Here's why:

* Electromagnetic Spectrum: This spectrum encompasses all types of electromagnetic radiation, which travel as waves. It's categorized by the wavelength and frequency of the radiation.

* UV Rays, Visible Light, and Infrared Rays: These are all forms of electromagnetic radiation and therefore part of the electromagnetic spectrum.

* Alpha Rays: Alpha rays are not electromagnetic radiation. They are a type of ionizing radiation consisting of two protons and two neutrons bound together, essentially a helium nucleus. They are emitted during radioactive decay.

Let me know if you have any other questions!