Which term refers to the set of all wavelengths or frequencies of electromagnetic radiation?

• A. electromagnetic radiation
• B. electromagnetic spectrum
• C. wavelength
• D. frequency

Answer: (B)

The set of all wavelengths or frequencies of electromagnetic radiation is called the electromagnetic spectrum. This term uniquely describes the complete range of EM radiation, from the longest wavelengths used in radio waves to the shortest gamma rays, with visible light just a small part of the continuum. It’s the best description here because it denotes the entire range rather than a single wavelength, a single type of radiation, or a single property. Wavelength and frequency are individual characteristics of a wave, so they refer to one point on the spectrum or to a specific wave, not the whole gamut. Remember that wavelength and frequency are connected by c = λν in vacuum, so you can move between the two descriptions depending on what you’re analyzing.