A wire 250 cm long and $1 mm^2$ in cross-section carries a current of 4 A when connected to a 2 V battery. The resistivity of the wire is
Answer & explanation
Correct answer: option 1
$ R = \frac{V}{I} = 0.5 \Omega$
$ R = \frac{\rho l}{A} $
$\Rightarrow \rho = \frac{RA}{l} = 0.2\times 10^{-6} \Omega-m$