Light Year
A light year is a unit of distance used in astronomy to measure how far light travels in one year. Light moves extremely fast—about 299,792 kilometers per second—so in one year, it travels roughly 9.46 trillion kilometers (or about 5.88 trillion miles). Light years help scientists express the huge distances between stars and galaxies. For example, the nearest star to Earth, Proxima Centauri, is about 4.24 light years away. The term “light year” can be confusing because it sounds like a measure of time, but it actually measures distance.
Bohr Radius
The Bohr radius is a fundamental physical constant that represents the average distance between the nucleus and the electron in a hydrogen atom in its ground state, according to the Bohr model of the atom.
Its value is approximately 5.29177 × 10⁻¹¹ meters (about 0.529 angstroms).
Named after physicist Niels Bohr, who introduced the model in 1913.
It sets a natural length scale in atomic physics and quantum mechanics.
Used to describe atomic sizes and electron orbitals.
Key facts:
Bohr radius ≈ 5.29 × 10⁻¹¹ m
Represents the typical size of a hydrogen atom’s electron orbit
Fundamental to quantum physics and atomic structure
The Bohr radius is essential for understanding atomic dimensions and quantum behavior of electrons.