Question

Diamagnetic materials are:

• A. Attracted by magnetic field
• B. Repelled by magnetic field
• C. Neutral
• D. Strongly attracted

Hint:

Superconductors are perfect diamagnets ($\chi = -1$).
They exhibit the Meissner effect, repelling all magnetic flux lines, which allows for stable magnetic levitation.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
This question asks about the qualitative physical response of diamagnetic materials when they are subjected to an external magnetic field.

Step 2: Key Formula or Approach:
The magnetic susceptibility ($\chi$) is defined as:
\[ \chi = \frac{M}{H} \] For diamagnetic materials, the susceptibility is a small, negative constant ($\chi < 0$), which indicates that the induced magnetization opposes the applied magnetic field.

Step 3: Detailed Explanation:

• Diamagnetism is a fundamental form of magnetism that occurs in all materials, though it is often very weak and easily dominated by other magnetic effects.

• It is prominent in materials that have completely filled electron shells (no unpaired electrons), meaning they lack permanent net magnetic moments.

• When an external magnetic field is applied, the orbital motion of the electrons is slightly modified to create a microscopic current.

• According to Lenz's law, this induced current creates an internal magnetic field that opposes the applied external field.

• This opposing magnetic field results in a weak mechanical repulsive force.

• Consequently, diamagnetic materials are repelled by an external magnetic field. Common examples include water, copper, and bismuth.

Step 4: Final Answer:
Diamagnetic materials are repelled by a magnetic field, which is option (B).