Q. A wire $100cm$ long and $2.0\ mm$ diameter has a resistance of $0.7\ ohm,$ the electrical resistivity of the material is
A) $4.4 \times 10^{- 6}\ ohm \times m$
B) $2.2 \times 10^{- 6}ohm \times m$
C) $1.1 \times 10^{- 6}\ ohm \times m$
D) $0.22 \times 10^{- 6}\ ohm \times m$
Explanation
(b) $R = \frac{\rho L}{A} \Rightarrow 0.7 = \frac{\rho \times 1}{\frac{22}{7}\left( 1 \times 10^{- 3} \right)^{2}}$
$\rho = 2.2 \times 10^{- 6}ohm - m$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.