Question

Calculate the drift speed of the electrons when $1\text{A}$ of current exists in a coper wire of cross-section $2{\text{mm}}^2$. The number of free electrons per unit volume is $8.5\times {10}^{22}$.

• A. $36.8\text{m/s}$
• B. $36.8\text{mm/s}$
• C. $63.8\text{m/s}$
• D. $63.8\text{mm/s}$

Answer 1

The correct option is A $36.8\text{m/s}$

We know that,
$i=neA{v}_d$

$\Rightarrow v_d=\frac{i}{neA}=\frac{1}{8.5\times {10}^{22}\times 1.6\times {10}^{-19}\times 2\times {10}^{-6}}$

$\Rightarrow v_d=36.8\text{m/s}$