Ohm's Law and Electrical Circuits

History of Georg Simon Ohm
Ohm's Law Diagram


Ohm's Law formulates the theory behind electrical circuits. It relates how voltage, current and resistance work together. For example, see the diagram below:

The force motivating electrons to "flow" in a circuit is called voltage. Voltage is a specific measure of potential energy that is always relative between two points. When we speak of a certain amount of voltage being present in a circuit, we are referring to the measurement of how much potential energy exists to move electrons from one particular point in that circuit to another particular point. Without reference to two particular points, the term "voltage" has no meaning.

Free electrons tend to move through conductors with some degree of friction, or opposition to motion. This opposition to motion is more properly called resistance. The amount of current in a circuit depends on the amount of voltage available to motivate the electrons, and also the amount of resistance in the circuit to oppose electron flow. The quantities of voltage and resistance are often stated as being "between" or "across" two points in a circuit.

In the example below, the light bulb acts as the "R", the battery acts as the "V" and the flow of electrons between the two is the "I":

For more about circuit theory click here or for more detailed information about resistance click here.

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