Question

Point out the correct set of diamagnetic substances.
A. aluminium, sodium calcium and oxygen
B. bismuth, copper, lead and silicon
C. cobalt, nickel, gadolinium and aluminium
D. silver, niobium, magnesium and calcium

Answer 1

Hint: Electrostatics and magnetism are analogous in many ways. The formulas we derive in electrostatics can mostly be used in magnetism like formulas for electric dipole and formulas for magnetic dipole, but with slight changes. The method of induction works in both electrostatics and magnetism and it justifies our solution
Formula used:
$B = \mu H$

Complete answer:
When we place a nonmagnetic material which can be magnetized in an external magnetic field then there will be magnetic property induced in it. One noticeable thing over here is the amount of magnetic strength induced will be greater or lesser than the original applied magnetic field. That means the magnetism induction (B) in that material depends upon the intensity of magnetic field(H) and intensity of magnetization(I).
This question is related to the induction of magnetism in diamagnetic material by applying an external magnetic field. The magnetic flux density in the ferromagnetic material is given by $B = \mu H$
Where $\mu $ is the magnetic permeability which depends on susceptibility. For diamagnetic substances, susceptibility is negative. So permeability will be less than permeability due to free space. Hence induced magnetic fields will be less than the applied magnetic field.
From the above options bismuth, copper, lead and silicon are diamagnetic substances.

Hence option B is correct.

Note:
As far as magnetism is considered basically there are three kinds of magnetic materials, diamagnetic and paramagnetic and ferromagnetic. In diamagnetic the induction of poles will be in the opposite direction.. Same type of pole will be induced at the side which is near the magnetic pole and hence diamagnetic substances repel from the magnets.