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Experimentally, one finds that the magnetisation of a paramagnetic material is ______ proportional to applied magnetic field and ______ proportional to the absolute temperature.

Asked in GSEB Board March 2022 · Magnetisation, intensity and susceptibility

Answer: (1) directly, inversely

Step-by-step solution

Idea: two things compete inside a paramagnet. The applied field tries to line the atomic moments up; thermal agitation keeps knocking them out of line.

A stronger field aligns a bigger fraction of the moments, so the magnetisation grows with the field.

A higher temperature shakes the moments harder, so the same field aligns a smaller fraction and the magnetisation falls.

Experiment sums this up as Curie's law, M=CB/T, or equivalently χ=C/T, with T the absolute temperature.

So M is directly proportional to the applied field and inversely proportional to the absolute temperature.

Why the other options are wrong

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