電磁波係咩能量 ? (除左visible light係光能)

Perhaps you can look at the situation this way: waves are energy-carriers. The energy a wave carries is reflected by the associated frequency (or wavelength, depending on the speed of propagation).

Supplement: the ionizing power of Gamma rays is due to the fact that its energy is high enough to overcome the strong attraction between the electrons and the nucleus of an atom, resulting in the ionization of the atom.