Convert Ell (ell) to Bohr Radius (a₀) instantly.
About these units
Ell (ell)
The ell is a traditional European unit of length, varying between 45–70 cm depending on the region. It originated from the forearm or arm length and became standardized in many countries for measuring cloth and textiles. In commerce, the ell simplified transactions, allowing merchants to describe fabric lengths efficiently. In tailoring, it offered a consistent basis for cutting and patterning clothing. The unit was essential in guild systems, where precision and repeatability in textile production were critical. While largely obsolete today due to the metric system, the ell remains significant for historians, textile scholars, and anyone studying pre-modern European commerce and craft practices.
Bohr Radius (a₀)
The Bohr radius, equal to approximately 5.29177 × 10⁻¹¹ meters, is the most probable distance between the electron and nucleus in the ground state of hydrogen according to the Bohr model. While modern quantum mechanics has evolved far beyond the Bohr model, the radius remains a remarkably accurate approximation for average atomic dimensions. The Bohr radius acts as a natural "yardstick" for the size of atoms and is frequently used in atomic physics and quantum chemistry. Many atomic properties — orbital sizes, electron probability distributions, and energy levels — are conveniently expressed in multiples of the Bohr radius. Because it reflects fundamental constants, including Planck's constant and the electron charge, the Bohr radius also appears in theoretical analyses of physical systems and helps unify atomic physics concepts across different contexts.