Question

What is susceptibility of a medium, if its relative permeability is 0.85?

• A. 1.85
• B. 0.15
• C. \(-0.15\)
• D. \(-0.85\)

Hint:

Remember: \(\mu_r = 1 + \chi\). For diamagnetic materials, \(\mu_r < 1\) and \(\chi\) is negative.

Answer 1

The Correct Option is C

Step 1: Note the given value.
The relative permeability of the medium is $\mu_r = 0.85$. We must find the magnetic susceptibility $\chi$.

Step 2: Recall the link.
These two quantities are tied together by the simple relation $\mu_r = 1 + \chi$.

Step 3: Rearrange for chi.
Move the one across: $\chi = \mu_r - 1$.

Step 4: Substitute the number.
$\chi = 0.85 - 1$.

Step 5: Do the subtraction.
$\chi = -0.15$.

Step 6: Read the meaning.
A negative susceptibility tells us the material is diamagnetic, which gently pushes magnetic field out.
\[ \boxed{\chi = -0.15} \]