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Femto (f) Unit Definition
Femto is a SI unit prefix in the metric system denoting a factor of 10-15. It is derived from the Danish word femten, meaning fifteen. It is represented by the prefix femto or the symbol f.
Overview
The femtometer shares the unit symbol (fm) with the older non-SI unit fermi, to which it is equivalent. The fermi, named in honor of Enrico Fermi, is often encountered in nuclear physics.
Examples
The HIV-1 virus has the mass of about 1 x 10−15 grams (g) or 1 femtograms (fg).
A proton has a diameter of about 1.66 femtometers (fm).
SI Prefixes
Here is a table of the SI prefixes and some of their properties:
Name & Symbol |
Base 10 |
Decimal |
English Word |
Adoption |
|
Short Scale |
Long Scale |
||||
Quetta (Q) | 1030 |
1,000,000,000,000,000,000,000,000,000,000 |
Nonillion |
Quintillion |
2022 |
Ronna (R) | 1027 |
1,000,000,000,000,000,000,000,000,000 |
Octillion |
2022 |
|
Yotta (Y) | 1024 |
1,000,000,000,000,000,000,000,000 |
Septillion |
Quadrillion |
1991 |
Zetta (Z) | 1021 |
1,000,000,000,000,000,000,000 |
Sextillion |
Trilliard |
1991 |
Exa (E) | 1018 |
1,000,000,000,000,000,000 |
Quintillion |
Trillion |
1975 |
Peta (P) | 1015 |
1,000,000,000,000,000 |
Quadrillion |
Billiard |
1975 |
Tera (T) | 1012 |
1,000,000,000,000 |
Trillion |
Billion |
1960 |
Giga (G) | 109 |
1,000,000,000 |
Billion |
Milliard |
1960 |
Mega (M) | 106 |
1,000,000 |
Million |
1873 |
|
Kilo (k) | 103 |
1,000 |
Thousand |
1795 |
|
Hecto (h) | 102 |
100 |
Hundred |
1795 |
|
Deca (da) | 101 |
10 |
Ten |
1795 |
|
One (1) | 100 |
1 |
One |
- |
|
Deci (d) | 10-1 |
0.1 |
Tenth |
1795 |
|
Centi (c) | 10-2 |
0.01 |
Hundredth |
1795 |
|
Milli (m) | 10-3 |
0.001 |
Thousandth |
1795 |
|
Micro (µ) | 10-6 |
0.000001 |
Millionth |
1873 |
|
Nano (n) | 10-9 |
0.000000001 |
Billionth |
Milliardth |
1960 |
Pico (p) | 10-12 |
0.000000000001 |
Trillionth |
Billionth |
1960 |
Femto (f) | 10-15 |
0.000000000000001 |
Quadrillionth |
Billiardth |
1964 |
Atto (a) | 10-18 |
0.000000000000000001 |
Quintillionth |
Trillionth |
1964 |
Zepto (z) | 10-21 |
0.000000000000000000001 |
Sextillionth |
Trilliardth |
1991 |
Yocto (y) | 10-24 |
0.000000000000000000000001 |
Septillionth |
Quadrillionth |
1991 |
Ronto (r) | 10-27 |
0.000000000000000000000000001 |
Octillionth |
2022 |
|
Quecto (q) | 10-30 |
0.000000000000000000000000000001 |
Nonillionth |
Quintillionth |
2022 |
Other Prefix Unit Definitions
- Atto (a)
- Centi (c)
- Deca (da)
- Deci (d)
- Deka (da)
- Exa (E)
- Exbi (Ei)
- Femto (f)
- Gibi (Gi)
- Giga (G)
- Hecto (h)
- Kibi (Ki)
- Kilo (k)
- Mebi (Mi)
- Mega (M)
- Micro (µ)
- Milli (m)
- Nano (n)
- One (1)
- Pebi (Pi)
- Peta (P)
- Pico (p)
- Qubi (Qi)
- Quecto (q)
- Quetta (Q)
- Robi (Ri)
- Ronna (R)
- Ronto (r)
- Tebi (Ti)
- Tera (T)
- Yobi (Yi)
- Yocto (y)
- Yotta (Y)
- Zebi (Zi)
- Zepto (z)
- Zetta (Z)
Convert to Another Prefix Unit
Related Definitions
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Sources
“Femto-.” Wikipedia, Wikimedia Foundation, 12 Mar. 2020, en.wikipedia.org/wiki/Femto-.