Which scale measures all known wavelengths?

The electromagnetic spectrum is the correct choice because it encompasses all known wavelengths of electromagnetic radiation, ranging from radio waves at one end to gamma rays at the other. This spectrum includes various regions such as microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays, each characterized by different wavelengths and energies.

This scale is crucial for understanding a wide variety of phenomena in physics, astronomy, and even applications in electrology, such as the use of light in hair removal technologies. By measuring and categorizing wavelengths, the electromagnetic spectrum provides a comprehensive framework for studying how different types of radiation interact with matter.

Other options refer to more specialized or limited ranges within the discipline. For example, the quantum scale relates more to the behavior of particles at a quantum level, while the thermal scale pertains to temperature measurements and energy transfer, which are not exhaustive of all wavelengths. The optical scale mainly focuses on visible light, thus making it a subset of the broader electromagnetic spectrum.