
Points A and B are situated perpendicular to the axis of 2 cm long bar magnet at large distance X and 3X from the centre on opposite sides. The ratio of the magnetic field at A and B will be approximately equal to : [ CPMT 1988]
-
0%
a) 1:9
-
50%
b) 2:9
-
50%
c)27:1
-
0%
d)9:1
Q.17.
Substances which are magnetized in a magnetic field in opposite direction are called [ CPMT 1993]
-
20%
a) Diamagnetic
-
40%
b) Paramagnetic
-
20%
c) Ferromagnetic
-
20%
d) Non-magnetic
Q.18.
The time period of oscillating magnetometer is 1.5 second. The time period of oscillation of another magnet similar in size and shape, mass but having one-fourth magnetic moment than that of first magnet oscillating at the same place will be [ MPPMT 1991]
-
20%
a)0.75 sec
-
0%
b)1.5 sec
-
60%
c)3.0 sec
-
20%
d)6.0 sec
Q.19.
The work done in turning a magnet of magnetic moment 'M' by an angle of 90° from the meridian is 'n' times the corresponding done to turn it through angle of 60° where 'n' is given by [ CBSE 1995]
-
33%
a) 1/2
-
33%
b) 2
-
0%
c)1/4
-
33%
d)1
Q.20.
If a dip needle is suspended at an angle of 30° to the magnetic meridian, it makes an angle of 45° with the horizontal. The real dip is [ CPMT 1998]
-
33%
a) tan-1 (√3/2)
-
0%
b) tan-1 (√3)
-
33%
c)tan-1 √(3/2)
-
33%
d)tan-1 (2 /√3)
Q.21.
The range of permeability of paramagnetic substance is [ Raj. PMT 1996]
-
40%
a) -1 < µ < -10
-
40%
b) 1 < µ < +10
-
0%
c) 1 < µ > 10
-
20%
d) 0 < µ < 1
Q.22.
A magnet of magnetic moment M is rotated through 360° in a magnetic field H, the work done will be [ MPPMT 1994]
-
0%
a)MH
-
25%
b) 2MH
-
50%
c)2πMH
-
25%
d)zero
Q.23.
Electromagnets are made of soft iron, because soft iron has [ MNR 1988]
-
17%
a) low susceptibility and low retentivity
-
67%
b) high susceptibility and low retentivity
-
0%
c)high susceptibility and high retentivity
-
17%
d)low permeability and high retentivity
Q.24.
The angle of dip at a place on the earth gives ..[ MPPET 1994]
-
33%
a) the horizontal component of the earth's magnetic field
-
0%
b) the location of the geographic meridian
-
0%
c)the vertical component of the earth's field
-
67%
d)the direction of the earth's magnetic field
Q.25.
Magnetic lines of force due to a bar magnet do not intersect because [ PMT 1995]
-
25%
a) a point always has a single net magnetic field
-
25%
b) line have similar charges and so repel each other
-
25%
c) the lines always diverge from a single point
-
25%
d) the line need magnetic lenses to be made to intersect
Q.26.
The earth's magnetic field at a certain place has a horizontal component 0.3 Gauss and the total strength 0.5 gauss. The angle of dip is [ MPPMT 1995]
-
50%
c)tan-1 (4/3)
-
50%
a)tan-1 (3/4)
-
0%
b) sin-1 (3/4)
-
0%
d)sin-1 (3/5)
Q.27.
Point A and B are situated along the extended axis of 2cm long bar magnet at a distance x and 2x respectively from the pole nearer to the points. the ratio of the magnetic field at A and B will be [ CPMT 1986]
-
0%
a) 4:1 exactly
-
50%
b) 4:1 approximately
-
50%
c)8:1 exactly
-
0%
d)8:1 approximately
Q.28.
Using a bar magnet P, a vibration magnetometer has time period of 2seconds. When a bar Q ( identical to P in mass and size) is placed on the top of P, the time period is unchanged. Which of the following statements is true] [ PMT 1995]
-
33%
a) Q is non-magnetic material
-
67%
b) Q is a bar magnet identical to P, and its north pole is placed on top of P's north pole
-
0%
c)Q is of unmagnetized ferromagnetic material
-
0%
d)Nothing can be said about Q's properties
Q.29.
A bar magnet has a magnetic moment equal to 5×10-5 weber×metre. It is suspended in a magnetic field which has a magnetic induction (B) equal to 8π×10-4 tesla. The magnet vibrates with period of vibration equal to 15 seconds. the moment of inertia of the magnet is [ MPPMT 1993]
-
0%
a) 22.5 kg×m2
-
33%
b) 11.25 kg×m2
-
67%
c) 5.62 kg×m2
-
0%
d) 7.16×10-7 kg×m2
Explanation
Q.30.
At a place the angle of dip is 30°. If the horizontal component earth's field is H, then the total field intensity will be given by: [ MNR 1993]
-
0%
a) H / 2
-
0%
b) 2H / √3
-
100%
c)H√2
-
0%
d)H√3