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Which statement about relative magnetic permeability (μr) is incorrect?

1. It is a dimensionless ratio.
2. Its value is 1 for vacuum.
3. In ferromagnetic substances, μr is greater than 1.
4. In paramagnetic substances, μr is less than 1.

Correct answer: In paramagnetic substances, μr is less than 1.

Solution

The statement is incorrect because in paramagnetic substances, the relative magnetic permeability (μr) is actually slightly greater than 1, indicating that they have a weak positive response to an external magnetic field.

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