Machines

Yes, It's magic. Ask your teacher.

I DON'T HAVE GOOD TEACHER LIKE URS MAYBE U ASK UR TEACHER AND TELL ME....... :-)

I'd "stick" to magnets, if I were you.

Are you taking a class in electrics?

To clarify, electrons only flow "when the conductor revolves in the magnetic field" and there is an external circuit for them to flow in.

Without the external circuit, a voltage potential is developed, but no current (i.e., electrons) flows.

With an external circuit, electrons forced out of the conductor in the magnetic field are replaced with the electrons forced out of the conductor in the external circuit.

Barring any discussions of quantum theory, the same electrons just keep going around and around in the circuit--moved by the energy provided by the relative movement of the conductor and magnetic field.

just consider a dc generator ...............how the way electricity is produced

Ok. If the generator is running, but no external load is connected, no electrons will flow. There will be a voltage potential, but no current (electron) flow.

when there is potential difference there must be flow of electrons ??? emf is the electrical effort to move the electrons in a particular direction na???

NO. This is not correct. Many times there is no net electron flow but an emf (voltage) exists. Consider taking two batteries in parallel with identical output voltages. One has a completed circuit path but because the the voltages generated by batteries are the given value of identical there is no current flow.

Perhaps this may help.Two states......Infinite voltage and no current;Open circuit Infinite current no voltage; Short circuit In electrical circuits, we are dealing with steady state conditions.

malar,

You are asking some very good fundamental questions here. Your questions tell me that you will be a good candidate for an electrical engineering program. I hope that you consider getting formally educated. Now onto your specific question.

To answer your question I must start with some Chemistry. I presume that you know that atoms have a positively charged nucleus and a negatively charged cloud of electrons around the nucleus. The number of protons in the nucleus match the number of electrons in the cloud to make a neutrally charged atom. The metals (conductors) want to share their outer shell electrons but complete removal of an electron makes an ion that quickly grabs back that electron. But when a completed loop of conductors exist (a closed circuit) the electron that can be moved out gets replaced by the electron that gets moved in. This way at voltages much to small to cause ionization an electric current happens.

Maybe it just comes down to the difference between energy and matter?

Dear Malar, As a recent student of electrical studies myself, I have had similar questions. Kirchhoff's Current Law states; the sum of all the currents in a circuit is zero. This fundamental law results from the conservation of charge. It applies to a junction or node in a circuit -- a point in the circuit where charge has several possible paths to travel. Once charge has entered into the node, it has no place to go except to leave (this is known as conservation of charge). The total charge flowing into a node must be the same as the the total charge (carrier) flowing out of the node. Then, the sum of all the currents is zero. Magnetic fields store/return the energy of the charge (not the charge).