Match List-I with List-II
| List-I | List-II | ||
|---|---|---|---|
| (A) | Magnetisation \( (M) \) | (I) | \( \mu_{0}(1+\chi_{m}) \) |
| (B) | Magnetic susceptibility \( (\chi_{m}) \) | (II) | \( \mu H \) |
| (C) | Magnetic permeability \( (\mu) \) | (III) | Dimensionless, may be positive or negative |
| (D) | Magnetic induction \( (B) \) | (IV) | Net magnetic moment per unit volume |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A) - (IV), (B) - (III), (C) - (I), (D) - (II)
These are the basic quantities that describe a magnetic material in a field of intensity \( H \).
(A) Magnetisation \( (M) \) — this matches (IV) Net magnetic moment per unit volume. This is the definition of magnetisation: \( M = m_{\mathrm{net}}/V \).
(B) Magnetic susceptibility \( (\chi_{m}) \) — this matches (III) Dimensionless, may be positive or negative. \( \chi_{m} = M/H \) is a ratio of two quantities with the same unit (A/m), so it has no dimensions. It is negative for diamagnetic and positive for paramagnetic and ferromagnetic materials.
(C) Magnetic permeability \( (\mu) \) — this matches (I) \( \mu_{0}(1+\chi_{m}) \). From \( B = \mu_{0}(H + M) = \mu_{0}(1 + \chi_{m})H \), the permeability is \( \mu = \mu_{0}(1 + \chi_{m}) = \mu_{0}\mu_{r} \).
(D) Magnetic induction \( (B) \) — this matches (II) \( \mu H \). The same relation gives \( B = \mu H \).
NCERT (2026-27):
Magnetisation and Magnetic Intensity – “… We define magnetisation M of a sample to be equal to its net magnetic moment per unit volume:
\( \displaystyle \mathbf{M} = \frac{\mathbf{m}_{net}}{V} \qquad (5.7) \)”
Magnetisation and Magnetic Intensity – “… where \( \chi \), a dimensionless quantity, is appropriately called the magnetic susceptibility. … \( \chi \) is small and positive for materials, which are called paramagnetic. It is small and negative for materials, which are termed diamagnetic.”
Magnetisation and Magnetic Intensity – “… From Eqs. (5.12) and (5.13) we obtain,
\( \displaystyle \mathbf{B} = \mu_0 (1+\chi)\mathbf{H} \qquad (5.14) \)
\( \displaystyle = \mu_0 \mu_r \mathbf{H} = \mu \mathbf{H} \qquad (5.15) \)
… The magnetic permeability of the substance is \( \mu \) and it has the same dimensions and units as \( \mu_0 \); \( \mu = \mu_0 \mu_r = \mu_0 (1+\chi) \).”