Back تور (وحدة) Arabic Torr Catalan Torr Czech Torr German Torr Spanish Torr Basque تور (یکا) Persian Torri Finnish Torr French Torr Irish
| torr | |
|---|---|
| Unit of | pressure |
| Symbol | Torr |
| Named after | Evangelista Torricelli |
| Definition | 1/760 atm |
| Conversions | |
| 1 Torr in ... | ... is equal to ... |
| SI derived units | 133.3224 Pa |
| British Gravitational System | 0.01933677 psi |
The torr (symbol: Torr) is a unit of pressure based on an absolute scale, defined as exactly 1/760 of a standard atmosphere (101325 Pa). Thus one torr is exactly 101325/760 pascals (≈ 133.32 Pa).
Historically, one torr was intended to be the same as one "millimeter of mercury", but subsequent redefinitions of the two units made them slightly different (by less than 0.000015%). The torr is not part of the International System of Units (SI). Even so, it is often combined with the metric prefix milli to name one millitorr (mTorr) or 0.001 Torr.
The unit was named after Evangelista Torricelli, an Italian physicist and mathematician who discovered the principle of the barometer in 1644.[1]
- ^ Devices similar to the modern barometer, using water instead of mercury, were studied by a number of scientists in the early 1640s (see History of the Barometer). Torricelli's explanation of the principle of the barometer appears in a letter to Michelangelo Ricci dated 11 June 1644.