Tera-

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This article is about the SI prefix. For other uses, see Tera.

Tera is a unit prefix in the metric system denoting multiplication by one trillion, or 1012 or 1000000000000 (one trillion short scale; one billion long scale). It has the symbol T. Tera is derived from the Greek word τέρας teras, meaning "monster";[1] also it resembles tetra, meaning "four" but with the middle letter removed as it is the fourth power of 1000.[2] The unit prefix was confirmed for use in the International System of Units (SI) in 1960.

Examples of its use:

  • terahertz radiation: electromagnetic waves within the band of frequencies from 0.3 to 3 THz. Visible light is around 500 THz.
  • terabit and terabyte, units used in data storage. Tebi-, or 240 is the closest binary prefix being ≈9.95% greater than 1012.
  • teragram: equal to 109 kg. The Great Pyramid of Giza has a mass of about 6 Tg.
  • terasecond: approximately 31,558 years
  • teralitre: equal to 109 m3. Lake Zurich contains about 4 TL of water.
  • terawatt: used to measure total human energy consumption. In 2010 it was 16 TW (TJ/s).
  • terametre (= 1,000,000,000 km): Light travels 1.079 Tm in one hour.
SI prefixes
  • v
  • t
Prefix Base 10 Decimal English word Adoption[nb 1] Etymology
Name Symbol Short scale Long scale Language Derived word
yotta Y  1024 1000000000000000000000000  septillion  quadrillion 1991 Greek eight[nb 2]
zetta Z  1021 1000000000000000000000  sextillion  trilliard 1991 Latin seven[nb 2]
exa E  1018 1000000000000000000  quintillion  trillion 1975 Greek six
peta P  1015 1000000000000000  quadrillion  billiard 1975 Greek five[nb 2]
tera T  1012 1000000000000  trillion  billion 1960 Greek four[nb 2], monster
giga G  109 1000000000  billion  milliard 1960 Greek giant
mega M  106 1000000  million 1873 Greek great
kilo k  103 1000  thousand 1795 Greek thousand
hecto h  102 100  hundred 1795 Greek hundred
deca da  101 10  ten 1795 Greek ten
 100 1  one –
deci d  10−1 0.1  tenth 1795 Latin ten
centi c  10−2 0.01  hundredth 1795 Latin hundred
milli m  10−3 0.001  thousandth 1795 Latin thousand
micro μ  10−6 0.000001  millionth 1873 Greek small
nano n  10−9 0.000000001  billionth  milliardth 1960 Greek dwarf
pico p  10−12 0.000000000001  trillionth  billionth 1960 Spanish peak
femto f  10−15 0.000000000000001  quadrillionth  billiardth 1964 Danish fifteen, Fermi[nb 3]
atto a  10−18 0.000000000000000001  quintillionth  trillionth 1964 Danish eighteen
zepto z  10−21 0.000000000000000000001  sextillionth  trilliardth 1991 Latin seven[nb 2]
yocto y  10−24  0.000000000000000000000001  septillionth  quadrillionth 1991 Greek eight[nb 2]
  1. ^ Prefixes adopted before 1960 already existed before SI. The introduction of the CGS system was in 1873.
  2. ^ Jump up to: a b c d e f Part of the beginning of the prefix was modified from the word it was derived from, ex: "peta" (prefix) vs "penta" (derived word).
  3. ^ The fermi was introduced earlier with the same symbol "fm", in which then the "f" became a prefix. The Danish word is used since it is vaguely spelled similar to fermi.

See also[]

References[]

  1. ^ "SI prefixes and their etymologies". US Metric Association. Retrieved 2021-06-11.
  2. ^ C. Upward, G. Davidson, The History of English Spelling, Wiley-Blackwell (2011)
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