The nautical mile in the United Kingdom, as in most countries, follows the international standard, which is approximately equal to 1.852 kilometers or 1.15078 statute miles (land miles). This international standard for the nautical mile is used for maritime and aviation navigation in the UK, as well as in many other countries around the world.
To provide some context, the nautical mile is based on the Earth's circumference and is defined as one minute of latitude along a meridian. It is commonly used in navigation because it provides a consistent and convenient way to measure distances at sea and in the air, where latitude is an essential factor. The use of the international nautical mile ensures compatibility and consistency in maritime and aviation operations across different regions and countries.
In the field of atomic and molecular physics, an "atomic unit of length" is a unit of measurement that is used to express distances at the atomic and molecular scale in a dimensionless way. It is part of a system of atomic units (a.u.) that simplifies calculations involving fundamental physical constants and properties of atoms and molecules.
The atomic unit of length (a.u. of length) is defined in terms of the Bohr radius (a₀), which is a fundamental constant in atomic physics. The Bohr radius is approximately 0.52917721067 angstroms (Å) or 5.2917721067 x 10^-11 meters (m).
In atomic units, the Bohr radius is set to exactly 1 a.u. of length. Therefore, when using atomic units, distances are expressed relative to the Bohr radius, and the value of 1 a.u. of length corresponds to the typical size scale of atomic and molecular structures.
The use of atomic units simplifies many quantum mechanical calculations and allows physicists and chemists to work with dimensionless quantities, making it easier to compare and analyze atomic and molecular properties.