What defines the electromagnetic spectrum?

The electromagnetic spectrum is defined as the total range of wavelengths of electromagnetic radiation. This spectrum encompasses all types of electromagnetic waves, which include radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays. Each type of electromagnetic wave has a distinct wavelength or frequency, collectively forming a continuous spectrum from the shortest wavelength (gamma rays) to the longest wavelength (radio waves). Understanding the electromagnetic spectrum is fundamental in fields such as physics, telecommunications, and even art and design.

The other options do not encompass the full scope of the electromagnetic spectrum. The range of colors visible to the human eye pertains only to a small portion of the spectrum, specifically the visible light range. The colors that create a rainbow refer to the specific wavelengths of light that can be seen by humans, which also fall within the visible light portion of the spectrum. Lastly, the mention of sound waves pertains to a completely different phenomenon, as sound is mechanical wave propagation through mediums and is not part of the electromagnetic spectrum. Thus, the characterization of the electromagnetic spectrum as the total wavelengths of electromagnetic radiation is the most accurate and comprehensive definition.