A nichrome wire $1 m$ long and $1 mm^2$ in cross-section area draws 4 ampere at 2 volt. The resistivity of nichrome is
Answer & explanation
Correct answer: option 4
Resistance = $\frac{V}{I}$ = 0.5 A
R = $\frac{\rho l}{A}$ = 0.5 A
$\rho = \frac{0.5 \times 10^{-6}}{1} = 5 \times 10^{-7}\Omega$-m