Electromagnetic radiation:
Electromagnetic radiation comprises the properties of both a wave and a particle. The latter can be explained in terms of quanta or photons. The former can be explained through wavelength (λ) - the distance among the crests of different waves, and frequency (υ) - the number of waves which pass a specific point each second. Frequency is computed in hertz (Hz), which is similar as cycles per second. The energy of electromagnetic radiation is related to frequency and wavelength through the following equation:
E = hυ= hc / λ
In which h = Planck's constant (6.63 × 10-34 J s-1), and c is the velocity of light (2.99792458 × 108 m s-1).
Hence, as much the higher the frequency of radiation, as higher the energy. On the other hand, as much the higher the wavelength, as lower the energy. So in the visible spectrum, violet light (λ = 400 nm) has a higher energy than red light (λ = 750 nm).