Question

The drift speed of the conduction electrons is :

• A. 2.5 cm/s
• B. 5 cm/s
• C. 7.5 cm/s
• D. 15 cm/s

Answer 1

The correct option is A 2.5 cm/s

We have, $V=El=200\times 0.18=36V$

Thus we get, $J=\frac{I}{A}=\frac{V}{AR}=\frac{36}{2\times {10}^{-4}\times 900}=200A/m^2$

By applying a potential difference between its front and rear faces, an electric field of magnitude 200 V/m is produced inside the block and that will cause the carriers to move with drift velocity $V_d$. And , the current density is expressed in terms of $V_d$ and no of carriers $\left(n\right)$. i.e. $J=ne{V}_d$.

$V_d=\frac{J}{ne}=\frac{200}{5\times {10}^{22}\times 1.6\times {10}^{-19}}=2.5$ cm/s