Electrons have potential energy and are negatively charged. They move freely from a point of high energy level to a point of low energy level. There is a driving influence to cause the continuous flow of electrons. The driving influence is termed the electromotive force, hereafter called the EMF. As the very name implies, there is a “motive” in the EMF (electro ‘motive’ force) source. But, it is not actually a ‘force’ since it has no dimension.
The electrons starting from the negative of the EMF flows in the external circuit and reaches the positive of the EMF. The electron is attracted towards the positive potential. The flow of electrons is the current. The conventional current flows in the opposite direction to that of electron flow i.e., the current flows in the external circuit from the positive source EMF, the external load, and to the negative of the source EMF. Within the EMF source, the conventional current flows from negative to positive of EMF.
Explaining Electromotive Force
More energy is now provided by the chemical reactions in the cell source to move the electrons from the positive of EMF to the negative of EMF in the internal circuit of the EMF source and helps to continue further rounds. This is a continuous process as long as the external circuit is closed and also as long as there exits energy in the EMF source. And the current flow is continuous. It may be noted that the current is the rate of flow of charge through the circuit. You will see later that the voltage measured across the terminals of the resistance is the potential difference.
The video given below shows the EMF source (lead-acid cell) and the direction of current flowing in it.
