The Bohr radius, often denoted as "a₀," is a fundamental physical constant in quantum mechanics and atomic physics. It is named after the Danish physicist Niels Bohr, who made significant contributions to our understanding of atomic structure.
The Bohr radius represents the average distance between the nucleus and the electron in the lowest energy state (ground state) of a hydrogen atom, or a hydrogen-like ion with a single electron (e.g., helium ion with only one electron remaining). It is a key parameter in the Bohr model of the hydrogen atom.
The Bohr radius is defined as:
a₀ = (4πε₀ħ²) / (me²),
where:
When you calculate the Bohr radius using these constants, you get a value of approximately 5.29177210903 x 10⁻¹¹ meters, or about 0.5292 angstroms (Å).
The Bohr radius is a critical parameter in understanding the structure of atoms, particularly hydrogen-like atoms. It provides a basic scale for the size of atomic orbitals and helps in describing the energy levels of electrons in these atoms.
There isn't a widely accepted international standard for a "nautical league." The nautical mile (nmi) is the more common and internationally recognized unit of measurement for distances at sea. A nautical mile is approximately equal to one minute of latitude along a meridian, and it is used worldwide for maritime and aviation navigation.
In some regions, historical or localized variations of the league may have been used in the past, but these are not part of the modern international system of measurement. It's important to note that such variations can differ by country and even within different historical periods.
For precise and internationally recognized measurements in maritime and aviation contexts, the nautical mile is the preferred unit of distance. One nautical mile is equal to approximately 1.852 kilometers or 1.15078 statute miles (land miles).