Due to what is current formed in an electrolyte?

$A$ current of $1\, mA$ is flowing through a copper wire. How many electrons will pass a given point in one second?

$A$ steady current flows in a metallic conductor of non-uniform cross-section. Which of the following quantities is constant along the conductor?

$A$ copper rod of cross-sectional area $A$ carries a uniform current $I$ through it. At temperature $T$,if the volume charge density of the rod is $\rho$,how long will the charges take to travel a distance $d$?

Define electric current when there is no steady flow of charge.

Due to what is current formed in conductors?