Frequency (ν) is the number of wave cycles that pass a fixed point per second; its SI unit is the hertz (Hz). It is inversely related to wavelength, so a wave of higher frequency has a shorter wavelength. For electromagnetic radiation, a higher frequency corresponds to a higher energy per photon.

频率(ν)是每秒通过某固定点的波循环数;其国际单位是赫兹(Hz)。它与波长成反比,故频率越高的波波长越短。对于电磁辐射,频率越高对应每个光子的能量越高。