# Physics MCQ Magnetic Field and Earth Magnetism ISC Class-12

Physics MCQ Magnetic Field and Earth Magnetism . These MCQ  / Objective Type Questions is based on latest reduced syllabus according 2021-22 session on bifurcated pattern. Main motto of MCQ Type Question is cracking the next upcoming exam of council. Visit official website CISCE for detail information about ISC Board Class-12 Physics.

## ISC Class-12 Physics Ch-9 MCQ Magnetic Field and Earth Magnetism

 Board ISC Class 12th (XII) Subject Physics Chapter-9 Magnetic Field and Earth Magnetism Syllabus on bifurcated syllabus (after reduction) Session 2021-22 Topic MCQ / Objective Type Question

### ISC Class-12 Physics Chapter-9 Magnetic Field and Earth Magnetism MCQ

Question 1:  The dimensional representation of magnetic flux density is :

(a) [MLT-2]
(b) [MLT-2A-1]
(c) [MLT-2A-2]
(d) [MT-2A-1]

Question 2:  A magnetic bar of M magnetic moment is placed m the field of magnetic strength B, the torque acting on it is :

(a) 𝑀⃗ .𝐵⃗
(b) –𝑀⃗ .𝐵⃗
(c) 𝑀⃗  × 𝐵⃗ .
(d) 𝐵⃗  × 𝑀⃗

Answer: (c) 𝑀⃗  × 𝐵⃗ .

Question 3: A magnetic dipole moment is a vector quantity directed from:

(a) S to N
(b) N to S
(c) E to W
(d) W to E

Answer: (a) S to N

Question 4:  Tangent law is applicable only when:

(a) two uniform and mutually perpendicular magnetic fields exist
(b) two magnetic fields exist
(c) horizontal component of earth’s magnetic field is present
(d) uniform magnetic field are used

Answer: (a) two uniform and mutually perpendicular magnetic fields exist

Question 5: S.I. unit of flux is :

(a) Ohm
(b) Weber
(c) Tesla
(d) None

Question 6: What is the angle of dip at a place where the horizontal component of earth’s magnetic field is equal to the vertical component?

(a) 0°
(b) 30°
(c) 45°
(d) 90°

Question 7: The magnetic lines of force inside a bar magnet:

(a) do not exist
(b) depends on area of cross-section of bar magnet
(c) are from N-pole to S-pole of the magnet
(d) are from S-pole to N-pole of the magnet.

Answer: (d) are from S-pole to N-pole of the magnet.

Question 8:  Ferrites may be:

(a) ant. ferromagnetic
(b) ferromagnetic
(c) ferrimagnetic
(d) None of the above

Question 9: A current carrying power line carries current from west to east. What will be direction of magnetic field 1 meter above it?

(a) N to S
(b) S to N
(c) E to W
(d) W to E

Answer: (a) N to S

Question 10: The dimensional representation of l/MB is similar to that of:

(a) frequency
(b) time
(c) distance
(d) speed

Question 11: The earth behaves as a magnet with magnetic field pointing approximately from the geographic

(a) North to South
(b) South to North
(c) East to West
(d) West to East

Answer: (a) North to South

Question 12: Which of the following is responsible for the earth’s magnetic field?

(а) Convective currents in earth’s core
(б) Diversive current in earth’s core.
(c) Rotational motion of earth.
(d) Translational motion of earth.

Answer: (а) Convective currents in earth’s core

Question 13: Which of the following independent quantities is not used to specify the earth’s magnetic field?

(a) Magnetic declination (θ).
(b) Magnetic dip (δ).
(c) Horizontal component of earth’s field (BH).

(d) Vertical component of earth’s field (BV).

Answer: (d) Vertical component of earth’s field (BV).

