Magnetism and Matter

Magnetism and Matter Class 12 Physics MCQs

1. 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

2. 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.

3. 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.

4. 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 (B_H).
(d) Vertical component of earth’s field (B_V).

5. 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

6. The angle of dip at a certain place where the horizontal and vertical components of the earth’s magnetic field are equal is
(a) 30°
(b) 75°
(c) 60°
(d) 45°

7. 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°

8. At a given place on earth’s surface the horizontal component of earth’s magnetic field is 2 × 10^3-5 T and resultant magnetic field is 4 × 10^3-5 T. The angle of dip at this place is
(a) 30°
(b) 60°
(c) 90°
(d) 45°

9. Which of the following property shows the property of ferromagnetic substances?
(a) The ferromagnetic property depends on tem-perature. ‘
(b) The ferromagnetic property does not depend on temperature.
(c) At high enough temperature ferromagnet becomes a diamagnet.
(d) At low temperature ferromagnet becomes a paramagnet.

10. 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.

11. 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

12. Which of the following is correct about magnetic monopole?
(a) Magnetic monopole exist.
(b) Magnetic monopole does not exist.
(c) Magnetic monopole have constant value of monopole momentum.
(d) The monopole momentum increase due to increase at its distance from the field.

13. Two identical bar magnets are fixed with their centres at a distance d apart. A stationary charge Q is placed at P in between the gap of the two magnets at a distance D from the centre O as shown in the figure. The force on the charge Q is

(a) zero
(b) directed along OP
(c) directed along PO
(d) directed perpendicular to the plane of paper

14. A current carrying loop is placed in a uniform magnetic field in four different orientations as shown in figure. Arrange them in the decreasing order of potential energy.

(a) 4, 2, 3,1
(b) 1, 4, 2, 3
(c) 4, 3, 2,1
(d) 1, 2, 3, 4

15. 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.

16. The net magnetic flux through any closed surface, kept in a magnetic field is
(a) zero
(b) \(\frac{\mu_{0}}{4 \pi}\)
(c) 4πμ₀
(d) \(\frac{4 \mu_{0}}{\pi}\)

17. Point out the correct direction of magnetic field in the given figures.

Question 18.
S.I. unit of flux is :
(a) Ohm
(b) Weber
(c) Tesla
(d) None

Question 19.
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 20.
Which of the following has a low value in ferrites?
(a) Conductivity
(b) Permeability
(c) Magnetic susceptibility
(d) All the above

Question 21.
The dimensional representation of magnetic flux density is :
(a) [MLT^-2]
(b) [MLT^-2A^-1]
(c) [MLT^-2A^-2]
(d) [MT^-2A^-1]

Question 22.
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

Question 23.
Ferrites may be:
(a) ant. ferromagnetic
(b) ferromagnetic
(c) ferrimagnetic
(d) None of the above

Question 24.
A magnetic bar of M magnetic moment is placed m the field of magnetic strength B, the torque acting on it is :
(a) \(\vec{M} \).\(\vec{B} \)
(b) –\(\vec{M} \).\(\vec{B} \)
(c) \(\vec{M} \) × \(\vec{B} \).
(d) \(\vec{B} \) × \(\vec{M} \)

Question 25.
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.

Question 26.
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

Question 27.
What is the magnetic field in the empty space enclosed by the toroidal solenoid of radius ‘R’? ,
(a) Infinity
(b) \(\frac{µ_0}{4π}\).\(\frac{2πl}{R}\)
(c) \(\frac{µ_0}{4π}\).(\(\frac{πl}{R}\))
(d) zero

Question 28.
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

Question 29.
The dimensional representation of \(\sqrt{l/MB}\) is similar to that of:
(a) frequency
(b) time
(c) distance
(d) speed

Question 30.
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 31.
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) \(\frac{B}{2}\)
(d) \(\frac{B}{4}\)

Question 32.
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

Question 33.
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 34.
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

Question 35.
The force acting per unit length of a semi circular wire of radius R carrying a current I is:
(a) \(\frac{µ_0l^2}{4R}\)
(b) \(\frac{µ_0l^2}{2R}\)
(c) \(\frac{µ_0l^2}{R}\)
(d) \(\frac{2µ_0l^2}{R}\)

Question 36.
Which of the following has higher magnetic susceptibility?
(a) diamagnetic
(b) paramagnetic
(c) ferromagnetic
(d) None of these

Question 37.
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

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

Question 39.
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

Question 40.
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) \(\frac{2M}{π}\)
(d) \(\frac{M}{π}\)

Question 41.
The relation between geometric length (L) and magnetic length (L_m) is:
(a) L_m = \(\frac{5}{6}\) L_g
(b) L_m = \(\frac{6}{5}\) L_g
(c) (a) L_m = L_g
(d) L_m = 2RY;UL L_g

Question 42.
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

Question 43.
The magnetic field at the centre of a current carrying circular loop is B. If the radius of the loop is doubled keeping the current unchanged, the magnetic field at the centre of loop will become:
(a) \(\frac{B}{2}\)
(b) \(\frac{B}{4}\)
(c) 2B
(d) 4B