A simple electric circuit is represented by the following line diagram
A voltage source #v# connected through conducting wires to a resistance #R#.
As shown, the direction of current #i# is from #+ve# terminal of the voltage source towards the #-ve# terminal.
We know that flow of electric charge in a closed circuit constitutes flow of current.
- This charge is often carried by moving electrons in a wire.
- It is carried by ions in an electrolyte.
- Both ions and electrons carry charge in case of plasma.
Thumb rule: Unlike charges attract each other and like repel.
As per convention#"^&#we need to remember that, as shown in the figure below, the flow of electrons is towards #+ve# terminal.
Electrons are #-vely# charged particles and therefore are attracted towards the terminal which has opposite polarity. This direction is the opposite to the direction of conventional current flow in an electrical circuit.
Positive charge carriers flow toward #-ve# terminal. This is the direction of the conventional current.
If it is a DC battery, it is shown in the circuit as
#"^&# When we say historical convention we are referring to the definition which existed before the discovery of electron, and application of electronic theory of matter to explain/describe the physical phenomena.