A copper wire has a resistance of `10Omega` and an area of cross-section `1 m m^(2)`. A potential difference of 10 V exists across the wire. Calculate the drift speed of electrons if the number of electrons per cubic metre in copper is `8xx10^(28)` electrons.

Explanation

Here, `R=10Omega, A=1 mm^(2)=10^(-6)m^(2), V=10V, n=8xx10^(28)"electrons/m"^(3)`
Now, `I=enAv_(d)`
`therefore (V)/(R )=enAv_(d)" " (or) v_(d)=(V)/(enAR)`
`=(10)/(1.6xx10^(-19)xx8xx10^(28)xx10^(-6)xx10)=0.078xx10^(-3)ms^(-1)`
`=0.078xx m ms^(-1)`