Question

A wire 1.2 mm in diameter and 32 cm long, carries a current of 648 mA. The density of free electrons in the wire is 5.90 × 10²⁸ m^-3. The drift velocity of electrons in the wire is:

1. 3.2 × 10^-5 m/s
2. 6.1 × 10-5 m/s
3. 1.8 × 10^-4 m/s
4. 3.6 × 10-4 m/s

Answer 1

Correct Answer - Option 2 : 6.1 × 10-5 m/s

Given:

d = 1.2 mm

L = 32 cm

I = 648 mA

n = 5.90 × 1028 m-3

We know that,

We know I = n AeVd

A = Cross sectional area in which electric field exist

Vd = Drift velocity

\(\therefore {V_d} = \frac{I}{{nAe}} = \frac{{648 \times {{10}^{ - 3}}}}{{5.90 \times {{10}^{28}} \times \frac{\pi }{4} \times {{\left( {1.2 \times {{10}^{ - 3}}} \right)}^2} \times 1.6 \times {{10}^{ - 19}}}}\)

= 6.1 × 10-5 m/s