An electric circuit is a battery connected to metal wires of various lengths and thicknesses in various patterns. To understand electric circuits, we need to use our ideas of metallic bonding and what happens inside a battery.

Metallic bonding

We can consider a piece of metal as a collection of ‘atom cores’ surrounded by delocalised outer electrons. One way to represent this is as below:

Another way is to use dots for the delocalised electrons:

The delocalised electrons are moving randomly, from place to place. On the scale of a few atoms they will be different distances apart at any instance. However on the scale of a lump, due to the mutual repulsion between electrons, we can expect to find an even distribution. In other words, the concentration of delocalised electrons will be the same all over the lump. (In the same way that the concentration of air particles in a room is the same in all parts - ignoring the effect of gravity.)