83 free MCQs on Magnetism and Matter, each with its own worked answer and explanation. Bar magnets, Earth's magnetism, and how different materials respond to an external magnetic field - diamagnetic, paramagnetic, and ferromagnetic behaviour.
Take the timed Magnetism and Matter chapterwise test →83 practice questions on Magnetism and Matter, sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the Magnetism and Matter notes.
Magnetic field of a bar magnet: field lines emerge from the north pole and re-enter at the south pole outside the magnet, forming continuous closed loops. Image: Geek3, CC BY-SA 3.0, via Wikimedia Commons.
Q1.
The magnetic field lines of a bar magnet form:
Q2.
Which of these is a diamagnetic material?
Q3.
The magnetic declination at a place is the angle between:
Q4.
A permanent magnet is best made from a material that is magnetically:
Q5.
The magnetic susceptibility of a vacuum is:
Q6.
A magnetic pole that does not exist alone is called:
Q7.
Earth has a magnetic field. Geographic north corresponds to:
Q8.
Which of these elements is ferromagnetic at room temperature?
Q9.
What happens to a diamagnetic material when placed in an external magnetic field?
Q10.
The SI unit of magnetic moment is:
Q11.
What is the angle that the Earth's magnetic field makes with the horizontal called?
Q12.
Above the Curie temperature, a ferromagnetic material becomes:
Q13.
When a bar magnet is suspended freely and allowed to rotate, it eventually comes to rest pointing approximately:
Q14.
A material that gets weakly magnetised in a direction opposite to the applied magnetic field is called:
Q15.
The imaginary lines used to represent a magnetic field, drawn so that the tangent at any point gives the field direction, are called:
Q16.
A freely suspended bar magnet finally comes to rest pointing in the:
Q17.
Like magnetic poles placed near each other:
Q18.
Unlike magnetic poles placed near each other:
Q19.
An isolated single magnetic pole (a magnetic monopole):
Q20.
The region around a magnet where its influence is felt is called the:
Q21.
The SI unit of magnetic pole strength is the:
Q22.
The Earth as a whole behaves approximately like a giant:
Q23.
Magnetic field lines outside a magnet emerge from its ___ pole:
Q24.
Materials that are strongly attracted by a magnet are called:
Q25.
When a bar magnet is cut into two pieces, each piece:
Q26.
A diamagnetic substance placed in a non-uniform magnetic field tends to move:
Q27.
A bar magnet of moment 2 A m<sup>2</sup> is placed perpendicular to a uniform field of 0.25 T. The torque on it is:
Q28.
A paramagnetic sample has susceptibility 3 × 10<sup>-3</sup> at 300 K. By Curie's law, at 150 K its susceptibility becomes:
Q29.
At a place the horizontal component of Earth's field is 0.26 × 10<sup>-4</sup> T and the angle of dip is 60°. The total field is:
Q30.
The work done in rotating a magnetic dipole of moment m from alignment with a field B to a position perpendicular to it is:
Q31.
A magnetising field H = 800 A/m produces magnetisation M = 2.4 × 10<sup>5</sup> A/m in a material. Its susceptibility is:
Q32.
How does the magnetic susceptibility of a paramagnetic substance change as temperature increases?
Q33.
A bar magnet of magnetic moment m is placed in a uniform external field B at angle theta to the field. What is the potential energy of the magnet?
Q34.
Why does a superconductor behave differently from an ordinary diamagnetic material?
Q35.
Soft iron is preferred over steel for making transformer cores because soft iron has:
Q36.
A bar magnet is cut into two equal pieces along its axis (lengthwise, so each piece is thinner but the same length as the original). Compared to the original, the pole strength of each new piece is:
Q37.
A bar magnet placed in a uniform magnetic field experiences zero net force but, in general, a non-zero torque. This happens because:
Q38.
Curie's law states that the magnetic susceptibility of a paramagnetic material is:
Q39.
A magnetic compass shows zero dip at a certain location. This location is most likely close to:
Q40.
A hysteresis loop for a magnetic material shows the area enclosed by the B-H curve during one complete cycle of magnetisation and demagnetisation. This enclosed area represents:
Q41.
A bar magnet of magnetic moment m and a solenoid of the same size and magnetic moment are both suspended freely near each other. Compared to the bar magnet, the solenoid:
Q42.
The magnetic dipole moment of a bar magnet points from its:
Q43.
Diamagnetic materials are ___ by a magnetic field:
Q44.