Question 14: The vertical component of earth’s magnetic field . at a place is √3 times the horizontal component the value of angle of dip at this place is

(a) 30°
(b) 45°
(c) 60°
(d) 90°

Question 15:  At a given place on earth’s surface the horizontal component of earth’s magnetic field is 2 × 103-5 T and resultant magnetic field is 4 × 103-5 T. The angle of dip at this place is

(a) 30°
(b) 60°
(c) 90°
(d) 45°

Question 16:  The net magnetic flux through any closed surface, kept in a magnetic field is

(a) zero
(b) μο/4π
(c) 4πμο
(d) 4μο/π

Question 17:  For which of the following is magnetic susceptibility negative?

(a) Paramagnetic and Ferromagnetic materials

(b) Paramagnetic Materials only

(c) Ferromagnetic Materials only

(d) Diamagnetic Materials

Answer: (d) Diamagnetic Materials

Question 18:  Which of the following is the unit of magnetic flux density?

(a) Weber/meter2

(b) Tesla

(c) Newton/ampere-metre

(d) All of the above

Question 19:  What is the magnetic field in the empty space enclosed by the toroidal solenoid of radius ‘R’?

(a) Infinity
(b) µ04π.2π𝑙𝑅
(c) µ04π.(π𝑙𝑅)
(d) zero

Question 20:  On quadrupling the moment of inertia of a magnet, its frequency of oscillation will become:

(a) half
(b) double
(c) four times
(d) one-fourth

Question 21:  The magnetic field strength due to a short bar magnet directed along its axial line at a distance r is B. What is its value at the same distance along the equatorial line?

(a) B
(b) 2B
(c) B/2
(d) B/4

Question 22:  The neutral point in the magnetic field of a horizontally placed bar magnet is a point where the magnetic field due to that bar magnet is:

(a) zero
(b) more than that of earth
(c) less than that of earth
(d) equal to that of earth

Answer: (d) equal to that of earth

Question 23:  A current carrying power line carries current from west to east. What will be direction of magnetic field 1 meter above it?

(a) N to S
(b) S to N
(c) E to W
(d) W to E

Answer: (a) N to S

Question 24:  A wire of length I has a magnetic moment M. It is then bent into a semi-circular arc. The neyv magnetic moment is :

(a) M
(b) M.l.
(c) 2M/π
(d) M/π

Question 25:  The magnetic field strength due to a short bar magnet directed along its axial line at a distance r is B. What is its value at the same distance along the equatorial line?

(a) B
(b) 2B
(c) B/2
(d) B/4

Question 26: In a moving coil galvanometer, we use a radial magnetic field so that the galvanometer scale is :

(a) exponential
(b) linear
(c) algebraic
(d) logarithmic

Question 27: The force between two parallel wire 2 × 10-7 Nm-1, placed 1 m apart to each other in vacuum. The electric current flowing through the wires is:

(a) 1 A
(b) zero
(c) 5 × 106 A
(d) 2 × 10-7 A

Answer: (a) 1 A

Question 28:  The strength of the earth’s magnetic field is

(a) constant everywhere.
(b) zero everywhere.
(c) having very high value.
(d) vary from place to place on the earths surface.

Answer: (d) vary from place to place on the earths surface.

Question 29:  Let the magnetic field on earth be modelled by that of a point magnetic dipole at the centre of earth. The angle of dip at a point on the geographical equator is

(a) always zero
(b) positive, negative or zero
(c) unbounded
(d) always negative

Answer: (b) positive, negative or zero

Question 30:  The primary origin of magnetism lies in

(a) atomic current and intrinsic spin of electrons.
(b) polar and non polar nature of molecules.
(c) pauli exclusion principle.
(d) electronegative nature of materials.

Answer: (a) atomic current and intrinsic spin of electrons.

Question 31:   Magnetic moment for solenoid and corresponding bar magnet is

(a) equal for both
(b) more for solenoid
(c) more for bar magnet
(d) none of these

Answer: (a) equal for both

Question 32:  The magnetism of a magnet is due to

(a) earth

(b) cosmic rays

(c) due to pressure of big magnet inside the earth

(d) spin motion of electrons

Answer: (d) spin motion of electrons

Question 33:  The magnetic field at a point x on the axis of a mall bar magnet is equal to the field at a point y on the equator of the same magnet. The ratio of the distances of x and y from the centre of the magnet is

(a) 2-1/3

(b) 21/3

(c) 23

(d) 2-3

Question 34:  Which of the following materials is the most suitable for making a permanent magnet?

