virtamäärä

Virtamäärä is a Finnish term formed from virta (current, flow) and määrä (amount, quantity). It is a generic concept used in physics, engineering and everyday language to denote the magnitude of a flow or the amount passing a point per unit time. The precise meaning depends on the context, and virtamäärä is not a single fixed physical quantity in itself.

In electrical engineering and circuit theory, virtamäärä commonly refers to the electric current, denoted by I. This is the rate at which electric charge passes a given point and is measured in amperes (A). A fundamental relation is I = dQ/dt, where Q is the electric charge. The concept is central to Ohm’s law and circuit analysis.

In fluid dynamics and related fields, virtamäärä can also describe the flow rate of a fluid through a cross-section. Depending on context, this may refer to volumetric flow rate (for example, cubic meters per second, m^3/s) or, less commonly, mass flow rate. In Finnish technical usage, the term virtaama or tilavuusvirta is often preferred for the standard volumetric flow rate, but virtamäärä may appear as a general reference to the magnitude of the flow.

Measurement of virtamäärä varies by domain: current is measured with an ammeter; flow rate with a flow meter or similar instrument. Understanding the context is essential to interpret the term correctly, as virtamäärä bridges disciplines that quantify different kinds of flow.

See also: Ohm’s law; continuity equation; flow rate.