The whole range of radiation which extends in frequencies from 1023 cycles per second to 0 cycle per second and in wave lengths from 0.001 to infinity, thus including gamma rays, X rays, ultraviolet, visible light, infrared, microwaves, radio waves, and alternating current.

【理】电磁频谱。其频率范围为每秒10²³ 周至0周，波长0.001埃至无限大，因而包含了伽玛射线、X射线、紫外线、可见光、红外线、微波、无线电波、及交流电。