# What is the basic unit of length

## General information and resources

The physicist uses physical quantities to describe the properties (e.g. length) and states (e.g. temperature) of objects. You don't know all the physical quantities from your lessons, but you should already know a number of them: e.g. length, area, volume, time, current, voltage, charge and resistance. These quantities not only play an important role in physics but in many other areas. The adjacent illustration (source: physical-technical federal institute) gives you an impression of which parameters can play a role in the examination of a person.

Letters (written in italics) are used as an "abbreviation" for a physical quantity.

Example: The physical quantity "length" is usually symbolized with a \ (l \). For their precise specification you need a measure and a unit of measure.

 l = 5,0 m symbol Measure Unit of measurement

#### Basic sizes

In mathematics, the whole structure of laws is based on the so-called fundamental laws (axioms). Doctrines are then derived from them and finally new doctrines are developed from the doctrines.

In the size system of physics, the so-called base sizes correspond to the fundamental theorems. In 1960, a set of such basic sizes was agreed worldwide, the Système International d’Unités, in short SI system. A measurement specification must be specified for these basic quantities, which the unit, the equality and the Multiplicity this size defines. In the following, this is explained using two basic sizes that you already know.

#### Basic size length

unit

The unit of length is the meter. It was set (earlier) as the length of a prototype. Note: The unit of length has recently been determined differently.