We have compiled the NCERT MCQ Questions for Class 12 Physics Chapter 5 Magnetism and Matter with Answers Pdf free download covering the entire syllabus. Practice MCQ Questions for Class 12 Physics with Answers on a daily basis and score well in exams. Refer to the Magnetism and Matter Class 12 MCQs Questions with Answers here along with a detailed explanation.
Magnetism and Matter Class 12 MCQs Questions with Answers
Question 1.
The unit of pole strength is:
(a) Am-1
(b) Am
(c) Am-2
(d) Am²
Answer
Answer: (b) Am
Question 2.
The angle of dip at a place where the horizontal component of earth’s magnetic field equals the vertical component is:
(a) 45°
(b) 0°
(c) 90°
(d) 30°
Answer
Answer: (a) 45°
Question 3.
Isoclinic lines are the lines joining places of:
(a) equal dip
(b) equal declination
(c) 0° dip and 90° declination
(d) equal dip and declination both
Answer
Answer: (a) equal dip
Question 4.
Two identical magnets each of dipole moment M and length 21 are perpendicular to each other as shown in figure here. The dipole moment of the combination is
(a) √2 M
(b) 2M
(c) \(\frac {m}{√2}\)
(d) \(\frac {M}{2}\)
Answer
Answer: (a) √2 M
Question 5.
The Hysteresis cycle for the material of permanent magnet should be:
(a) long and thin
(b) short and thin
(c) short and wide
(d) long and wide
Answer
Answer: (d) long and wide
Question 6.
A steel wire of length l has a magnetic moment M. It is the bent into a semi circular arc. The new magnetic moment is:
(a) \(\frac {M}{l}\)
(b) M
(c) \(\frac {2}{π}\)
(d) M × l
Answer
Answer: (c) \(\frac {2}{π}\)
Question 7.
A magnetic needle lying parallel to a magnetic field requires W units of work to turn in through 60°. The torque needed to maintain the needle in this position will be:
(a) \(\frac {W}{√3}\)
(b) √3W
(c) \(\frac {2}{√3}\) W
(d) \(\frac {√3}{2}\) W
Answer
Answer: (b) √3W
Question 8.
The magnetic field due to a small magnetic dipole of magnetic moment M, at a distance r from its centre on the equitorial line is:
(a) \(\frac {µ_0}{4π}\) \(\frac {M}{r^3}\)
(b) \(\frac {µ_0}{4π}\) \(\frac {2M}{r^3}\)
(c) \(\frac {µ_0}{4π}\) \(\frac {2M}{r^2}\)
(d) \(\frac {µ_0}{4π}\) \(\frac {M}{r^2}\)
Answer
Answer: (a) \(\frac {µ_0}{4π}\) \(\frac {M}{r^3}\)
Question 9.
The magnetic fields strength at a distance d from a short bar magnet in longitudinal and transverse positions are in the ratio.
(a) 2 : 1
(b) 1 : 2
(c) 1 : 1
(d) 3 : 2
Answer
Answer: (a) 2 : 1
Question 10.
A long solenoid has 800 turns per metre length of solenoid. A current of 1.6 A flows through it. The magnetic induction at the end of the solenoid on its axis is:
(a) 32 × 10-4 T
(b) 16 × 10-4 T
(c) 4 × 10-4 T
(d) 8 × 10-4 T
Answer
Answer: (d) 8 × 10-4 T
Question 11.
The lines of force due to earth’s horizontal magnetic field are:
(a) Curved lines
(b) elliptical
(c) Parallel and straight
(d) concentric circles.
Answer
Answer: (a) Curved lines
Question 12.
Domain formation is the necessary feature of
(a) Diamagnetism
(b) Paramagnetism
(c) Ferromagnetism
(d) All of these.
Answer
Answer: (c) Ferromagnetism
Question 13.
Susceptibility of a magnetic substance is found to depend on temperature and the strength of the magnetising field. The material is a:
(a) Diamagnet
(b) Paramagnet
(c) Ferromagnet
(d) Superconductor.
Answer
Answer: (c) Ferromagnet
Question 14.
A uniform magnetic field is obtained in a:
(a) bar magnet
(b) horse shoe magnet
(c) circular coil carrying current
(d) None of these.
