Matching Materials with Susceptibility (Match-the-Column)
Physics · Magnetism And Matter · NEET
For match-the-column questions, remember four fixed susceptibility (χ) ranges: diamagnetic has a small negative χ that lies between −1 and 0, paramagnetic has a small positive χ (0 < χ < a tiny number ε), ferromagnetic has a very large positive χ (χ ≫ 1), and a non-magnetic material has χ = 0. Memory hook: "Dia is Down (negative), Para is a small Plus, Ferro is Far up, Non is Nothing (zero)."
Susceptibility number line: diamagnetic sits in the small negative band (−1 to 0), non-magnetic is exactly 0, paramagnetic is a small positive value, and ferromagnetic is far to the right (χ ≫ 1). Use this picture to answer any match-the-column question.
Your doubts, answered
Is the susceptibility of a diamagnetic material equal to −1 or a range?
For most real diamagnetic materials χ is a very small negative number, around −10⁻⁵. But the full allowed RANGE in NCERT match-column questions is written as 0 > χ ≥ −1 (that is, χ can go from just below 0 down to −1). The value −1 is the special limit reached only by a perfect diamagnet (a superconductor showing the Meissner effect), where it pushes out all field. So in a match-column, 'diamagnetic' pairs with the range −1 ≤ χ < 0, not a single number.
How do I tell paramagnetic from ferromagnetic when both have positive χ?
Both are positive, but the SIZE is different. Paramagnetic χ is small: 0 < χ < ε where ε is a tiny positive number (χ ≈ +10⁻⁵). Ferromagnetic χ is huge: χ ≫ 1 (hundreds to thousands, like iron with χ ≈ 599 or more). So in a match-column, small-positive → paramagnetic, very-large-positive → ferromagnetic.
What susceptibility does a non-magnetic material have?
A truly non-magnetic material (like vacuum or an ideal material that does not respond at all) has χ = 0. It produces no magnetisation in an external field. In NEET match-column lists this is the option that pairs with χ = 0, which is neither positive nor negative.
Why is diamagnetic χ negative while para and ferro are positive?
Susceptibility is defined by M = χH, where M is the magnetisation set up in the material. In a diamagnetic material the induced magnetisation M points OPPOSITE to the applied field H, so the ratio M/H is negative. In paramagnetic and ferromagnetic materials M is ALONG H, so χ is positive. The sign of χ simply records whether the material aids or opposes the field.
⚠️ The NEET trap ✗ Diamagnetic → χ = −1 exactly, and non-magnetic → some small positive value. ✓ Diamagnetic → range 0 > χ ≥ −1 (small negative, −1 only for a perfect diamagnet). Non-magnetic → χ = 0 exactly, not a positive value. 🧠 NTA loves swapping 'χ = 0' (non-magnetic) with 'small positive χ' (paramagnetic). Read the range symbol carefully: '=' means non-magnetic, '0 < χ < ε' means paramagnetic.
Real NEET questions
2024
Match List-I with List-II: List-I (Material) A. Diamagnetic, B. Ferromagnetic, C. Paramagnetic, D. Non-magnetic. List-II (Susceptibility χ) I. χ = 0, II. 0 > χ ≥ −1, III. χ ≫ 1, IV. 0 < χ < ε (a small positive number).
A · A. A-II, B-I, C-III, D-IV
B · B. A-III, B-II, C-I, D-IV
C · C. A-IV, B-III, C-II, D-I
D · D. A-II, B-III, C-IV, D-I ✓
Solution: Match each material to its χ range. Diamagnetic has small negative χ, so A → II (0 > χ ≥ −1). Ferromagnetic has very large positive χ, so B → III (χ ≫ 1). Paramagnetic has small positive χ, so C → IV (0 < χ < ε). Non-magnetic has no response, so D → I (χ = 0). The pairing is A-II, B-III, C-IV, D-I, which is option D.
2016
The magnetic susceptibility is negative for:
A · A. diamagnetic material only ✓
B · B. paramagnetic material only
C · C. ferromagnetic material only
D · D. paramagnetic and ferromagnetic materials
Solution: Using M = χH: only in diamagnetic materials does the induced magnetisation M point opposite to the applied field H, making the ratio χ = M/H negative. Paramagnetic and ferromagnetic materials both have M along H, so their χ is positive. Hence χ is negative for diamagnetic material only, option A.
Solved Magnetism And Matter NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
For the match-column ranges, treat them at room temperature. Diamagnetic χ barely changes with temperature. Paramagnetic χ falls with rising temperature (Curie's law, χ ∝ 1/T). A ferromagnet loses its strong χ above its Curie temperature and becomes paramagnetic.
Is χ a unit or dimensionless?
Susceptibility χ is dimensionless. It comes from M = χH, and both M (magnetisation) and H (magnetic intensity) have the same unit, A/m, so their ratio has no unit.
How is χ linked to relative permeability μ_r?
They are related by μ_r = 1 + χ. So diamagnetic gives μ_r a little less than 1, paramagnetic a little more than 1, and ferromagnetic μ_r much greater than 1. This link is often tested alongside match-column questions.
