Q. There is a current of 0.21 A in a copper wire whose area of cross-section is $10^{- 6}m^{2}$. If the number of free electrons per $m^{3}$ is 8.4$\times 10^{28}$, then find the drift velocity, $(e = 1.6 \times 10^{- 19}C)$
A) $2 \times 10^{- 5}\ ms^{- 1}$
B) $1.56 \times 10^{- 5}\ ms^{- 1}$
C) $1 \times 10^{- 5}\ ms^{- 1}$
D) $0.64 \times 10^{- 5}\ ms^{- 1}$
Explanation
(b) $v_{d} = i/nAe$
$= 0.21/(8.4 \times 10^{28} \times 10^{- 6} \times 1.6 \times 10^{- 19})$
$= 1.56 \times 10^{- 5}ms^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.