(a) Soft Iron

(b) Nickel

(c) Copper

(d) teel

Question 35: The magnetic field of earth is due to:

(a) induction effect of the sun
(b) the presence of a large magnet at the centre of the earth
(c) interaction of cosmic rays with the current of earth
(d) motion and distribution of some material in an outside the earth

Answer: (d) motion and distribution of some material in an outside the earth

Question 36: The radius of curvature of the path of charged particle in a uniform magnetic file is directly proportional to the

(a) charge on fie particle
(b) Momentum of particle
(c) energy of particle
(d) Strength of field

Answer: (b) Momentum of particle

Question 37: The magnetic lines of force inside a bar magnet:

(a) do not exist
(b) depends on area of cross-section of bar magnet
(c) are from N-pole to S-pole of the magnet
(d) are from S-pole to N-pole of the magnet.

Answer: (d) are from S-pole to N-pole of the magnet.

Question 38: In a bar magnet, magnetic lines of force z :

(a) are produced only at north pole like rays of light from a bulb
(b) starts from north pole and ends at the south pole
(c) emerge in circular paths from the middle of the bar
(d) run continuously through the bar and outside

Answer: (b) starts from north pole and ends at the south pole

Question 39: A sensitive magnetic field instrument can be effectively shielded from the external magnetic field by placing it inside which of the following materials?

(a) Plastic Material

(b) Teak Wood

(c) Soft Iron of high permeability

(d) A metal of high conductivity

Answer: (c) Soft Iron of high permeability

Question 40: A long magnet is cut into two parts such that the ratio of their lengths is 2:1. What is the ratio pole strength of both the section?

(a) 1:2

(b) 2:1

(c) 4:1

(d) Equal

Question 41: The Mariner’s compass is provided with Gimbals arrangement so as to :
(a) keep the needle always horizontal
(b) give a direct reading of declination
(c) give the direct value of dip
(d) all of the above

Answer: (c) give the direct value of dip

Question 42: Which of the following statements is true about magnetic field intensity?

(a) Magnetic field intensity is the number of lines of force crossing per unit volume.

(b) Magnetic field intensity is the number of lines of force crossing per unit area.

(c) Magnetic field intensity is the magnetic induction force acting on a unit magnetic pole.

(d) Magnetic field intensity is the magnetic moment per unit volume.

Answer: (c) Magnetic field intensity is the magnetic induction force acting on a unit magnetic pole

Question 43: Which of the following is not showing the essential difference between electrostatic shielding by a conducting shell and magnetostatic shielding?

(a) Electrostatic field lines can end on charges and conductors have free charges.
(b) Magnetic field lines can end but conductors cannot end them.
(c) Lines of magentic field cannot end on any material and perfect shielding is not possible.
(d) Shells of high permeability materials can be used to divert lines of magnetic field from the interior region.

Answer: (b) Magnetic field lines can end but conductors cannot end them.

Question 44:  What happens to the magnetic needle kept in a non-uniform magnetic field?

(a) It experiences force but not torque

(b) It experiences torque but not force

(c) It experiences both force and torque

(d) It neither experiences force nor torque

Answer: (a) It experiences force but not torque

Question 45: What is the torque acting on the bar magnet of moment M which is placed in a uniform field H making an angle of 300 with the field?

(a) MH

(b) MH/2

(c) MH/3

(d) MH/4

Question 46:  What is the work done by the magnet of moment M if it is rotated through 3600 in magnetic field H?

(a) 2MH

(b) MH

(c) 2πMH

(d) Zero

Question 47:  Magnetic lines of force of a bar magnet do not intersect because

(a) The lines have similar charges hence they repel each other

(b) The lines always diverge from a single point

(c) A point always has a single net magnetic field

(d) The lines need magnetic lenses to intersect

Answer: (c) A point always has a single net magnetic field

-: End of Ch-9 MCQ Magnetic Field and Earth Magnetism for ISC Class-12 :-

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