I understand that electrons are not created nor destroyed. In AC voltage the electrons are oscilating back and forth in material. But I cannot understand where do the electrons come from that are created by DC generator. Because by DC generator the electrons in the conductor flow only in one direction, logicaly they have to be somewhere lost and created. What Am I missing?
A DC generator acts like a pump that pushes electrons round the circuit. Electrons go out from the negative terminal of the generator and flow into the positive terminal forming a closed loop, nothing gets created nor destroyed.