measurement unit that is adopted by convention for a base quantity

Notes click to expand contents

NOTE 1 In each coherent system of units, there is only one base unit for each base quantity.

EXAMPLE In the SI, the metre is the base unit of length. In the CGS systems, the centimetre is the base unit of length.

NOTE 2 A base unit may also serve for a derived quantity of the same quantity dimension.

EXAMPLE Rainfall, when defined as areic volume (volume per area), has the metre as a coherent derived unit in the SI.

NOTE 3 For number of entities, the number one, symbol 1, can be regarded as a base unit in any system of units.

Contents

Contents

1 Quantities and units click to expand contents

2 Measurement click to expand contents

3 Devices for measurement click to expand contents

4 Properties of measuring devices click to expand contents

5 Measurement standards (Etalons) click to expand contents

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