NEET
- Exam
- NEET
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- Physics
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- Magnetic Properties of Matter
NEET · Physics · Magnetic Properties of Matter
Given below are two statements: one is labelled as Assertion (A)...
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): The magnetic susceptibility of a diamagnetic substance is practically independent of temperature, whereas that of a paramagnetic substance is inversely proportional to absolute temperature.
Reason (R): Diamagnetism arises due to the orbital motion of electrons which is unaffected by thermal agitation, while paramagnetism involves the alignment of intrinsic permanent magnetic dipoles which is disrupted by thermal agitation.
In the light of the above statements, choose the most appropriate answer from the options given below:
Assertion (A): The magnetic susceptibility of a diamagnetic substance is practically independent of temperature, whereas that of a paramagnetic substance is inversely proportional to absolute temperature.
Reason (R): Diamagnetism arises due to the orbital motion of electrons which is unaffected by thermal agitation, while paramagnetism involves the alignment of intrinsic permanent magnetic dipoles which is disrupted by thermal agitation.
In the light of the above statements, choose the most appropriate answer from the options given below:
Options
- ABoth (A) and (R) are correct and (R) is the correct explanation of (A)
- BBoth (A) and (R) are correct but (R) is not the correct explanation of (A)
- C(A) is correct but (R) is not correct
- D(A) is not correct but (R) is correct
Correct answer
A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
Step-by-step solution
Assertion (A) is correct because the susceptibility of diamagnetic materials does not depend on temperature, while paramagnetic materials follow Curie's law ().
Reason (R) is also correct and explains (A). Diamagnetism is an inherent property of all atoms arising from the induced change in the orbital motion of electrons when a magnetic field is applied (Lenz's law). This induced moment is independent of the thermal motion of atoms. In contrast, paramagnetism requires the presence of permanent magnetic dipoles. An external magnetic field tends to align these dipoles, but random thermal agitation (proportional to ) opposes this alignment. Hence, as temperature increases, the alignment decreases, making susceptibility inversely proportional to temperature.
Answer: Both (A) and (R) are correct and (R) is the correct explanation of (A)
Reason (R) is also correct and explains (A). Diamagnetism is an inherent property of all atoms arising from the induced change in the orbital motion of electrons when a magnetic field is applied (Lenz's law). This induced moment is independent of the thermal motion of atoms. In contrast, paramagnetism requires the presence of permanent magnetic dipoles. An external magnetic field tends to align these dipoles, but random thermal agitation (proportional to ) opposes this alignment. Hence, as temperature increases, the alignment decreases, making susceptibility inversely proportional to temperature.
Answer: Both (A) and (R) are correct and (R) is the correct explanation of (A)