Curie's Law & Curie Temperature — MH-CET Physics MCQs with Solutions
Free MH-CET Physics Curie's Law & Curie Temperature MCQs with step-by-step solutions (21 questions). Part of Magnetic Materials. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Curie's Law & Curie Temperature · easy · theory
Curie's law for a paramagnetic material states that the susceptibility is:
A. Independent of temperature
B. Proportional to the square of the temperature
C. Inversely proportional to the absolute temperature ✓ Correct
D. Directly proportional to the absolute temperature
Solution: $\chi = \dfrac{C}{T}$, where $C$ is the Curie constant of the material.
Q2 — Curie's Law & Curie Temperature · easy · theory
The Curie temperature of a ferromagnetic material is the temperature above which it:
A. Becomes superconducting
B. Loses all magnetic response
C. Becomes paramagnetic ✓ Correct
D. Becomes diamagnetic
Solution: Thermal agitation destroys the spontaneous domain alignment, leaving only weak paramagnetic behaviour.
Q3 — Curie's Law & Curie Temperature · hard · theory
Above the Curie temperature, the susceptibility of a ferromagnetic material follows:
A. Curie's law $\chi = \dfrac{C}{T}$ exactly
B. A linear increase with temperature
C. A temperature-independent law
D. The Curie-Weiss law $\chi = \dfrac{C}{T - T_c}$ ✓ Correct
Solution: The Weiss correction accounts for the residual interaction between neighbouring atomic moments.
Q4 — Curie's Law & Curie Temperature · medium · theory
The Curie temperature of iron is approximately:
A. $5000\text{ K}$
B. $273\text{ K}$
C. $373\text{ K}$
D. $1043\text{ K}$ ✓ Correct
Solution: That is about $770^\circ\text{C}$; above it iron ceases to be ferromagnetic.
Q5 — Curie's Law & Curie Temperature · medium · theory
A ferromagnetic material heated above its Curie temperature and then cooled below it:
A. Remains permanently paramagnetic
B. Melts
C. Regains its ferromagnetic properties ✓ Correct
D. Becomes diamagnetic
Solution: The transition is reversible: domains re-form spontaneously as the material cools below $T_c$.
Q6 — Curie's Law & Curie Temperature · easy · theory
In the relation $\chi = \dfrac{C}{T}$, the constant $C$ is called the:
A. Curie constant ✓ Correct
B. Weiss constant
C. Boltzmann constant
D. Permeability constant
Solution: It depends on the material, being proportional to the number density and the square of the atomic magnetic moment.
Q7 — Curie's Law & Curie Temperature · medium · theory
The magnetisation of a paramagnetic material decreases as temperature rises because:
A. Thermal agitation disturbs the alignment of atomic dipoles ✓ Correct
B. The material becomes diamagnetic
C. The atomic dipole moments themselves shrink
D. The applied field weakens
Solution: Random thermal motion competes with the aligning torque of the field, so a higher temperature means poorer alignment.
Q8 — Curie's Law & Curie Temperature · medium · theory
Unlike paramagnetism, diamagnetism is:
A. Present only above the Curie point
B. Observed only in metals
C. Essentially independent of temperature ✓ Correct
D. Strongly dependent on temperature
Solution: It arises from field-induced changes in electron orbits, a mechanism that thermal motion does not disrupt.
Q9 — Curie's Law & Curie Temperature · easy · numerical
The absolute temperature of a paramagnetic sample is doubled. Its susceptibility becomes:
A. Half as large ✓ Correct
B. Four times as large
C. Unchanged
D. Twice as large
Solution: By Curie's law $\chi \propto \dfrac{1}{T}$.
Q10 — Curie's Law & Curie Temperature · medium · numerical
A paramagnetic material has susceptibility $0.006$ at $300\text{ K}$. At $600\text{ K}$ its susceptibility is:
A. $0.003$ ✓ Correct
B. $0.0015$
C. $0.012$
D. $0.006$
Solution: $\chi \propto \dfrac{1}{T}$, so doubling the temperature halves the susceptibility.
Q11 — Curie's Law & Curie Temperature · medium · numerical
The susceptibilities of a paramagnetic sample at $200\text{ K}$ and $400\text{ K}$ are in the ratio:
A. $4 : 1$
B. $1 : 4$
C. $2 : 1$ ✓ Correct
D. $1 : 2$
Solution: $\dfrac{\chi_1}{\chi_2} = \dfrac{T_2}{T_1} = \dfrac{400}{200} = 2$.
