I have been thinking of the nature of the electric current , or the motion of electrons in a copper cable of a closed DC circuit. Recently I learned the speed of electron is very slow in the copper cable and in a AC circuit the FREE ELECTRONS are in fact moving back and forth. But in a DC circuit, if enough long time is given, will a specific electron finally move though the cable and power source and come to the point it started motion? That is my question. Thanks for enlighten me.