Watt Hour (Wh)
The watt-hour, symbolized as Wh, represents the energy consumed when one watt of power is used for one hour, equivalent to 3,600 joules. Introduced with the spread of electrical systems in the late 19th century, the watt-hour is a practical unit for measuring smaller-scale electrical consumption, such as that of batteries and small devices. It is widely used in electronics, computing, and renewable energy storage. While large-scale power use is measured in kilowatt hours, watt-hours provide fine-grained detail for portable and household applications.
Electronvolt (eV)
The electronvolt, symbolized as eV, is primarily used in atomic, nuclear, and particle physics. It is the energy gained by an electron moving through a one-volt potential. The electronvolt enables scientists to measure very small energy changes at the atomic scale. Introduced in the early 20th century, it is standard for describing energy in atoms, photons, and particles. The electronvolt adds the necessary precision in modern physics and works in conjunction with larger units, such as joules and kilojoules.