Ohms law is one of the most important concepts in electronics. Ohms law gives relationship between current, voltage, and resistance.

Ohms law:

"The amount of current flowing in a circuit is directly proportional to the electromotive forces impressed on the circuit and inversely proportional to the total resistance of the circuit."

According to the Ohms law, voltage equals current times resistance which is expressed in the following equation:
E=IR
where E = voltage, I = current, and R = resistance