1 electron volt (eV) is equal to 1.602 x 10^-19 joules (J).
Why use both?
* Joule: The joule is the standard SI unit of energy. It's used in many different fields of physics and engineering.
* Electron volt: The electron volt is a more convenient unit for describing the energy of particles at the atomic and subatomic level. It's directly related to the energy gained by an electron when it moves through an electric potential difference of one volt.
Think of it like this:
* Joule: Think of a joule as a large unit of energy, like the energy you might use to power a light bulb.
* Electron volt: Think of an electron volt as a tiny unit of energy, like the energy an electron might gain from interacting with a photon.
Converting between them:
* To convert from electron volts to joules, multiply by 1.602 x 10^-19.
* To convert from joules to electron volts, divide by 1.602 x 10^-19.
Example:
* A photon of visible light has an energy of about 2 eV. To express this in joules, multiply by 1.602 x 10^-19: 2 eV * 1.602 x 10^-19 J/eV = 3.204 x 10^-19 J.
