1.1 What is Radiation?
A fundamental introduction to the concept of radiation, its forms, and how it is a natural part of our world.
The Basic Definition
In simple terms, **radiation** is energy traveling through space in the form of waves or particles. It can be found all around us, from the sunlight that warms the Earth to the electromagnetic waves that power our cell phones and Wi-Fi. This energy comes in a wide range of types, each with different properties and effects.
Types of Radiation
Radiation is generally categorized into two main types based on its energy:
- Ionizing Radiation: This is radiation with enough energy to "ionize" atoms—that is, to knock electrons out of their orbits. This process can be harmful to living organisms. Examples include X-rays, gamma rays, and alpha and beta particles.
- Non-Ionizing Radiation: This is radiation with lower energy that is not strong enough to ionize atoms. It can still transfer energy (e.g., heat), but it is generally considered less harmful in small doses. Examples include radio waves, visible light, and microwaves.
Where Does Radiation Come From?
Radiation is present in our environment from both natural and human-made sources.
- Natural Sources: We are constantly exposed to natural background radiation from cosmic rays (from outer space), terrestrial radiation (from radioactive elements in the Earth's crust), and internal radiation (from elements like Potassium-40 naturally present in our bodies).
- Artificial (Human-Made) Sources: These are sources created by humans, such as X-ray machines used in medical diagnosis, nuclear power plants, and certain industrial applications. While these sources contribute to our overall exposure, they are carefully controlled and regulated.