Question

What is the SI unit of resistivity?

• A. $\Omega$ m
• B. $\Omega$ m$^{-1}$
• C. $\Omega^{-1}$ m$^{-1}$
• D. $\Omega$ m$^{-2}$

Hint:

Resistivity is an intrinsic property; Conductivity ($\kappa$) is its reciprocal ($(\Omega \cdot m)^{-1}$).

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
We need to determine the SI unit for electrical resistivity (\( \rho \)).
Step 2: Key Formula or Approach:
Resistance \( R = \rho \frac{l}{A} \), where \( l \) is length and \( A \) is area.
Therefore, \( \rho = R \frac{A}{l} \).
Step 3: Detailed Explanation:
Units in the formula:
\( R \rightarrow \Omega \) (Ohm)
\( A \rightarrow m^2 \) (Square meter)
\( l \rightarrow m \) (Meter)
Unit of \( \rho = \Omega \times \frac{m^2}{m} = \Omega \text{ m} \).
Step 4: Final Answer:
The SI unit of resistivity is \( \Omega \) m.