What increases as the wavelength of electromagnetic radiation decreases?

As the wavelength of electromagnetic radiation decreases, the energy of the radiation increases. This relationship is described by the equation that expresses the energy of a photon: Energy (E) is directly proportional to the frequency (ν) of the radiation, and since frequency is inversely proportional to wavelength (λ), the relationship can be expressed as E = hν = hc/λ, where h is Planck's constant and c is the speed of light. Thus, as the wavelength gets shorter, the energy increases.

The other options do not have a direct relationship with the wavelength of electromagnetic radiation. The number of atoms and electrons does not inherently change with the wavelength of radiation; these quantities are determined by the material being analyzed rather than the radiation itself. Similarly, matter itself is not affected by the changes in electromagnetic wavelength in the context described; rather, it is the energy associated with the radiation that varies with the wavelength. Therefore, the correct answer highlights the fundamental property of electromagnetic radiation related to energy and wavelength.