KCET2011PhysicsCurrent Electricity
A conductor wire having 10²⁹ free electrons / m ³ carries a current of 20 ~A . If the cross-section of the wire is 1 ~mm ² , then the drift velocity of electrons will be (e=1.6 10⁻¹⁹ C )
Options
- A1.25 10⁻⁴ ~ms ⁻¹
- B1.25 10⁻³ ~ms ⁻¹
- C1.25 10⁻⁵ ~ms ⁻¹
- D6.25 10⁻³ ~ms ⁻¹
Correct answer
B. 1.25 10⁻³ ~ms ⁻¹
Step-by-step solution
Current, I=n A e v_ d Drift velocity v_ d = I n A e = 20 10²⁹ 10⁻⁶ 1.6 10⁻¹⁹ v_ d =1.25 10⁻³ ~ms ⁻¹