Two wires, one of copper and another of iron, have the same diameter and can carry the same current. In which wire the drift velocity of electrons will be more?
The drift velocity of electrons in a conductor is given by,
\(v_d=\frac I{neA}\)
Where,
I = current in the conductor,
e = electric charge and
n = electron concentration
A = area of cross-section of the wire.
For a copper and an iron wire; ni < nc. i.e., the free electron density of copper is greater than the free electron density of iron. So, the drift velocity of electrons for iron is greater than copper wire.
Free electron density of iron is almost double of copper. So drift velocity of copper is greater than that of iron.
We know,
I= Vd enA
Or, Vd= I/enA
We can see drift velocit is inversely proprtional to the free electron density.
Free electron density of iron is almost double of copper, so drift velocity of electrons in copper is greater than of iron.
