Which of the following is NOT an example of electromagnetic radiation?

Alpha particles are indeed not an example of electromagnetic radiation. Unlike X-rays, radio waves, and microwaves, which are forms of electromagnetic radiation that travel in waves at the speed of light, alpha particles are a type of ionizing radiation consisting of two protons and two neutrons. They are emitted from the nucleus of certain heavy atoms during radioactive decay and are classified as particulate radiation rather than electromagnetic radiation.

On the other hand, the examples provided in the other choices, including X-rays, radio waves, and microwaves, are all part of the electromagnetic spectrum. They share the characteristic of oscillating electric and magnetic fields that propagate through space. Understanding the distinction between electromagnetic radiation and particulate radiation, like alpha particles, is crucial in the study of radiation safety and protection.