Question

What is the SI unit of resistivity?

• A. \(\Omega \mathrm{m}\)
• B. \(\Omega \mathrm{m}^{-1}\)
• C. \(\Omega ^{-1}\text{ }\mathrm{m}^{-1}\)
• D. \(\Omega \mathrm{m}^{-2}\)

Hint:

Resistivity is resistance times area divided by length.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
\(R=\rho\dfrac{l}{A}\), so \(\rho=\dfrac{RA}{l}\).

Step 2: Units
The unit of \(R\) is \(\Omega\), of \(A\) is \(\text{m}^{2}\) and of \(l\) is \(\text{m}\).
\(\rho=\dfrac{\Omega\,\text{m}^{2}}{\text{m}}=\Omega\,\text{m}\)

Step 3: Conclusion
The SI unit of resistivity is ohm metre.

Final Answer:
The SI unit of resistivity is ohm metre. \[ \boxed{\text{(A) }\Omega\,\text{m}} \]