Practicing Success

Target Exam

CUET

Subject

Physics

Chapter

Current Electricity

Question:

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 :

Options:

0.0116 mm

0.0367 mm

0.116 mm

0.367 mm

Correct Answer:

0.0367 mm

Explanation:

$A=\pi r^2=\rho l / R$    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