Question

Which of the following statements is INCORRECT for diamagnetic materials?
a. Relative permeability is less than one.
b. Magnetic susceptibility is negative and low.
c. Magnetic susceptibility does not depend on the temperature.
d. Magnetic susceptibility is positive and low.

• A. d
• B. a
• C. c
• D. b

Hint:

Diamagnetic materials have small negative susceptibility, independent of temperature.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
A diamagnetic material is weakly magnetised opposite to the applied field.

Step 2: Susceptibility
So its magnetic susceptibility \(\chi\) is small and negative. Statement b is correct and statement d (positive) is incorrect.

Step 3: Permeability
Since \(\mu_r=1+\chi\) with \(\chi<0\), the relative permeability is slightly less than one. Statement a is correct.

Step 4: Temperature
The effect comes from induced changes in electron orbital motion, which thermal agitation does not affect, so \(\chi\) does not depend on temperature. Statement c is correct. The incorrect statement is d, option (A).

Final Answer:
The incorrect statement is d, that susceptibility is positive and low. \[ \boxed{\text{(A) }\text{Statement d}} \]