The numerical problems in this post are based on drift velocity of electrons and electric current. Electric Current is expressed as I = nAve
[ 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 m2 . The number density of copper is 8.5 x 1028 m-3 . Calculate the mean drift velocity of the electrons through the wire when the current is 1.4 A.
The equation to use: I = nAve
=> mean drift velocity = v = I/(nAe)…. ……… (1)
As per the problem statement, A=7.85 x 10-7 m2
n=8.5 x 1028 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.