The numerical problems in this post are based on drift velocity of electrons and electric current. Electric Current is expressed as *I *= *nAv*e

[ see the derivation of electric current and drift velocity equation]

**Numerical problems on Drift velocity of electrons and electric current**

**1 ] A copper wire has a cross sectional area of 7.85 x 10 ^{-7} m^{2} . The number density of copper is 8.5 x 10^{28} m^{-3} . Calculate the mean drift velocity of the electrons through the wire when the current is 1.4 A.**

Solution:

The equation to use: *I *= *nAv*e

=> **mean drift velocity = v = I/(nAe)…. ……… (1)**

As per the problem statement, A=7.85 x 10^{-7} m^{2}

n=8.5 x 10^{28} m^{-3}

and I = 1.4 A

We know, e=1.6 x 10^{-19}

Putting all the values in equation 1, we will get:

v= 1.31 x 10^{-4} m/s

Anupam M is a Graduate Engineer (NIT Grad) who has 2 decades of hardcore experience in Information Technology and Engineering. He is an avid Blogger who writes a couple of blogs of different niches. He loves to teach High School Physics and utilizes his knowledge to write informative blog posts on related topics. Anupam M is the founder and author of PhysicsTeacher.in Blog.