ühepooluseline

ühepooluseline is an Estonian term that translates to "unipolar" in English. It is most commonly used in a scientific context, particularly in physics and electronics.

In physics, a unipolar device or system refers to one that operates based on the movement of charge carriers of only one sign. For example, in a semiconductor device, if conduction is primarily due to electrons, it is considered n-type and potentially exhibits unipolar behavior. Conversely, if conduction is primarily due to holes, it is p-type and also potentially unipolar. This contrasts with bipolar devices where both electrons and holes contribute significantly to current flow.

In electronics, a unipolar transistor is a type of field-effect transistor (FET) where the current flows through only one type of charge carrier. Examples include MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) and JFETs (Junction Field-Effect Transistors). Their operation relies on controlling the conductivity of a semiconductor channel through an electric field, without the injection of minority carriers.

The term can also be used more generally to describe something that has a single pole or a single dominant characteristic. For instance, in political science, a "unipolar world" refers to a global system where one superpower holds overwhelming political, economic, and military dominance. However, its primary and most precise usage remains within the scientific and technical fields.