A sample of each material in List-I is placed in an external magnetic field. Match List-I with the behaviour of the field lines in List-II.
| List-I | List-II |
|---|---|
| (A) Diamagnetic bar | (I) Field lines highly concentrated inside |
| (B) Paramagnetic bar | (II) Field lines completely expelled |
| (C) Ferromagnetic bar | (III) Field lines slightly concentrated inside |
| (D) Superconductor | (IV) Field lines slightly expelled |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A)-(IV), (B)-(III), (C)-(I), (D)-(II)
(A) Diamagnetic bar — This matches (IV). The lines are pushed out a little, and the field inside falls by only about one part in \( 10^{5} \).
(B) Paramagnetic bar — This matches (III). The lines gather inside, but the field rises only slightly.
(C) Ferromagnetic bar — This matches (I). It is strongly magnetised, so the lines crowd into it.
(D) Superconductor — This matches (II). It is a perfect diamagnet with \( \chi=-1 \), so no field line enters it.
NCERT (2026-27):
Diamagnetism – “… The field lines are repelled or expelled and the field inside the material is reduced. In most cases, this reduction is slight, being one part in 105.”
Paramagnetism – “… The field lines gets concentrated inside the material, and the field inside is enhanced. In most cases, this enhancement is slight, being one part in 105.”
Ferromagnetism – “Thus, in a ferromagnetic material the field lines are highly concentrated.”
Diamagnetism – “The most exotic diamagnetic materials are superconductors. … Here the field lines are completely expelled! …”