Flow of electrons through a metal wire
The charge flows from one point to other in a conductor.
If we apply a type of force (called electromotive force) to the metal wire, the electrons will “flow” through the wire as is shown in the picture. The electrons will jump from one nucleus to the next along the path of the wire.
Think of a “plane” through the wire and we can see that a certain number of electrons pass through the plane during each unit of time. This is known as "electrical current".
Mathematically, we can write this as
I = charge/time or I = q/t,
where 'I' is the current, 'q' is charge, and 't' is the time. Attach the copper wire to a small bulb. Connect the bulb and the other end of the copper wire to two terminals of a small battery through a key (or a switch).
As you connect the key, what do you observe?
The bulb starts glowing! Remove the key and the bulb stops glowing.
Take another battery and connect to the earlier. You will observe that the glow of the bulb is stronger. From the knowledge gained in the earlier lessons, we know that:
- charges are attracted to opposite charges with a force given by Coulomb’s law.
- charges move so as to neutralize any excess charges.
Now you will immediately guess that the bulb is glowing because of flow of electrons through the copper wire. When two batteries are connected, the bulb glows more strongly because there is more flow of electrons.