Paramagnetic materials are ___ by a magnetic field:
Q45.
The magnetic susceptibility of a diamagnetic material is:
Q46.
The magnetic susceptibility of a ferromagnetic material is:
Q47.
Which of the following is a ferromagnetic material?
Q48.
The torque on a magnetic dipole of moment m in a uniform field B is:
Q49.
The relative permeability of a ferromagnetic material is:
Q50.
The angle of dip is 90° at the Earth’s:
Q51.
The angle of dip is 0° at the Earth’s:
Q52.
A short bar magnet of moment 0.4 A m<sup>2</sup> gives an axial (end-on) field at 0.2 m of (μ<sub>0</sub>/4π = 10<sup>-7</sup>):
Q53.
For the same short magnet (moment 0.4 A m<sup>2</sup>) the equatorial (broadside-on) field at 0.2 m is:
Q54.
A thin bar magnet of moment m is bent into a semicircle. Its new magnetic moment is:
Q55.
In a vibration magnetometer the time period is 3 s. If the magnetic moment of the needle is doubled while the field is unchanged, the new period is:
Q56.
In MRI machines, strong magnetic fields are used. A proton's Larmor frequency in 3 T field:
Q57.
Magnetic susceptibility of diamagnetic materials is:
Q58.
A ferromagnetic material loses its magnetisation as soon as a small external field is removed, while another retains strong magnetisation. What do these two materials represent, and why does only one retain magnetism?
Q59.
A short bar magnet of magnetic moment 0.5 J/T is placed at 30° with a uniform external magnetic field of 0.2 T. The torque acting on the magnet is approximately:
Q60.
A bar magnet has magnetic moment m and length 2l. It is cut into two equal halves with a cut perpendicular to its length, so each piece is half as long. The magnetic moment of each new piece is:
Q61.
A magnetic needle free to rotate in a vertical plane oriented along the magnetic meridian dips at an angle of 60° at a place where the horizontal component of Earth's field is 0.3 × 10⁻⁴ T. The vertical component of Earth's magnetic field at that place is approximately:
Q62.
A solenoid with a ferromagnetic core has a magnetising field H = 1500 A/m, producing a magnetic field B = 2.4 T inside the core. The relative permeability of the core material is approximately:
Q63.
Two identical magnetic dipoles of moment m each are placed at a separation r, one in the end-on (axial) position and one in the broadside-on (equatorial) position relative to a reference point at the same distance r. The ratio of the magnetic field at that point due to the axial arrangement to the field due to the equatorial arrangement is:
Q64.
A toroid with a ferromagnetic core has 1000 turns per metre and carries a current of 2 A. If the core has a magnetic susceptibility of 599, the magnetisation of the core material is approximately:
Q65.
A compass needle is placed at a point where the resultant magnetic field has equal horizontal and vertical components. The angle of dip at that point is closest to:
Q66.
Above its Curie temperature, a ferromagnetic material becomes:
Q67.
The potential energy of a magnetic dipole in a field is minimum when the dipole is aligned ___ the field:
Q68.
Curie’s law states that the susceptibility of a paramagnet is ___ the absolute temperature:
Q69.
The three elements of the Earth’s magnetism are declination, the angle of dip and the ___ component of the field:
Q70.
A material that retains its magnetism after the external field is removed is:
Q71.
Soft iron is preferred for electromagnet cores because it is:
Q72.
The magnetic field on the axis of a short bar magnet falls off with distance r as:
Q73.
The angle between the geographic meridian and the magnetic meridian is called the angle of:
Q74.
Hysteresis is the lagging of the ___ behind the magnetising field:
Q75.
The magnetic moment of both a current loop and a bar magnet is measured in:
Q76.
A bar magnet of magnetic moment m is cut into two equal pieces along its length (perpendicular to its axis). The magnetic moment of each piece is:
Q77.
Diamagnetic materials are characterized by a magnetic susceptibility that is:
Q78.
When a ferromagnetic material is heated above its Curie temperature, it becomes:
Q80.
A material has magnetic susceptibility 0.5. Its relative permeability is:
Q81.
A bar magnet in a uniform magnetic field experiences maximum torque when the angle between its moment and the field is:
Q82.
In a vibration magnetometer, the time period is T = 2π√(I/mB). If the magnetic field is made four times stronger, the period:
Q83.
The magnetic moment of a flat current-carrying coil of N turns, current I, and area A is:
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