Ohm law is defined as the voltage is equal to the current product by the resistance.
V = I * R
where:
V = voltage [volt]
I = current [amp]
R = resistance [ohm]
Therefore for a current to exist there must be a voltage and elements that exert resistance to the passage of electrons from one point to another.
There must be a closed loop between the connection points of the source, so that the current can flow freely. Any opening of the circuit will interrupt the current flow.
