CBSE Class 12 Physics Magnetism and Matter Boards Questions Worksheet

Important Questions for NCERT Class 12 Physics Magnetism And Matter 

Question. A frog can be levitated in a magnetic field produced by a current in a vertical solenoid placed below the frog. This is possible because the body of the frog behaves as : 

(a) paramagnetic
(b) diamagnetic
(c) ferromagnetic  
(d) antiferromagnetic

Answer :  C

Question. Domain formation is the necessary feature of : 
(a) ferromagnetism
(b) diamagnetism
(c) paramagnetism
(d) all of these

Answer :  A

Question. The best material for the core of a transformer is
(a) mild steel
(b) stainless steel
(c) soft iron
(d) hard steel 

Answer :  C

Question. What happens, when a magnetic substance is heated ? 
(a) It loses its magnetism
(b) It becomes a strong magnet
(c) Does not effect the magnetism
(d) Either (b) and (c)

Answer :  A

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 makes 40 oscillation per minute at a place having magnetic intensity of 0.1 × 10^–5 tesla. At another place it takes 2.5 sec to complete one oscillation. The value of earth's horizontal field at that place is 
(a) 0.76 × 10^–6 tesla
(b) 0.18 × 10^–6 tesla
(c) 0.09 × 10^–6 tesla
(d) 0.36 × 10^–6 tesla

Answer :  D

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. Magnetic lines of force due to a 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 force
(d) the lines need magnetic lenses to be made to interest

Answer :  A

Question. A 250-turn rectangular coil of length 2.1 cm and width 1.25 cm carries a current of 85 mA and subjected to a magnetic field of strength 0.85 T. Work done for rotating the coil by 180° against the torque is
(a) 4.55 mJ
(b) 2.3 mJ
(c) 1.15 mJ
(d) 9.1 mJ

Answer :  D

Question. A bar magnet is hung by a thin cotton thread in a uniform horizontal magnetic field and is in equilibrium state. The energy required to rotate it by 60° is W. Now the torque required to keep the magnet in this new position is
(a) W/√3
(b) √3W
(c) √3W /2
(d) 2W /√3

Answer :  B

Question. Which one of the following are used to express intensity of magnetic field in vacuum ? 
(a) oersted
(b) tesla
(c) gauss
(d) none of these

Answer :  A

Question. A bar magnet of magnetic moment M is placed at right angles to a magnetic induction B. If a force F is experienced by each pole of the magnet, the length of the magnet will be
(a) MB/F
(b) BF/M
(c) MF/B
(d) F/MB

Answer :  A

Question. A magnetic needle suspended parallel to a magnetic field requires 3 J of work to turn it through 60°.
The torque needed to maintain the needle in this position will be
(a) 2√3J
(b) 3 J
(c) √3 J
(d) 3 /2 J

Answer :  B

Question. The north pole of a magnet is brought near a metallic ring. Then the direction of the induced current in the ring will be: 
(a) Towards north
(b) Towards south
(c) Anticlockwise
(d) Clockwise

Answer :  C

Question Angle of dip is 90° at:
(a) Equator
(b) Middle point
(c) Poles
(d) None of these

Answer :  C

Question. A short bar magnet of magnetic moment 0.4 J T^–1 is placed in a uniform magnetic field of 0.16 T. The magnet is in stable equilibrium when the potential energy is
(a) 0.064 J
(b) –0.064 J
(c) zero
(d) –0.082 J 

Answer :  B

Question. A vibration magnetometer placed in magnetic meridian has a small bar magnet. The magnet executes oscillations with a time period of 2 sec in earth’s horizontal magnetic field of 24 microtesla. When a horizontal field of 18 microtesla is produced opposite to the earth’s field by placing a current carrying wire, the new time period of magnet will be
(a) 1 s
(b) 2 s
(c) 3 s
(d) 4 s

Answer :  D 

Question. A closely wound solenoid of 2000 turns and area of cross-section 1.5 × 10^–4 m² carries a current of 2.0 A. It is suspended through its centre and perpendicular to its length, allowing it to turn in a horizontal plane in a uniform magnetic field 5 × 10–2 tesla making an angle of 30° with the axis of the solenoid.
The torque on the solenoid will be
(a) 3 × 10^–3 N m
(b) 1.5 × 10^–3 N m
(c) 1.5 × 10^–2 N m
(d) 3 × 10^–2 N m

