What is radiation defined as?

Radiation is defined as energy that travels through space as a wave or as a stream of particles. This definition encompasses various forms of radiation, including electromagnetic radiation (such as gamma rays and X-rays) and particulate radiation (such as alpha and beta particles).

Understanding this definition is crucial because it highlights the dual nature of radiation. It can exist in a wave form, as seen with light and radio waves, or in a particle form, with components like electrons or protons. This concept is fundamental in the field of radiation safety and protection, as it informs how different types of radiation interact with matter and their potential effects on human health and the environment.

The other options provided do not accurately capture the comprehensive nature of radiation. For instance, energy that is absorbed by objects refers more to the interaction rather than the definition of radiation itself. Particles losing energy during emission describes a process related to radioactive decay but does not define what radiation is. Lastly, stating that energy cannot be measured contradicts scientific principles, as radiation can be quantified through dosage measurements and detection devices.