Arbitrary unit

In science and technology, an arbitrary unit (abbreviated arb.

[2] The unit only serves to compare multiple measurements performed in similar environment, since the ratio between the measurement and the reference is a consistent and dimensionless quantity independent of what actual units are used.

Units of such kind are commonly used in fields such as physiology to indicate substance concentration, and spectroscopy to express spectral intensity.

[2] Abbreviations for "arbitrary unit" include: arb.

[2] The decision forbids using factors or denominators in conjunction with p.d.u.

In the vertical axis of this graph, arbitrary unit is used to express approximate trend in the current–voltage characteristic of a generic field-effect transistor . It allows to downplay the current 's dependence on an individual device (the current depends on its size and other factors). Contrary, the voltage scale relies on electronic properties of the semiconductor , hence volts are given.