Answer
Answer: (a) bar magnet
Question 15.
A magnetic needle suspended by a silk thread is vibrating in the earth’s magnetic field. If the temperature of the needle is increased of 700°C, then
(a) time period increases.
(b) time period decreases.
(c) time period remains unchanged.
(d) the needle stops vibrating.
Answer
Answer: (d) the needle stops vibrating.
Question 16.
Isogonic lines on magnetic map represent lines of:
(a) Zero declination.
(b) equal declination.
(c) equal dip.
(d) equal horizontal field.
Answer
Answer: (b) equal declination.
Question 17.
At Curie point of ferromagnetic material becomes
(a) Diamagnetic
(b) Paramagnetic
(c) Strongly ferromagnetic
(d) non-magnetic
Answer
Answer: (b) Paramagnetic
Question 18.
The absence of magnetic monopole is explained by
(a) Gauss’s law
(b) Coulomb’s law
(c) Lorentz’s Law
(d) Fleming law.
Answer
Answer: (a) Gauss’s law
Fill in the Blanks
Question 1.
A wire of length l metre carrying a current I ampere is bent into a circle. The magnitude of the magnetic moment in S.I. system is ………………..
Answer
Answer: \(\frac {Il^2}{4π}\)
Question 2.
Lines joining the places having same angle of dip are called as ………………..
Answer
Answer: Isoclinic lines.
Question 3.
Angle between the magnetic meridian and the geographic meridian is called as ………………..
Answer
Answer: Angle of declination.
Question 4.
According to the modem theory of magnetism, every atom of a substance behaves just like a ………………..
Answer
Answer: bar magnet.
Question 5.
The vertical component of earth’s magnetic field exists every where except at the ………………..
Answer
Answer: Magnetic equator.
Question 6.
The electromagnets are made of soft iron because it has ……………….. and ………………..
Answer
Answer: Low coercivity, high permeability.
Question 7.
Soft iron is preferred as the core of transformers due to its ……………….., ……………….., ……………….. and ………………..
Answer
Answer: High retentivity, low coercivity, high permeability, low hystersis loss.
Question 8.
Lines joining the places having the same angle of declination are called ………………..
Answer
Answer: Isogonic lines.
Question 9.
In a hydrogen atom, the electron moves in an orbit of radius 0.5.0 A° making 1016 revolutions per second. The magnetic moment associated with the orbital motion of the electron is ………………..
Answer
Answer: 1.26 × 10-23 Am².
Question 10.
The area under B-H or I-H loop gives the energy dissipated as heat and is known as hysteresis loss which is equal to ………………..
Answer
Answer: loss of energy per unit volume per cycle of magnetisation.
Question 11.
The Angle of dip is 0° at ……………….. and 90° at ………………..
Answer
Answer: Magnetic equator, magnetic poles.
Question 12.
Ampere/metre (Am-1) or Newton per Tesla per metre2 (NT-1m-21) is the S.I. unit of ………………..
Answer
Answer: Magnetic intensity.
Question 13.
Ratio of force applied by the pole of a magnet on a unit north pole to the magnetic induction is called ………………..
Answer
Answer:
Pole strength (m) i.e.,
m = \(\frac {F}{B}\)
Question 14.
S.I. unit of magnetic permeability (µ) is ………………..
Answer
Answer: Wb A-1 m-1 or henry/metre (Hm-1).
Question 15.
The potential energy of a magnetic dipole is minimum when it is ……………….. to the magnetic field and maximum when it is ……………….. to the magnetic field.
Answer
Answer: Parallel, Antiparallel.
Question 16.
The magnetic dipole is in the unstable equilibrium when \(\vec{M}\) and \(\vec{B}\) are ……………….. and in the stable equilibrium when \(\vec{M}\) and \(\vec{B}\) are ………………..
Answer
Answer: Antiparallel, parallel.
Question 17.
The magnetic field inside a solenoid is ……………….. than inside a bar magnet.
Answer
Answer: stronger.
Question 18.
The magnetic field is ……………….. inside a solenoid and ……………….. outside it.
Answer
Answer: Uniform, non-uniform.
Question 19
……………….. is the surest test for a substance to be a magnet.
Answer
Answer: Repulsion.
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