question_answer

Drift speed of electrons, when \[1.5\text{ }A\] of current flows in a copper wire of cross section \[5\text{ }m{{m}^{2}}\], is v. If electron density in copper is \[9\times {{10}^{28}}/{{m}^{3}}\] the value of v in mm/s is close to (Take charge of electron to be \[=\text{ }1.6\times {{10}^{-19}}C)\] [JEE Main 09-Jan-2019 Morning]

A)             0.02

B) 0.2

C)             3

D) 2

Correct Answer: A

Solution :

[a]   Since

Option [a] is correct.