What is Ohm’s Law?
Ohm's Law states that current through a conductor across two points is directly proportional to voltage, given a constant resistance. The law is named after the German physicist Georg Ohm whose experiments inspired its framework. Ohm's Law is represented by the equation I = V/R where I is the current in amperes, V is the voltage measured between the two points of the conductor, and R is the resistance defined in Ohms. The law states that the resistance remains a constant, independent of the current. Ohm's Law is used as a general principle for understanding conductivity of materials over a varying range of electrical currents. Materials can be defined as either ohmic, or non-ohmic, depending on whether they follow the rules of the law.
Applications of Ohm's Law
Ohm's Law is sometimes exemplified and denoted in a few variations. For example, Ohm's Law can be defined as either:
I = V/R
V = IR
R = V/I
The interchangeability of the definitions is sometimes displayed as a trifurcated triangle, with V on the top, and I and R denoted below. The interchangeable definition is displayed as:
It is common to see these various definitions in the process of circuit analysis. Circuit analysis is the voltages and currents through every component in a network. Each component can be defined as either ohmic, or non-ohmic.
Ohm's Law and Linear Approximations
Ohm's Law can be visualized using linear functions. If a component is truly ohmic, its resistance will not increase, regardless of any increase or decrease in voltage. In short, the ratio of V to I is constant, resulting in a straight line across a graph. If a component is non-ohmic, then the plotted line may curve, representing a non-constant ratio between the current and the voltage. The graphs below display the differences between ohmic, and non-ohmic components.
By Sbyrnes321 - Own work, CC0, https://commons.wikimedia.org/w/index.php?curid=17718257