Drift speed of electrons, when 1.5   A current flows in a copper wire of cross section 5   mm 2 is…

Drift speed of electrons, when 1.5 A current flows in a copper wire of cross section 5 mm2 is vd. If the electron density in copper is 9×1028 m-3 the value of vd in mm s-1 is close to (Take charge of an electron to be =1.6×10-19 C)
  1. 0.2
  2. 3
  3. 2
  4. 0.02

Solution

Given,

Current, i=1.5 A,

Cross-section of the wire, A=5×10-6 m2 and

Electron density, n=9×1028 m-3.

As current, i=neAvd

⇒1.5=9×1028×1.6×10-19×5×10-6×vd

⇒vd=0.02 mm s-1.

Asked in: JEE Main 2019 (09 Jan Shift 1)

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