# Questions On Magnetic Properties of Solids with Answers

## Questions On Magnetic Properties of Solids with Answers

Q1. The susceptibility of a diamagnetic material is:

• (A) Positive and proportional to temperature
• (B) Negative and inversely proportional to temperature
• (C) Negative and independent of temperature
• (D) Positive and inversely proportional to temperature.

Q2. The following are the plots of the temperature dependence of the magnetic susceptibility for three different samples. The plots A, B and C correspond to

• (A) Ferromagnet, paramagnet and diamagnet, respectively.
• (B) Paramagnet, diamagnet and ferromagnet, respectively
• (C) Ferromagnet, diamagnet and paramagnet, respectively
• (D) Diamagnet, paramagnet and ferromagnet, respectively.

Q3. The magnetic susceptibility χ of three samples A, B and C, is measured as a function of their absolute temperature T, leading to the graphs shown below. From these graphs, the magnetic nature of the samples can be inferred to be

• (A) A: anti-ferromagnet B: paramagnet C: ferromagnet
• (B) A: diamagnet B: paramagnet C: anti-ferromagnet
• (C) A: paramagnet B: anti-ferromagnet C: ferromagnet
• (D) A: anti-ferromagnet B: diamagnet C: paramagnet

Q4. A ferromagnetic material has a Curie temperature 100 K then,

• (A) Its susceptibility is doubled when it is cooled from 300 K to 200 K.
• (B) All the atomic magnets in it get oriented in the same direction above.
• (C) The plot of inverse susceptibility versus temperature is linear with a slope (Tc).
• (D) The plot of its susceptibility versus temperature is linear with an intercept Tc

Q5. An external magnetic field of magnitude H is applied to a type-I superconductor at temperature below the transition point. Then which one of the following statements is not true for H less than the critical field Hc ?

• (A) The sample is diamagnetic.
• (B) Its magnetization varies linearly with H.
• (C) The lines of magnetic induction are pushed out from the sample.
• (D) The sample exhibits mixed states of magnetization near Hc

Q6. The critical magnetic field for a solid in superconducting state

• (A) does not depend upon temperature
• (B) increases if the temperature increases
• (C) increases if the temperature decreases
• (D) does not depend on the transition temperature

Q7. The unit of magnetic moment is

• (A) erg-gauss
• (B) (erg gauss)-1
• (C) m-gauss
• (D) Bohr magneton

Q8. A permanent magnet when heated above a critical temperature becomes

• (A) diamagnetic
• (B) ferromagnetic
• (C) ferrimagnetic
• (D) paramagnetic

Q9. The magnetic material in which permanent magnetic dipoles arising due to electron spins are already aligned due to bonding forces is known as

• (A) paramagnetic material
• (B) ferromagnetic material
• (C) ferrimagnetic material
• (D) diamagnetic material

Q10. The susceptibility of a diamagnetic material is about

• (A) -10-5
• (B) 10-7
• (C) 102
• (D) 103

Q11. A solid sample has the property that, when cooled below a certain temperature, it expels any small applied magnetic field form within the material. Which of the following best describes this sample in the cooled state ?

• (A) Paramagnet
• (B) Diamagnet
• (C) Ferromagnet
• (D) Antiferromagnet

Q12. A paramagnetic gas at room temperature is placed in an external magnetic field of 1.5 T (tesla). Each atom of the gas has a magnetic moment μ = 1.0 μ’ , where μ’ = 9.3 × 10 J/T is the Bohr magneton. The difference in energy when an atom is aligned along the magnetic field and opposite to it, is

• (A) 2.8 × 10-23
• (B) 1.4 × 10-23
• (C) 18.6 × 10-24
• (D) 9.3 × 10-24 J

Q13. The dependencies of the magnetic susceptibility (χ) of a material with temperature (T) can be represented by χ ∝ 1/(T-θ) , where θ is the Curie-Weiss temperature. The plot of magnetic susceptibility versus temperature is sketched in the figure, as curve P, Q, and R with curve Q having θ = 0. Which one of the following statements is correct ?

• (A) curve R represents a paramagnet and Q a ferromagnet.
• (B) curve Q represents a ferromagnet and P an antiferromagnet.
• (C) curve R represents an antiferromagnet and Q a paramagnet.
• (D) curve R represents an antiferromagnet and Q a ferromagnetic.

Q14. The high temperature magnetic susceptibility of solids having ions with magnetic moments can be described by χ ∝ 1/(T + θ) where T as absolute temperature and eas constant. The three behaviors i.e., paramagnetic, ferromagnetic an antiferromagnetic are described, respectively, by

• (A) θ 0, θ = 0
• (B) θ > 0, θ < 0, θ = 0
• (C) θ = 0, θ 0
• (D) θ = 0, θ > 0, θ < 0

Q15. Very low temperatures can be produced by

• (A) Adiabatic demagnetisation of a paramagnetic salt
• (B) Adiabatic magnetisation of a paramagnetic salt
• (C) Isothermal magnetisation of diamagnetic salt
• (D) Isothermal demagnetisation of diamagnetic salt

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