A current of 1A flows in a wire carried by electrons. How many electrons pass through the a cross-section of the wire each second?

One ampere is the current that passes through a wire’s cross section per second when one coulomb charged passes through it.

Charge of electron, e=1.6X10-19C

Let’s say that 1C charges contain n electrons.

ne=1C

n=1/(1.6X10^-19)=6.25X10^18. This is the number of electrons that pass through the cross section of a wire carrying 1A.