Read the following statements regarding the magnetic properties of materials: (I) For a perfect diamagnet (such as a superconductor), the magnetic susceptibility is = -1 and relative permeability is _r = 0 . (II) For paramagnetic materials, the relative permeability _r is slightly less than 1 . (III) For ferromagnetic materials, the magnetic susceptibility is large and positive, and _r . (IV) Diamagnetic materials ha

Step-by-step solution

Statement (I) is correct: A superconductor exhibits perfect diamagnetism (Meissner effect), where = -1 and _r = 1 + = 0 . Statement (II) is incorrect: For paramagnetic materials, is small and positive, so _r = 1 + is slightly greater than 1 . Statement (III) is correct: For ferromagnetic materials, 1 . Since _r = 1 + , it follows that _r . Statement (IV) is incorrect: Diamagnetic materials have a small negative magnetic susceptibility ( -1 Therefore, exactly two statements are correct. Answer: Only two