unipolaari

Unipolaari is a term with multiple meanings depending on the context. In electronics, a unipolar transistor is a type of field-effect transistor that relies on a single charge carrier type, either electrons or holes, for conduction. This is in contrast to bipolar transistors, which utilize both electrons and holes. Unipolar transistors are known for their high input impedance and are often used in amplifier and switching circuits.

In politics and international relations, a unipolaari system describes a distribution of power where one state holds the overwhelming majority of global power, influence, and military strength. This dominant state is often referred to as a superpower. Such a system implies a lack of significant rivals or competing centers of power. Historically, periods of unipolarity have been relatively short-lived.

The term can also appear in psychology, particularly in discussions of mood disorders. Unipolar depression, for instance, refers to a condition characterized by episodes of depression without the occurrence of manic or hypomanic episodes. This distinguishes it from bipolar disorder, which involves alternating periods of depression and mania or hypomania. The focus in unipolar depression is on the depressive state itself.