Ohm’s law is the foundation for all electronic circuit analysis. The law in words, states that the current in a circuit is directly porportional to the resistance in the circuit. The formula is E=I x R. This is the voltage in the circuit is equal to the current times the resistance. From this we also get I=E/R and R=E/I.
From these equations we can get a whole host of other equations as we need them such as P=I^2 x R and so on.
For instance if we have a 12 volt battery with a 100 ohm resistor the current in the circuit is .12 amps or 120 milliamps. The power consumption in this simple circuit is 1.44 watts. Although this is the most basic circuit, we still gain a great deal of knowledge from it using Ohm’s law.