Answer :  C

Question. A bar magnet having a magnetic moment of 2 × 104 J T–1 is free to rotate in a horizontal plane. A horizontal magnetic field B = 6 × 10–4 T exists in the space. The work done in taking the magnet slowly from a direction parallel to the field to a direction 60° from the field is
(a) 12 J
(b) 6 J
(c) 2 J
(d) 0.6 J

Answer :  B

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. At a point A on the earth’s surface the angle of dip,d = +25°. At a point B on the earth’s surface the angle of dip, d = –25°. We can interpret that
(a) A and B are both located in the southern hemisphere.
(b) A and B are both located in the northern hemisphere.
(c) A is located in the southern hemisphere and B is located in the northern hemisphere.
(d) A is located in the northern hemisphere and B is located in the southern hemisphere.

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. 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. At a temperatur of 30°C, the susceptibility of a ferromagnetic material is found to be c . Its susceptibility at 333°C is 
(a) c
(b) 0.5 c
(c) 2c
(d) 11.1c

Answer :  B

Question. A thin diamagnetic rod is placed vertically between the poles of an electromagnet. When the current in the electromagnet is switched on, then the diamagnetic rod is pushed up, out of the horizontal magnetic field. Hence the rod gains gravitational potential energy.The work required to do this comes from
(a) the current source (b) the magnetic field
(c) the lattice structure of the material of the rod
(d) the induced electric field due to the changing magnetic field 

Answer :  A

Question. The magnetic moment of a diamagnetic atom is
(a) much greater than one
(b) 1
(c) between zero and one
(d) equal to zero 

Answer :  D

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 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. 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. Two points A and B are situated at a distance x and 2x respectively from the nearer pole of a magnet 2 cm long. The ratio of magnetic field at A and B is
(a) 4 : 1 exactly
(b) 4 : 1 approximately
(c) 8 : 1 approximately
(d) 1 : 1 approximately

Answer :  C

Question. An iron rod of susceptibility 599 is subjected to a magnetising field of 1200 A m^–1. The permeability of the material of the rod is (m0 = 4p × 10^–7 T m A^–1)
(a) 2.4p × 10^–4 T m A^–1
(b) 8.0 × 10^–5 T m A^–1
(c) 2.4p × 10^–5 T m A^–1
(d) 2.4p × 10^–7 T m A^–1

Answer :  A

Question. A bar magnet is oscillating in the Earth’s magnetic field with a period T. What happens to its period and motion if its mass is quadrupled ?
(a) Motion remains simple harmonic with time period = T/2
(b) Motion remains S.H.M with time period = 2T
(c) Motion remains S.H.M with time period = 4T
(d) Motion remains S.H.M and period remains nearly constant 

Answer :  B

Question. Two bar magnets having same geometry with magnetic moments M and 2M, are firstly placed in such a way that their similar poles are in same side then its time period of oscillation is T1. Now the polarity of one of the magnet is reversed then time period of oscillation is T2, then
(a) T1 < T2
(b) T1 = T2
(c) T1 > T2
(d) T2 = ∞ 

Answer :  A

Question. Nickel shows ferromagnetic property at room temperature. If the temperature is increased beyond Curie temperature, then it will show
(a) anti ferromagnetism
(b) no magnetic property
(c) diamagnetism
(d) paramagnetism. 

Answer :  D

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

Answer :  C

Question. Among which the magnetic susceptibility does not depend on the temperature?
(a) Diamagnetism
(b) Paramagnetism
(c) Ferromagnetism
(d) Ferrite. 

Answer :  A

Question. Among which the magnetic susceptibility does not depend on the temperature?     
(a) Diamagnetism
(b) Paramagnetism
(c) Ferromagnetism
(d) Ferrite. 

Answer    A

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

Answer    C

Question. A closely wound solenoid of 2000 turns and area of cross-section 1.5 × 10–4 m2 carries a current of 2.0 A.     
It is suspended through its centre and perpendicular to its length, allowing it to turn in a horizontal plane in a uniform magnetic field 5 × 10^–2 tesla making an angle of 30° with the axis of the solenoid.
The torque on the solenoid will be
(a) 3 × 10^–3 N m
(b) 1.5 × 10^–3 N m
(c) 1.5 × 10^–2 N m
(d) 3 × 10^–2 N m

Answer    C

Question. Nickel shows ferromagnetic property at room temperature. If the temperature is increased beyond Curie temperature, then it will show     
(a) anti ferromagnetism
(b) no magnetic property
(c) diamagnetism
(d) paramagnetism.

Answer    D

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