Question

In copper, each copper atom releases one electron. If a current of 1.1 A is flowing in the copper wire of uniform cross-sectional area of diameter 1 mm, then drift velocity of electrons will approximately be: (Density of copper = 9 × 10³ kg /m³, Atomic weight of copper = 63)

Options

• 10.3 mm/s

• 0.1 mm/s

• 0.2 mm/s

• 0.2 cm/s

Answer 1

0.1 mm/s

Explanation:

Given I = 1.1 A

e = 1.6 × 10^-19 C

A = πr² = π × (0.5 × 10^–3)² cm²

Electron density n

= `("N"_"A"rho)/"M"`

= `((6.023xx10^2)^3(9xx10^3))/(63xx10^-3)`

= 0.86 × 10²⁹ m^-3

Drift velocity v_d = `1/"neA"`

v_d = `1.1/(0.86xx10^29xx1.6xx10^-19 xxpi(0.5xx10^-3)^2)`

v_d = 0.1 × 10^-3 m/s

= 0.1 mm/s