Q12 — Curie's Law & Curie Temperature · medium · numerical
A paramagnetic material has susceptibility $0.01$ at $300\text{ K}$. Its Curie constant is:
A. $30\text{ K}$
B. $300\text{ K}$
C. $3\text{ K}$ ✓ Correct
D. $0.01\text{ K}$
Solution: $C = \chi T = 0.01 \times 300 = 3\text{ K}$.
Q13 — Curie's Law & Curie Temperature · medium · numerical
A paramagnetic material has Curie constant $3\text{ K}$. Its susceptibility at $500\text{ K}$ is:
A. $0.006$ ✓ Correct
B. $1500$
C. $0.01$
D. $0.06$
Solution: $\chi = \dfrac{C}{T} = \dfrac{3}{500} = 0.006$.
Q14 — Curie's Law & Curie Temperature · hard · numerical
A material has Curie constant $2\text{ K}$ and Curie temperature $1000\text{ K}$. By the Curie-Weiss law, its susceptibility at $1200\text{ K}$ is:
A. $0.0017$
B. $0.01$ ✓ Correct
C. $0.1$
D. $0.002$
Solution: $\chi = \dfrac{C}{T - T_c} = \dfrac{2}{1200 - 1000} = \dfrac{2}{200} = 0.01$.
Q15 — Curie's Law & Curie Temperature · hard · numerical
A paramagnetic sample has susceptibility $0.02$ at $300\text{ K}$. The temperature at which it falls to $0.01$ is:
A. $450\text{ K}$
B. $150\text{ K}$
C. $600\text{ K}$ ✓ Correct
D. $900\text{ K}$
Solution: $\chi T = $ constant, so $T_2 = \dfrac{0.02 \times 300}{0.01} = 600\text{ K}$.
Q16 — Curie's Law & Curie Temperature · hard · numerical
A paramagnetic material at $27^\circ\text{C}$ has susceptibility $\chi$. At $127^\circ\text{C}$ its susceptibility is:
A. $\chi$
B. $0.21\chi$
C. $1.33\chi$
D. $0.75\chi$ ✓ Correct
Solution: In kelvin the temperatures are $300$ and $400$, so $\chi' = \chi \times \dfrac{300}{400} = 0.75\chi$.
Q17 — Curie's Law & Curie Temperature · medium · numerical
Iron has a Curie temperature of about $1043\text{ K}$. At $1100\text{ K}$ it behaves as a:
A. Superconductor
B. Diamagnetic material
C. Paramagnetic material ✓ Correct
D. Ferromagnetic material
Solution: Above $T_c$ the domain structure is destroyed and only weak paramagnetism survives.
Q18 — Curie's Law & Curie Temperature · medium · numerical
A paramagnetic material has Curie constant $4.5\text{ K}$. Its susceptibility at $450\text{ K}$ is:
A. $0.1$
B. $0.001$
C. $0.01$ ✓ Correct
D. $100$
Solution: $\chi = \dfrac{4.5}{450} = 0.01$.
Q19 — Curie's Law & Curie Temperature · medium · numerical
The absolute temperature of a paramagnetic sample is doubled at constant applied field. Its magnetisation becomes:
A. Twice as large
B. Half as large ✓ Correct
C. Four times as large
D. Unchanged
Solution: At fixed $H$, $M = \chi H \propto \dfrac{1}{T}$.
Q20 — Curie's Law & Curie Temperature · medium · numerical
A ferromagnetic material is heated above its Curie temperature. Its susceptibility:
A. Drops sharply to a small positive value ✓ Correct
B. Rises sharply
C. Remains unchanged
D. Becomes negative
Solution: It falls from the very large ferromagnetic value to the small paramagnetic one.
Q21 — Curie's Law & Curie Temperature · medium · numerical
A paramagnetic material has susceptibility $0.008$ at $500\text{ K}$. At $250\text{ K}$ its susceptibility is:
A. $0.016$ ✓ Correct
B. $0.002$
C. $0.008$
D. $0.004$
Solution: Halving the temperature doubles the susceptibility: $\chi = 0.008 \times \dfrac{500}{250} = 0.016$.