Q.1
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]
  • a) 1.0 sec
  • b) 0.5 sec
  • c) 0.25 sec
  • d) 2.0 sec
Q.2
At magnetic poles, the angle of dip is [ CPMT 1991]
  • a)45°
  • b) 30°
  • c)zero
  • d)90°
Q.3
When the magnet is placed vertical, neutral points obtained on the paper are [ PMT 1985]
  • a) one
  • b) two
  • c)three
  • d)four
Q.4
For a paramagnetic material, the dependence of the magnetic susceptibility X on the absolute temperature T is given by [ Raj.PMT 1996]
  • a) X ∝ T
  • b) X ∝ constant ×T
  • c)X ∝ (1/T)
  • d)X=constant
Q.5
A bar magnet of magnetic moment M is cut into to parts of equal length. the magnetic moment of either part is : [ CET 1994]
  • a) M
  • b) 2M
  • c) M/2
  • d) zero
Q.6
Metals getting magnetized by orientation of atomic magnetic moments in external magnetic field is called [ EAMCET 1991]
  • a)diamagnetic
  • b) paramagnetic
  • c)ferromagnetic
  • d)antimagnetic
Q.7
The magnetic susceptibility for diamagnetic material is [ AMU 1995]
  • a)small and negative
  • b) small and positive
  • c)large and positive
  • d)large and negative
Q.8
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]
  • a) √3
  • b) 1
  • c) 1 / √3
  • d) 1/2
Q.9
The temperature at and above which a ferromagnetic material becomes paramagnetic is called [ SCRA 1994]
  • a)critical temperature
  • b) inversion temperature
  • c)curie temperature
  • d)Bebye temperature
Q.10
Which one of the following is not maid of soft iron? [ MPPMT 1995]
  • a) Electromagnet
  • b) core of transformer
  • c)core of dynamo
  • d)Magnet of loudspeaker
Q.11
Susceptibility is positive and large for [ BHU 1995]
  • a) paramagnetic substance
  • b) ferromagnetic substance
  • c) diamagnetic substance
  • d) non-magnetic substance
Q.12
The line joining the points of zero horizontal components of earth's magnetic field is called [ MNR 1987]
  • a)magnetic meridian
  • b) magnetic axis
  • c)magnetic line
  • d)magnetic equator
Q.13
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]
  • a) 1:9
  • b) 2:9
  • c)27:1
  • d)9:1
Q.14
Substances which are magnetized in a magnetic field in opposite direction are called [ CPMT 1993]
  • a) Diamagnetic
  • b) Paramagnetic
  • c) Ferromagnetic
  • d) Non-magnetic
Q.15
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]
  • a)0.75 sec
  • b)1.5 sec
  • c)3.0 sec
  • d)6.0 sec
Q.16
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]
  • a) 1/2
  • b) 2
  • c)1/4
  • d)1
Q.17
The range of permeability of paramagnetic substance is [ Raj. PMT 1996]
  • a) -1 < µ < -10
  • b) 1 < µ < +10
  • c) 1 < µ > 10
  • d) 0 < µ < 1
Q.18
A magnet of magnetic moment M is rotated through 360° in a magnetic field H, the work done will be [ MPPMT 1994]
  • a)MH
  • b) 2MH
  • c)2πMH
  • d)zero
Q.19
Electromagnets are made of soft iron, because soft iron has [ MNR 1988]
  • a) low susceptibility and low retentivity
  • b) high susceptibility and low retentivity
  • c)high susceptibility and high retentivity
  • d)low permeability and high retentivity
Q.20
The angle of dip at a place on the earth gives ..[ MPPET 1994]
  • a) the horizontal component of the earth's magnetic field
  • b) the location of the geographic meridian
  • c)the vertical component of the earth's field
  • d)the direction of the earth's magnetic field
Q.21
Magnetic lines of force due to a bar magnet do not intersect because [ PMT 1995]
  • a) a point always has a single net magnetic field
  • b) line have similar charges and so repel each other
  • c) the lines always diverge from a single point
  • d) the line need magnetic lenses to be made to intersect
Q.22
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]
  • c)tan⁻¹ (4/3)
  • d)sin⁻¹ (3/5)
  • a)tan⁻¹ (3/4)
  • b) sin⁻¹ (3/4)
Q.23
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]
  • a) 4:1 exactly
  • b) 4:1 approximately
  • c)8:1 exactly
  • d)8:1 approximately
Q.24
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]
  • a) Q is non-magnetic material
  • b) Q is a bar magnet identical to P, and its north pole is placed on top of P's north pole
  • c)Q is of unmagnetized ferromagnetic material
  • d)Nothing can be said about Q's properties
Q.25
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]
  • a) H / 2
  • b) 2H / √3
  • c)H√2
  • d)H√3
Q.26
Vibration magnetometer work on the principle of [ MPPMT 199]
  • a) Torque acting on the bar magnet
  • b)Force acting on the bar magnet
  • c)Both the force and the torque acting on the bar magnet
  • d)None of the above
Q.27
A magnetic needle suspended by a silk-thread is vibrating in the earth's magnetic field. If the temperature of the needle is increased by 500°C, then [ MNR 1995]
  • a) the time periode decreases
  • b) the time period remains unchanged
  • c)the time period increases
  • d)the needle stops vibrating
Q.28
A bar magnet is placed North-south with its North pole due North. The point of zero magnetic field will be in which direction from the centre of the magnet? [ PMT 1995]
  • a) North and South
  • b) East and West
  • c) North-East and South-West
  • d) North-West and South-East
Q.29
A bar magnet of magnetic moment M is kept in uniform magnetic field of strength b making angle θ with its direction. The torque acting on it is [ MPPMT 1998]
  • a)MB
  • b) MBcosθ
  • c)MB( 1- cosθ)
  • d)MBsinθ
Q.30
If a piece of metal was through to be magnet, which one of the following observations would offer conclusive evidence? [ CET 1994]
  • a) it attracts a known magnet
  • b) it repels a known magnet
  • c)non of the above
  • d)it attracts a steel screw driver
0 h : 0 m : 1 s