A resistance of 2Ω is to be made from a copper wire (specific resistance 1.7 × 10-8 Ωm) using a wire of length 50 cm. The radius of the wire is :
Answer & explanation
Correct answer: option 2
$A=\pi r^2=\rho l / R$ or $R=(\rho l / \pi r)^{1 / 2}$
or r = $\left(\frac{1.7 \times 10^{-8} \times 0.5}{3.14 \times 2}\right)^{1 / 2}$ or r = 0.0367 mm