Q. When the current $i$ is flowing a conductor, the drift velocity is $v.$ If $2i$ current is flowed through the same metal but having double the area of cross-section, then the drift velocity will be
A) $v/4$
B) $v/2$
C) $v$
D) $4v$
Explanation
(c) $v_{d} = \frac{J}{ne} \Rightarrow v_{d} \propto J$ [current density]
$J_{1} = \frac{i}{A}$ and $J_{2} = \frac{2i}{2A} = \frac{i}{A} = J_{1};\ \therefore\left( v_{d} \right)_{1} = \left( v_{d} \right)_{2} = v$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.