Units of Measurement
SI Units
The table below shows the Units of Measurement also called SI Units.| Physical Quantity | Name of Unit | Abbreviation |
|---|---|---|
| Mass | Kilogram | kg |
| Length | Meter | m |
| Time | Second | ks or sec |
| Temperature | Kelvin | K |
| Amount of substance | Mole | mol |
| Electric current | Ampere | A or amp |
| Luminous intensity | Candela | cd |
Metric Prefixes
Base units are converted into units that are more common or convenient as illustrated in the table below.| Prefix | Abreviation | Meaning | Example |
|---|---|---|---|
| Peta | P | 1015 | 1 petabyte (PW) = 1 × 1015 bytes |
| Tera | T | 1012 | 1 terawatt (TW) = 1 × 1012 watts |
| Giga | G | 109 | 1 gigajoule (GJ) = 1 × 109 joules |
| Mega | M | 106 | 1 megabyte (MB) = 1 × 106 bytes |
| Kilo | k | 103 | 1 kilogram (kg) = 1 × 103 grams |
| Deci | d | 10− 1 | 1 decimeter(dm) = 1 × 10− 1 meter |
| Centi | c | 10− 2 | 1 centimeter(cm) = 1 × 10− 2 meter |
| Melli | m | 10− 3 | 1 milliwatt (mW) = 1 × 10− 3 watt |
| Micro | μ | 10− 6 | 1 microjoule(μJ) = 1 × 10− 6 joule |
| Nano | n | 10− 9 | 1 nanosecond(ns) = 1 × 10− 9 second |
| Pico | p | 10− 12 | 1 picowatt(pW) = 1 × 10− 12 watt |
| Femto | f | 10− 15 | 1 femtosecond(fs) = 1 × 10− 15 second |
| Atto | a | 10− 18 | 1 attowatt(aW) = 1 × 10− 18 watt |
| Zepto | d | 10− 21 | 1 zeptojoule(zJ) = 1 × 10− 21 joule |
Temperature Units Used in Science
- Celsius scale: based on the properties of water.
- Kelvin scale: the “absolute” temperature, which is the SI unit of temperature.
- The Kelvin unit has the same size as the Celsius unit, but the two scales have different zero points.
- 0 K is the lowest possible temperature ("absolute zero").
- This the point at which all thermal energy would have been drained from an object; so the temperature cannot get any lower.
- 0 K = − 273.15 °C, so K = °C + 273.15