Match List-I with List-II.
| List-I | List-II |
|---|---|
| (A) Diamagnetism | (I) Atoms have permanent magnetic moments, but thermal motion keeps them in random directions. |
| (B) Paramagnetism | (II) The resultant magnetic moment of an atom is zero; an applied field induces a moment opposite to it. |
| (C) Ferromagnetism | (III) Field lines are completely expelled from a metal cooled to a very low temperature. |
| (D) Meissner effect | (IV) Atomic moments line up on their own in a common direction over regions called domains. |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (A)-(II), (B)-(I), (C)-(IV), (D)-(III)
(A) Diamagnetism — This matches (II). In a diamagnetic atom the orbital moments of the electrons add up to zero. An applied field changes the speeds of the orbiting electrons, so a net moment appears opposite to the field.
(B) Paramagnetism — This matches (I). Each atom has its own permanent moment. Random thermal motion keeps these moments in all directions, so there is no net magnetisation without a field.
(C) Ferromagnetism — This matches (IV). The atomic moments act on one another and line up by themselves over a domain. Each domain has a net magnetisation.
(D) Meissner effect — This matches (III). A superconductor is a metal at a very low temperature. It is a perfect diamagnet with \( \chi=-1 \), so it pushes out the field lines completely.
NCERT (2026-27):
Diamagnetism – “… Diamagnetic substances are the ones in which resultant magnetic moment in an atom is zero. … Thus, the substance develops a net magnetic moment in direction opposite to that of the applied field and hence repulsion.”
Paramagnetism – “The individual atoms (or ions or molecules) of a paramagnetic material possess a permanent magnetic dipole moment of their own. On account of the ceaseless random thermal motion of the atoms, no net magnetisation is seen. …”
Ferromagnetism – “… However, they interact with one another in such a way that they spontaneously align themselves in a common direction over a macroscopic volume called domain. …”
Diamagnetism – “… Here the field lines are completely expelled! χ= –1 and μr = 0. … The phenomenon of perfect diamagnetism in superconductors is called the Meissner effect, after the name of its discoverer. …”