Practice portal › Magnetism and Matter › Magnetisation and Magnetic Materials
Asked in GUJCET 2018 · Dia, para and ferromagnetism
Idea: which way a sample is pushed tells you the sign of its susceptibility χ, and how hard it is pushed tells you the size of χ.
A moment induced along the field (positive χ) is pulled towards the strong-field region; a moment induced against the field (negative χ) is pushed towards the weak-field region.
'Towards the strong field' therefore rules out a diamagnetic substance.
'Weak force' rules out a ferromagnetic substance: with χ of order 10³ those are dragged in strongly.
What is left is small and positive, χ of order 10⁻⁵ to 10⁻³: attracted towards the strong field, but only feebly.
So the substance is paramagnetic.
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