Answer to Question #155029 in Physics for Jovi

Question

A peice of copper and a peice of silicon have exactly thesame diamention and are carrying thesame current (100mil amper). Given that the average drift velocity of electron in the copper wire is 2.0×10^-15 meter per second.what is the drift speed of electron in the silicon( ncu=8×10^28m^3 and nsi= 3×10^18m^3)

Answer 1

First, remember how we express the current in terms of concentration n, charge e, the velocity v, and area A:

$$I=nevA.$$

Since the currents, charge, and dimensions are the same, we have

$$\frac{n_\text{Cu}v_\text{Cu}}{n_\text{Si}v_\text{Si}}=1,\\\space\\ v_\text{Si}=\frac{n_\text{Cu}}{n_\text{Si}}v_\text{Cu}=5.33\cdot10^{-5}\text{ m/s}.$$