Q.1
The magnetic moment of a single atom of a diamagnetic substance is
  • a) zero
  • b) less than zero
  • c)slightly more than zero
  • d)much more than zero
Q.2
Above Curie temperature a paramagnetic substance becomes
  • a) paramagnetic
  • b) diamagnetic
  • c) ferromagnetic
  • d) super conductor
Q.3
Three identical bar magnets each of magnetic moment M, are placed in the form of an equilateral triangle with north pole of one touching the south pole of other as shown in figure. The net magnetic moment of he system is
ch-17_que_no-161_img_no1.png
  • a)zero
  • b) 3M
  • ac)3M/2
  • d)M√3
Q.4
A dip needle vibrates in the vertical plane perpendicular to the magnetic meridian. the time period of vibration is found to be 2 seconds. The same needle is then allowed to vibrate in the horizontal plane and the time period is again found to be 2 second. Then the angle of dip is
  • a) 0°
  • b) 30°
  • c)45°
  • d)90°
Q.5
The magnetic induction in air at a distance d from the centre of bar magnet of length 2l along the axis is ( of pole strength m unit):
  • a) m/d
  • b) 2md/(d² - l²)²
  • c)m(d² - l²)
  • d)m/(d² - l²)
Q.6
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.7
The time of vibration of dip needle vibrating in the vertical plane in the magnetic meridian in 3 seconds. When the same magnetic needle is made to vibrate in the horizontal plane , the time of vibration is 3√2 seconds. then the angle of dip is
  • a)30°
  • b) 45°
  • c)60°
  • d)90°
Q.8
Magnetic lines of forces .. [ MPPMT 1994]
  • a) always intersect
  • b) are always closed
  • c)tend to crowed far away from the poles of magnet
  • d)do not pass through vacuum
Q.9
The plane of the dip circle is set in the geographical meridian and the apparent dip is θIt is then set in a vertical plane perpendicular to the geographical meridian, the apparent dip becomes θthe angle of declination 'a' at that place is given by
  • a) tanα=√[tanθ1tanθ2]
  • b) tanα=√[(tanθ1)2 + (tanθ2)2]
  • c)tanα=tanθ1 /tanθ2
  • d)tanα=tanθ2 /tanθ1
Q.10
When a magnetic field is applied in a direction perpendicular to the direction of cathode rays, then their
  • a) energy decreases
  • b) energy increases
  • c) momentum increases
  • d) momentum and energy remains unchanged
Q.11
The coil of a tangent galvanometer is put in magnetic meridian
  • a)to avoid the magnetic effect of the erath field
  • b) to produce intense magnetic field at the centre of coil
  • c)to produce a field at right angle to earth's field
  • d)to avoid error due to parallax
Q.12
A short bar magnet placed with its axis at 30° with a uniform external magnetic field of 0.16 Tesla experiences a torque of magnitude 0.032 Joule. the magnetic moment of the bar magnet will be
  • a) 0.23 joule/tesla
  • b) 0.40 joule/tesla
  • c)0.80 joule/tesla
  • d)zero
Q.13
Magnetic line of force due to bar magnet do not intersect because
  • a) a point always has a single net magnetic field.
  • b) the lines have similar charges and so repel each other
  • c) the lines always diverge from a single point
  • d) the lines need magnetic lenses to be made to intersect
Q.14
A magnet is suspended horizontally in the earth's magnetic flux. When it is displaced and then released, it oscillates in a horizontal plane with a period T. If a piece of wood of the same moment of inertia ( about the axis of rotation) as the magnet is attached to the magnet what would be the new period of oscillation of the system become?
  • a)T/3
  • b) T/2
  • c)T/√2
  • d)T√2
Q.15
The earth's magnetic field at a certain place has horizontal component 0.3 gauss and the total strength 0.5 gauss. The angle of dip is [ MPPMT 1995]
  • a) tan⁻¹(3/4)
  • b) sin⁻¹(3/4)
  • c)tan⁻¹(4/3)
  • d)sin⁻¹(3/5)
Q.16
Ferromagnetics own their properties due to
  • a) filled inner subshells
  • b) vacant inner subshells
  • c)partially filled inner subshells
  • d)all the sub-shell equally filled
Q.17
Points A and B are situated along the extended axis of 2 cm long bar magnet at distance x and 2x cm respectively from the pole nearer to the points. The ratio of the magnetic fields 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.18
The period of oscillations of magnetic needle in a magnetic field is 1.0 sec. If the length of the needle is halved by cutting it, the time period will be
  • a) 1.0 sec
  • b) 0.5 sec
  • c)0.25 sec
  • d)2.0 sec
Q.19
The period of oscillation of a bar magnet in a vibration magnetometer is 2 sec. the period of oscillation of a bar magnet whose magnetic moment is 4 times that of 1st magnet is
  • a) 4 sec
  • b) 1 sec
  • c)2 sec
  • d)0.5 sec
Q.20
A bar magnet of length 10cm and having the pole strength equal to 10- weber is kept in the magnetic field having magnetic induction (B) equal to 4π × 10-3 tesla. It makes an angle of 30° with the direction of magnetic induction (B). The value of the torque acting on the magnet is
  • a) 2π × 10-7 newton × metre
  • b)2π × 10-5 newton × metre
  • c)0.5 newton × metre
  • d)0.5 × 102 newton × metre
Q.21
Due to earth's magnetic field, charged cosmic ray particles [ CBSE 1997]
  • a)requires greater kinetic energy to reach equator than the pole
  • b) require less kinetic energy to reach the equator than the pole
  • c)can never reach the pole
  • d)can never reach the equator
Q.22
The needle of dip circle when placed at a geometric pole stays long
  • a) south north direction only
  • b) east west direction only
  • c)vertical direction
  • d)none of above
Q.23
The magnetic susceptibility for diamagnetic material is
  • a) small and negative
  • b) small and positive
  • c)large and positive
  • d)large and negative
Q.24
The correct value of dip angle at a place is 45°. If the dip circle is rotated 45° out of the meridian, then the tangent of the angle of apparent dip is
  • a) 1
  • b) 1/√2
  • c) √2
  • d) 1/2
Q.25
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
  • a)√3
  • b) 1
  • c)1 / √3
  • d)1/2
Q.26
Two small magnets each of magnetic moment 10 Am2 are placed in end on position 0.1m apart from their centres. The force acting between them is
  • a) 0.6 × 107 N
  • b) 0.006 × 107 N
  • c)0.6 N
  • d)0.06 N
Q.27
At a certain place, horizontal component is √3 times the vertical component. the angle of dip at this place is
  • a) 0
  • b) π/3
  • c)π/6
  • d)none of the above
Q.28
A steel wire of length l has a magnetic moment M. It is then bent into a semicircular arc. the new magnetic moment is
  • a) M
  • b) 2M/π
  • c) M/l
  • d) M × l
Q.29
Two identical magnetic dipoles of magnetic moment 1.0 Am2 each, placed at sepration of 2m with their axis perpendicular to each other. The resultant magnetic field at a point midway between the dipole is
  • a)5 × 10⁻⁷ T
  • b) √5 × 10⁻⁷ T
  • c)10-7 T
  • d)2 × 10⁻⁷ T
Q.30
The force between two short bar magnets with magnetic moments M1 and M2 whose centres are r metre apart is 8N, when their axes are in same line. If the sepration is increased to 2r, the force between them is reduced to
  • a) 4N
  • b) 2N
  • c)1N
  • d)0.5N
0 h : 0 m : 1 s