Now this might be a very stupid question for many readers, but I am getting really confused.
I was reading about electricity and current, and I read this:
Suppose we connect a wire to the ends of a battery, and a bulb in the circuit, current flows and lights up the bulb. The battery is responsible for doing work on the positive charges to move them from negative terminal to positive terminal, that is moving against the field. Now, these energised positive charges move through the external circuit, and within the circuit they give some of their energy to light the bulb. I understood this very well.
Now, reading further, it was written that "Electrons are actually responsible for current flow". It was written that there is concentration of energised negative charges on the negative terminal, and these electrons then move through the external circuit from negative to positive terminal. This is really confusing.
So my question: What actually flows? The negative charge or the
positive charge?
Further reading, I also read that in semi-conductors, fluorescent light bulbs etc., both charges move through the circuit.
Now, one more doubt: If both charges move through the circuit in this
case, shouldn't the charges stop in the middle of the wire, because
opposite charges will attract each other, hence stopping their
movement?
Best Answer
In a copper wire there are copper ions with 28 bound electrons orbiting the nucleus. Approximately one electron per copper atom is free to roam throughout the metal and these electrons are called unbound or free electrons ans are responsible for electrical (and heat) conduction in copper. The positive copper ions are bound together and only vibrate about a fixed position.
Long ago it was not know how copper conducted electricity and it was arbitrarily decided that the electric current was due to a flow of positive charges and the direction in which they flow is what is now called the (conventional) current direction.
Some people have tried to overturn this convention and designate the direction of current flow as that taken by the free electrons. Such attempts have failed because of inertia (almost all textbooks have the current flow as though it was positive charges which are responsible for the conduction process) and the fact that there are situations when the mobile charge carriers are positive. For example in water is a conductor because of mobile hydrogen ions which are positive and hydroxyl ions which are negative.