The fundamental unit of electric charge carried by a single electron.The electron charge is the fundamental unit of electric charge, denoted by the symbol e, and is the amount of negative charge carried by a single electron. It is one of the most precisely measured constants in physics, with a value of approximately 1.602 × 10⁻¹⁹ coulombs. This quantity is not just a property of electrons; it is the basic quantum of charge in nature, meaning that all free electric charges are integer multiples of e, a fact known as charge quantization.
The electron charge was first measured by Robert Millikan in his famous oil-drop experiment in 1909, which earned him the Nobel Prize in Physics in 1923. Millikan's careful measurements showed that the charge on oil droplets was always a multiple of a single value, providing direct evidence for charge quantization.
The electron charge is a fundamental property of the electron, a point-like particle in the Standard Model. It determines the strength of the electromagnetic interaction between electrons and other charged particles, such as protons and photons. The value of e is so fundamental that it appears in countless equations, from the fine-structure constant that characterizes atomic spectra to the Coulomb force law that governs electric interactions.
The electron charge is essential in electronics, where it determines the current in circuits (as the charge per electron times the number of electrons flowing per second), and in electrochemistry, where it relates to the Faraday constant used in electrolysis and battery design.
The electron charge is so small that a typical lightning bolt carries about 10²⁰ electrons, which is more than the number of stars in the observable universe.








