International System of Units (SI)
SI Units are the formal terms, definitions, and symbols used in the metric system. SI units start from base units which are the axiomatic building blocks from which all other units, called derived units, are created.
Base units include standard measures for time (second), distance (meter), mass (kilogram), pressure (bar), and more. Derived units combine base units, for example velocity () is distance () over time (), or .
SI Unit Prefixes
| Prefix | Symbol | Value |
|---|---|---|
| tera | ||
| giga | ||
| mega | ||
| kilo | ||
| hecto | ||
| deca | ||
| deci | ||
| centi | ||
| milli | ||
| micro | ||
| nano |
SI Resources
Deeper Knowledge on International System of Units (SI)
Conductance and Siemens
The ability to conduct to current, measured in siemens
Bureau International des Poids et Mesures (BIPM)
Keepers of SI Units and UTC time scale
Charge and Coulombs
How force is exerted in electromagnetic field, measured in coulombs
Resistance and Ohms
Opposition to current, measured in ohms
Frequency and Hertz (Hz)
The number of times something happens per second
Scientific Notation
Expressions of very large and very small numbers in science and math
Engineering Notation
Expressions of very large and very small numbers for engineers
Current and Amperes
The flow of electricity, measured in amps
Voltage and Volts
Electrical potential energy, measured in volts
Watt's Law (Power Law)
A formula to define the relationship between power, voltage, and current (P=IV)
Broader Topics Related to International System of Units (SI)
Science
The most rigorous system of epistemology
Engineering
Apply science to create technology