See the above figure.Water is being circulated in a closed rectangular tube by means of a motor.Its a beautiful analogue of DC circuit.In DC circuits battery plays the role of pump.Here you can notice that there is no net loss or gain in any particular segment of the loop.
But situation is different in the case of power supplied in our houses.Thats AC not DC.In AC electrons just drift back and forth in any segment of wire and this process is controlled by supplied voltage and frequency.
Post edited by: niraj001, at: 2008/03/09 07:18