Instant · Precise · Universal
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To convert to meters: multiply by 2.8179403262 × 10⁻¹⁵.
re = e²/(4πε₀mec²) ≈ 2.8179 × 10⁻¹⁵ m, where e is electron charge and me is electron mass.
For example, 1 Electron Radius (Classical) (re) = 2.817940e-17 Hectometer (hm).
| Electron Radius (Classical) (re) | Hectometer (hm) |
|---|---|
| 0.1 | 2.817940e-18 |
| 0.5 | 1.408970e-17 |
| 1 | 2.817940e-17 |
| 2 | 5.635881e-17 |
| 5 | 1.408970e-16 |
| 10 | 2.817940e-16 |
| 25 | 7.044851e-16 |
| 50 | 1.408970e-15 |
| 100 | 2.817940e-15 |
| 500 | 1.408970e-14 |
| 1000 | 2.817940e-14 |
The classical electron radius is a theoretical length scale derived from the electron's charge and mass, approximately 2.818 × 10⁻¹⁵ meters.
re = e²/(4πε₀mec²) ≈ 2.8179 × 10⁻¹⁵ m, where e is electron charge and me is electron mass.
To convert to meters: multiply by 2.8179403262 × 10⁻¹⁵.
Used in calculating X-ray and gamma-ray scattering probabilities off electrons (Thomson and Compton scattering).
Despite its name, the electron is a point particle in quantum theory — the 'classical radius' is a theoretical construct, not the electron's actual size.
Assuming this is the actual physical size of the electron — quantum mechanics shows the electron has no measurable size.
Think of it as the scale at which classical electromagnetic self-energy equals the electron's mass-energy.
The hectometer is a unit of length equal to 100 meters, or one tenth of a kilometer.
1 hm = 100 m = 0.1 km = 10 dam. One square hectometer (hm²) equals one hectare.
To convert hm to meters: multiply by 100. To convert hm to km: divide by 10.
The hectare (1 hm²) is its most common derived application. Occasionally used for short road distances.
A 100-meter Olympic sprint is exactly 1 hectometer. The hectare = 1 hm² is far more famous than the hectometer itself.
Confusing hectometer with hectare — the hectometer is a unit of length, the hectare is a unit of area (1 hectare = 1 hm²).
A football field is roughly 1 hectometer long — use this as a mental benchmark for 100 meters.



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