DC Circuits: Ohm's Law

Ohm's Law is called such because of it's discoverer, Georg Simon Ohm (Wikipedia link). If you went to the Wiki page, you'll learn that he found out about some proportionality with the applied voltage and the resulting current.

where,
I is the resulting current
V is the voltage applied
R is the resistance of the circuit

The Ohm's law, mathematically, means that if there is neither voltage nor resistance in a circuit, neither is there current flowing in the circuit. However, even a wire has some resistance in which the value depends on what it's kind is - copper, aluminum, etc.

Calculating a circuit's voltage and/or resistance, we just need to do Algebra to the Ohm's Law.


Note that:
I is in Amperes,
V is in Volts, and
R is in Ohms

Note and Remember: Series elements have the same Current values, but they have different voltage values. Parallel elements have the same Voltage values, but they have different Current values.
SCPR for Series-Current, Parallel-Voltage.

This law also applies to Alternating Current circuits and not just to Direct Current circuits. Though, resistance in an AC circuit is different from the resistance in a DC one. AC's resistance is called Impedance and has a different meaning to it. See this to learn more about this topic.

From Ohm's Law come different techniques in calculating resistance through voltage divider or current divider, node voltages, branch currents, voltage drops across elements, etc. We will cover these specific topics in the coming days.