Question

What current in a copper wire with a cross-sectional area of 7.10 10-7 m2 would result in a drift speed equal to 5.09 10-4 m/s?

Answer 1

Drift velocity - current relation is

Where,

v_d is drift speed,

I is current,

n is electron number density,

q is the charge on an electron and

A is the cross-sectional area of the conductor.

Now, we need to calculate electron number density in copper

The density of the copper = 8.94 g/cm³.

The Atomic weight of the copper = 63.546 g/mol.

The atomic number density of the copper =Na x 8.94 / 63.546=8.47 x 10²⁸ atoms/m³.

We have one free electron per atom in copper, So,

Now,