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### Planck-Einstein relation

An electromagnetic wave can only emit energy in quanta of

E=h ν

##### Explanation

The **Planck-Einstein relation** for a wave reads

E=h ν

where

hPlanck constant νFrequency

##### Alternative 1

For the angular frequency it is

E=h ω

where

ℏ Reduced Planck constant ωAngular frequency

## HistoryIn 1900, the German physicist Max Planck came up with the hypothesis of the quantization of energy. In 1905, German physicist Albert Einstein explained the photoelectric effect with it. In honor of their joint contributions, this relation is now often referred to as the Planck-Einstein relation. |