fermi | 1 fm | 2 fm | 3 fm | 4 fm | 5 fm | 6 fm | 7 fm | 8 fm | 9 fm | 10 fm | 11 fm | 12 fm | 13 fm | 14 fm | 15 fm | 16 fm | 17 fm | 18 fm | 19 fm | 20 fm | 21 fm | 22 fm | 23 fm | 24 fm | 25 fm | 26 fm | 27 fm | 28 fm | 29 fm | 30 fm | 31 fm | 32 fm | 33 fm | 34 fm | 35 fm | 36 fm | 37 fm | 38 fm | 39 fm | 40 fm | 41 fm | 42 fm | 43 fm | 44 fm | 45 fm | 46 fm | 47 fm | 48 fm | 49 fm | 50 fm | 51 fm | 52 fm | 53 fm | 54 fm | 55 fm | 56 fm | 57 fm | 58 fm | 59 fm | 60 fm | 61 fm | 62 fm | 63 fm | 64 fm | 65 fm | 66 fm | 67 fm | 68 fm | 69 fm | 70 fm | 71 fm | 72 fm | 73 fm | 74 fm | 75 fm | 76 fm | 77 fm | 78 fm | 79 fm | 80 fm | 81 fm | 82 fm | 83 fm | 84 fm | 85 fm | 86 fm | 87 fm | 88 fm | 89 fm | 90 fm | 91 fm | 92 fm | 93 fm | 94 fm | 95 fm | 96 fm | 97 fm | 98 fm | 99 fm | 100 fm |
spat | 1.0 × 10-27 S | 2.0 × 10-27 S | 3.0 × 10-27 S | 4.0 × 10-27 S | 5.0 × 10-27 S | 6.0 × 10-27 S | 7.0 × 10-27 S | 8.0 × 10-27 S | 9.0 × 10-27 S | 1.0 × 10-26 S | 1.1 × 10-26 S | 1.2 × 10-26 S | 1.3 × 10-26 S | 1.4 × 10-26 S | 1.5 × 10-26 S | 1.6 × 10-26 S | 1.7 × 10-26 S | 1.8 × 10-26 S | 1.9 × 10-26 S | 2.0 × 10-26 S | 2.1 × 10-26 S | 2.2 × 10-26 S | 2.3 × 10-26 S | 2.4 × 10-26 S | 2.5 × 10-26 S | 2.6 × 10-26 S | 2.7 × 10-26 S | 2.8 × 10-26 S | 2.9 × 10-26 S | 3.0 × 10-26 S | 3.1 × 10-26 S | 3.2 × 10-26 S | 3.3 × 10-26 S | 3.4 × 10-26 S | 3.5 × 10-26 S | 3.6 × 10-26 S | 3.7 × 10-26 S | 3.8 × 10-26 S | 3.9 × 10-26 S | 4.0 × 10-26 S | 4.1 × 10-26 S | 4.2 × 10-26 S | 4.3 × 10-26 S | 4.4 × 10-26 S | 4.5 × 10-26 S | 4.6 × 10-26 S | 4.7 × 10-26 S | 4.8 × 10-26 S | 4.9 × 10-26 S | 5.0 × 10-26 S | 5.1 × 10-26 S | 5.2 × 10-26 S | 5.3 × 10-26 S | 5.4 × 10-26 S | 5.5 × 10-26 S | 5.6 × 10-26 S | 5.7 × 10-26 S | 5.8 × 10-26 S | 5.9 × 10-26 S | 6.0 × 10-26 S | 6.1 × 10-26 S | 6.2 × 10-26 S | 6.3 × 10-26 S | 6.4 × 10-26 S | 6.5 × 10-26 S | 6.6 × 10-26 S | 6.7 × 10-26 S | 6.8 × 10-26 S | 6.9 × 10-26 S | 7.0 × 10-26 S | 7.1 × 10-26 S | 7.2 × 10-26 S | 7.3 × 10-26 S | 7.4 × 10-26 S | 7.5 × 10-26 S | 7.6 × 10-26 S | 7.7 × 10-26 S | 7.8 × 10-26 S | 7.9 × 10-26 S | 8.0 × 10-26 S | 8.1 × 10-26 S | 8.2 × 10-26 S | 8.3 × 10-26 S | 8.4 × 10-26 S | 8.5 × 10-26 S | 8.6 × 10-26 S | 8.7 × 10-26 S | 8.8 × 10-26 S | 8.9 × 10-26 S | 9.0 × 10-26 S | 9.1 × 10-26 S | 9.2 × 10-26 S | 9.3 × 10-26 S | 9.4 × 10-26 S | 9.5 × 10-26 S | 9.6 × 10-26 S | 9.7 × 10-26 S | 9.8 × 10-26 S | 9.9 × 10-26 S | 1.0 × 10-25 S |
The femtometre (American spelling femtometer, symbol fm derived from the Danish and Norwegian word femten, "fifteen"+Ancient Greek: μέτρον, metrοn, "unit of measurement") is an SI unit of length equal to 10−15 metres, which means a quadrillionth of one. This distance can also be called a fermi and was so named in honour of physicist Enrico Fermi, as it is a typical length-scale of nuclear physics.
Name of unit | Symbol | Definition | Relation to SI units | Unit System |
---|---|---|---|---|
fermi | fm | ≡ 1×10−15 m | ≡ 1×10−15 m | Metric system Non-SI |
fermi | spats | fermi | spats |
---|---|---|---|
1 | ≡ 1.0E-27 | 4 | ≡ 4.0E-27 |
1.5 | ≡ 1.5E-27 | 4.5 | ≡ 4.5E-27 |
2 | ≡ 2.0E-27 | 5 | ≡ 5.0E-27 |
2.5 | ≡ 2.5E-27 | 5.5 | ≡ 5.5E-27 |
3 | ≡ 3.0E-27 | 6 | ≡ 6.0E-27 |
The spat (symbol S) is also an obsolete unit of distance used in astronomy. It is equal to 1000000000 kilometres (1 Tm or 1012 m). It is about 6.6846 astronomical units (AU), 1.057×10−4 light-years or3.240×10−5 parsecs.
Name of unit | Symbol | Definition | Relation to SI units | Unit System |
---|---|---|---|---|
spat | S | ≡ 1×1012 m | ≡ 1×1012 m | Science - Astronomy (Length) |
spats | fermi | spats | fermi |
---|---|---|---|
1 | ≡ 1.0E+27 | 4 | ≡ 4.0E+27 |
1.5 | ≡ 1.5E+27 | 4.5 | ≡ 4.5E+27 |
2 | ≡ 2.0E+27 | 5 | ≡ 5.0E+27 |
2.5 | ≡ 2.5E+27 | 5.5 | ≡ 5.5E+27 |
3 | ≡ 3.0E+27 | 6 | ≡ 6.0E+27 |
fermi | spats |
---|---|
1 | ≡ 1.0 × 10-27 |
1.0 × 1027 | ≡ 1 |
Symbol | Definition |
---|---|
≡ | exactly equal |
≈ | approximately equal to |
= | equal to |
digits | indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …) |