Ohm's law

Ohm’s law, first postulated in 1827, states that within any closed circuit there is a direct relationship between the pressure applied and the energy produced. When the temperature gauge on an electric kitchen stove is turned up, for example, the stove’s surface will get hotter. Ohm’s law applies specifically to electrical currents in that the amount of electrical current produced is directly related to the amount of pressure, or voltage, applied. In other words, the amount of electrical current that passes through and between metal conductors (a circuit) is directly proportional to the electrical force, or voltage, introduced into the circuit, and the greater the voltage, the stronger the current.

Background

Energy in any form has to be pushed through a closed system in order for it to move the elements within that system consistently. If someone wants to turn down an electric fry pan to its lowest degree of heat, for example, he or she must turn the controls down in order to lower the temperature, which introduces resistance in the circuit to moderate the electrical flow and, in turn, decreases the surface temperature of the pan. Ohm’s law relates the pulse that animates the motion and the velocity with which it moves within a closed system circuit and the movement between the two ends of that transaction. To increase the movement outward, increased pressure must be applied to one end. If the system’s temperature remains the same, the current is equal to the voltage applied divided by the distance it must cover. For instance, if the voltage is doubled between two ends of a wire, the current will double as well.

At the height of the Enlightenment era, Georg Simon Ohm (1789–1854), German instructor of mathematics at the Jesuit Gymnasium of Cologne, was part of a new breed of young scientists who sought to not only observe and, in turn, transcribe natural events but to also investigate and question the accepted logic of the time. What Ohm discovered about electrical currents through his empirical research was that given that electricity flows (which had been established over fifty years earlier), there is no perfect medium for its transference and that resistance is always an element of the flow. The result of more than two years’ worth of laboratory investigation and calculations revealed a direct relationship between the movement of charged particles (later identified as electrons) and the distance they must cross. In short, there exists a direct relationship between voltage and current.

Ohm’s law was formulated specifically to account for the particular movement and logic of an electrical current. Building on the theoretical work of research scientists in the late eighteenth century who were attempting to account for the logic of electricity (how electrons created a circuit and how they moved between points despite differing distances and resistances), Ohm understood there had to be a direct relationship between the voltage applied and the current produced. Ohm’s Law governs specifically the movement of free electrons between two points, which in turn creates a circuit. Like water in a garden hose, electrons must be directed in order to be useful. Electric currents are made up of electrons that must be continuously moved and directed between two points. Electrons tend to travel in random movements. The application of a specific volume of force or resistance will direct the electrons to move in a predetermined path or current that can then be controlled through the artificial introduction of resistors. Those resistors will, for example, create different heat settings on stovetops or different airflow volumes in hair dryers. Without resistance, full-force voltage from a wall socket would burn out most appliances, light fixtures, and electronic equipment. The unit of measure for this resistance is called the ohm. If the voltage is divided by the current in the wire, the resistance can be determined.

Overview

Ohm’s law uses the formula V = IR to find the correlation among voltage, current, and resistance. V (some disciplines use an E) represents the voltage (or energy) required to make the electrons move in concert and in a single direction between points, measured in volts. I is the current strength or pressure that is necessary to make the electrons move, measured in amperes, and R is the resistance of free-floating electrons, measured in ohms.

Some electrons are naturally resistant to being directed toward a point and need pressure to be moved. Other electrons require that the necessary resistance be artificially introduced into an electrical system in order to moderate and/or control the voltage power. Examples include adjusting temperature control dial on an oven to control the amount of heat produced or operating a dimmer switch to adjust the level of light.

Ohm’s law is among the most widely used formulas of the modern era and is seen as an entry-level equation for any electrical engineer. The formula governs, with some exceptions, the work of virtually all electrical circuits. By defining the relationship between voltage, current, and resistance, Ohm’s law helps explain and define the efficiency of virtually any circuit from batteries to computers to elevator lift systems to the electrical circuits regulating space shuttles and missile launching systems.

Bibliography

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