Question

A current of 1.6 mA flows through a conductor if charge on an electron is -1.6* 10^-19 coulomb find the no. Of electrons that will pass each second through the cross section of that conductor

Answer 1

Current =1.6 mA=(1.6/1000) A=1.6×10⁻³ A
Time=1 sec
We know that,
Current=Charge/Time
⇒Charge=Current×Time
               =1.6×10⁻³ A × 1 sec
               =1.6×10⁻³ C                

Then,Charge of 1 electron=1.6×10⁻¹⁹ C
⇒1.6×10⁻¹⁹ C of charge constitutes 1 electron
⇒1 C of charge constitutes =1/(1.6×10⁻¹⁹)  electrons
⇒1.6×10⁻³ C of charge constitutes=(1.6×10⁻³)×[1/(1.6×10⁻¹⁹)]
                                                      =10⁻³/10⁻¹⁹
                                                      =10¹⁶

∴Hence,10¹⁶ electrons will pass each second through the cross section of that conductor.