11.1 What is electromagnetic radiation?(ESADH)

The most common example of electromagnetic (EM) radiation is visible light. Everyone is very familiar with light in everyday life, you can only see things because light bounces off them and enters your eyes. This alone makes it worthwhile to learn about it but there are also very many other applications of EM radiation. It is called electromagnetic because there are electric and magnetic fields making up the radiation. We will look at this in more detail a little later.

In everyday experience, light doesn't seem to have many special properties but it does:

• A huge spectrum: The light we can see (visible EM radiation) is only a small part of all of the EM radiation (electromagnetic spectrum) that exists.

• Nature's speed limit: Nothing moves faster than the speed of light.

• Wave nature: All EM radiation has the ability to behave like a wave which we call wave-like behaviour.

• Particle nature: All EM radiation has the ability to behave like a particle which we call particle-like behaviour.

• No medium required: EM radiation can propagate without a medium through which to move even though they are waves.

Two important things to notice, we have mentioned:

1. waves without a medium and

2. being both a particle and a wave.

We will discuss this in the following sections and in even more detail in Grades 11 and 12.