Which type of wave has the least energy in the electromagnetic spectrum?

In the electromagnetic spectrum, energy is directly related to the frequency of the waves; as frequency increases, so does the energy of the waves. Radio waves are characterized by the lowest frequencies and, consequently, the least amount of energy among the various types of electromagnetic radiation.

Microwaves, while lower in energy than X-rays and gamma rays, still possess more energy than radio waves. X-rays and gamma rays have much higher frequencies, which means they carry significantly more energy compared to both microwaves and radio waves.

Therefore, choosing radio waves as the type of wave with the least energy is correct because they occupy the lower end of the electromagnetic spectrum, where the frequency and energy are at their minimum. This understanding aids in grasping the broader concepts of electromagnetic radiation and its applications in various fields, from communication to medical imaging.