Question

Charge passing through a conductor of cross section area $A=0.3m^2$ is given by $q=3t^2+5t+2$ in coulomb, when $t$ is in second. What is the value of drift velocity at $t=2s$? (Given, $n=2\times {10}^{25}/m^3$)

• A. $0.77\times {10}^{-5}m/s$
• B. $1.77\times {10}^{-5}m/s$
• C. $2.08\times {10}^{-5}m/s$
• D. $0.57\times {10}^{-5}m/s$

Answer 1

Answer: (B)

$1.77\times {10}^{-5}m/s$

Given : $A=0.3m^2$ $n=2\times {10}^{25}/m^3$ $q=3t^2+5t+2$
$i=\frac{dq}{dt}=6t+5=17$
Drift velocity, $v_d=\frac{i}{neA}$
$=\frac{17}{2\times {10}^{25}\times 1.6\times {10}^{-19}\times 0.3}$
$=\frac{17}{0.96\times {10}^6}=1.77\times {10}^{-5}m/s$