Ohms Law Calculator
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Ohm's law
About Ohm's Law
This is a simple Ohm’s law/Joule’s first law calculator.
Ohm’s law
Ohm’s law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality, the resistance,[1] one arrives at the usual mathematical equation that describes this relationship:[2]
where I is the current through the conductor in units of amperes, V is the voltage measured across the conductor in units of volts, and R is the resistance of the conductor in units of ohms. More specifically, Ohm’s law states that the R in this relation is constant, independent of the current.[3]Ohm’s law is an empirical relation which accurately describes the conductivity of the vast majority of electrically conductive materials over many orders of magnitude of current. However some materials do not obey Ohm’s law, these are called non-ohmic.
The law was named after the German physicist Georg Ohm, who, in a treatise published in 1827, described measurements of applied voltage and current through simple electrical circuits containing various lengths of wire. Ohm explained his experimental results by a slightly more complex equation than the modern form above (see History).
In physics, the term Ohm’s law is also used to refer to various generalizations of the law; for example the vector form of the law used in electromagnetics and material science:
where J is the current density at a given location in a resistive material, E is the electric field at that location, and σ (sigma) is a material-dependent parameter called the conductivity. This reformulation of Ohm’s law is due to Gustav Kirchhoff.[4]
Joule heating
Joule heating, also known as Ohmic heating and resistive heating, is the process by which the passage of an electric current through a conductor produces heat.
Joule’s first law, also known as the Joule–Lenz law,[1] states that the power of heating generated by an electrical conductor is proportional to the product of its resistance and the square of the current:
Joule heating affects the whole electric conductor, unlike the Peltier effect which transfers heat from one electrical junction to another.
