A current of 3.2 mA flows through a conductor. If charge on an electron is -1.6 x 10^-19 coulomb, find the number of electrons that will pass each second through the cross section of that conductor.

Given,

Current (I) = 3.2 mA = 3.2 × 10^-3 A

Charge of one electron = -1.6 × 10^-19 coulomb

t = 1 s

Charge flowing through the conductor in one second

Charge (Q) = current (I) x time (t)

Substituting the values in the formula above we get,

Q = 3.2 x 10^-3 x 1 = 3.2 x 10^-3

Hence,

$\text{No. of electrons} = \dfrac{\text{Total charge flowing}}{\text{Charge on one electron}}$

$= \dfrac{3.2 \times 10^{-3}}{1.6 \times 10^{-19}} \\[0.5em] = 2 \times 10^{16} \\[0.5em]$

Therefore, the number of electrons that will pass each second through the cross section of that conductor = 2 x 10¹⁶