An electric current of `20 mu A` appears in a discharege tube if the discharge current is due to flow of equal number of electrons and protons then how many electrons flow across a cross-section of the tube in `2` minutes

Answer

`7.5 xx 10^(15)`

Explanation

Total charge flowing in two minutes
`q = It = (20 xx 10^(-6)A) xx (2 xx 60s) = 24 xx 10^(-4) C`
Charge flowing due to electron
`= (24 xx 10^(-4))/(2) = 12 xx 10^(-4)C`
No of electron flowing across-section of a tube is `2` minutes is
`n= (12 xx 10^(-4))/(1.6 xx 10^(-19)) = 7.5 xx 10^(15)`