Question

Calculate the drift velocity of the free electrons with mobility of 3.5×10^-3 m^2/Vs in copper for an electric field strength of 0.5 V/m.

(a) 3.5 m/s

(b) 1.75×10^3 m/s

(c) 11.5 m/s

(d) 1.75×10^-3 m/s

This question was addressed to me during an online interview.

My doubt stems from Free Electron Theory in chapter Semiconductors of Engineering Physics II

Answer 1

Correct answer is (d) 1.75×10^-3 m/s

To elaborate: Drift velocity = μE

Drift velocity = 3.5×10^-3×0.5 = 1.75×10^-3m/s.