A copper wire of length $2.0,$m and cross‑sectional area $1.5,$mm${}^2$ has resistivity $1.68\times 10^{-8},\Omega \text{-m}$ at $20^{\circ }$C. What is its resistance?

Step-by-step solution

1. 1. Convert area to square metres: $1.5,$mm${}^2=1.5\times 10^{-6},{\text{m}}^2$.
2. 2. Use $R=\rho ,L/A$ with $\rho =1.68\times 10^{-8},\Omega \text{-m}$, $L=2.0,$m, $A=1.5\times 10^{-6},{\text{m}}^2$.
3. 3. Compute $R=\frac{1.68\times 10^{-8}\times 2.0}{1.5\times 10^{-6}}=2.24\times 10^{-2},\Omega =0.028,\Omega$.
4. 4. The answer is $0.028,Omega$.

Concept tested: Ohm’s law and resistivity

Published 3 September 2026 · Last updated 16 September 2026 · How this solution was prepared and checked