CBSE Class 12 Physics Magnetism and Matter MCQs Set C

Question. The magnetic susceptibility is negative for
(a) ferromagnetic material only
(b) paramagnetic and ferromagnetic materials
(c) diamagnetic material only
(d) paramagnetic material only

Answer : C

Question. There are four light-weight-rod samples A, B, C, D separately suspended by threads. A bar magnet is slowly brought near each sample and the following observations are noted
(i) A is feebly repelled
(ii) B is feebly attracted
(iii) C is strongly attracted
(iv) D remains unaffected
Which one of the following is true?
(a) B is of a paramagnetic material
(b) C is of a diamagnetic material
(c) D is of a ferromagnetic material
(d) A is of a non-magnetic material

Answer : A

Question. Liquid oxygen remains suspended between two pole forces of a magnet because it is :
(a) diamagnetic
(b) paramagnetic
(c) ferromagnetic
(d) antiferromagnetic

Answer : B

Question. The magnetic susceptibility of an ideal diamagnetic substance is
(a) –1
(b) 0
(c) +1
(d) ¥

Answer : A

Question. A magnet 10 cm long and having a pole strength 2 amp m is deflected through 30° from the magnetic meridian. The horizontal component of earth’s induction is 0.32´10^-4 tesla then the value of deflecting couple is: 
(a) 32 ´10^-7Nm
(b) 16 ´10^-7Nm
(c) 64 ´10^-7Nm
(d) 48 ´10^-7Nm

Answer : A

Question. Which one of the following statement is not correct about the magnetic field ?
(a) Inside the magnet the lines go from north pole to south pole of the magnet
(b) Tangents to the magnetic lines give the direction of the magnetic field
(c) The magnetic lines form a closed loop
(d) Magnetic lines of force do not cut each other

Answer : A

Question. A bar magnet of magnetic moment M is cut into two parts of equal length. The magnetic moment of each part will be
(a) M
(b) 2M
(c) zero
(d) 0.5M

Answer : D

Question. The work done in turning a magnet of magnetic moment M by an angle of 90° from the meridian, is n times the corresponding work done to turn it through an angle of 60°. The value of n is given by
(a) 1/2
(b) 1/4
(c) 2
(d) 1

Answer : C

Question. If relative permeability of iron is 2000. Its absolute permeability in S.I. units is
(a) 8π × 10^–4
(b) 8π × 10^–3
(c) 800/π
(d) 8π × 109/π

Answer : A

Question. If the magnetic dipole moment of an atom of diamagnetic material, paramagnetic material and ferromagnetic material are denoted by md, mp and mf respectively, then
(a) md = 0 and mp ≠ 0
(b) md ≠ 0 and mp = 0
(c) mp = 0 and mf ≠ 0
(d) md ≠ 0 and mf ≠ 0.

Answer : A

Question. According to Curie’s law, the magnetic susceptibility of a substance at an absolute temperature T is proportional to
(a) T²
(b) I / T
(c) T
(d) I / T²

Answer : B

Question. The magnetic materials having negative magnetic susceptibility are
(a) non-magnetic
(b) para magnetic
(c) dia magnetic
(d) ferro magnetic

Answer : C

Question. Curie temperature is the temperature above which
(a) a ferromagnetic material becomes paramagnetic
(b) a paramagnetic material becomes diamagnetic
(c) a ferromagnetic material becomes diamagnetic
(d) a paramagnetic material becomes ferromagnetic

Answer : A

Question. For protecting a sensitive equipment from the external magnetic field, it should be
(a) surrounded with fine copper sheet
(b) placed inside an iron can
(c) wrapped with insulation around it when passing current through it
(d) placed inside an aluminium can

Answer : B

Question. Electromagnets are made of soft iron because soft iron has
(a) low retentivity and high coercive force
(b) high retentivity and high coercive force
(c) low retentivity and low coercive force
(d) high retentivity and low coercive force

Answer : C

Question. The materials suitable for making electromagnets should have
(a) high retentivity and low coercivity
(b) low retentivity and low coercivity
(c) high retentivity and high coercivity
(d) low retentivity and high coercivity

Answer : B

Question. The magnetic moment of a diamagnetic atom is
(a) equal to zero
(b) much greater than one
(c) unity
(d) between zero and one

Answer : A

Question. A diamagnetic material in a magnetic field moves
(a) from stronger to the weaker parts of the field
(b) from weaker to the stronger parts of the field
(c) perpendicular to the field
(d) in none of the above directions

Answer : A

Question. According to Curie’s law, the magnetic susceptibility of a substance at an absolute temperature T is proportional to
(a) 1/T
(b) T
(c) 1/T²
(d) T²

Answer : A

Question. A bar magnet 8 cms long is placed in the magnetic merdian with the N-pole pointing towards geographical north. Two netural points separated by a distance of 6 cms are obtained on the equatorial axis of the magnet. If horizontal component of earth’s field = 3.2 × 10^–5 T, then pole strength of magnet is
(a) 5 ab-amp × c
(b) 10 ab-amp × cm
(c) 2.5 ab-amp × cm
(d) 20 ab-amp × cm

Answer : A

Question. A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It
(a) will become rigid showing no movement
(b) will stay in any position
(c) will stay in north-south direction only
(d) will stay in east-west direction only

Answer : B

Question. Tangent galvanometer is used to measure
(a) potential difference
(b) current
(c) resistance
(d) charge.

Answer : B

Question. Work done in turning a magnet of magnetic moment M by an angle of 90º from the mgnetic meridian is n times the corresponding work done to turn through an angle of 60º, where n is
(a) 1/2
(b) 2
(c) 1/4
(d) 1

Answer : B

Question. If a diamagnetic substance is brought near the north or the south pole of a bar magnet, it is
(a) repelled by the north pole and attracted by the south pole
(b) attracted by the north pole and repelled by the south pole
(c) attracted by both the poles
(d) repelled by both the poles

Answer : D

Question. If q1 and q2 be the apparent angles of dip observed in two vertical planes at right angles to each other, then the true angle of dip q is given by
(a) tan²Θ = tan²Θ₁ + tan²Θ₂
(b) cot²Θ = cot²Θ₁ – cot²Θ₂
(c) tan²Θ = tan²Θ₁ – tan²Θ₂
(d) cot²Θ = cot²Θ₁ + cot²Θ₂ 

Answer : D

Question. Two magnets are held together in a vibration magnetometer and are allowed to oscillate in the earth’s magnetic field with like poles together. 12 oscillations per minute are made but for unlike poles together only 4 oscillations per minute are executed. The ratio of their magnetic moments is
(a) 3 : 1
(b) 1 : 3
(c) 3 : 5
(d) 5 : 4

Answer : D