Numerical problems on Drift velocity of electrons and electric current-how to solve?

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.

Solution:

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

Numerical problems on Drift velocity of electrons and electric current-how to solve?
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