Introduction to Electromagnetic Waves

Electromagnetic waves are a type of wave that can travel through the vacuum of space.
They are waves of energy that spread outwards from an originating source.
Electromagnetic waves consist of oscillating electric and magnetic fields, which are perpendicular to each other and the direction of travel of the wave.
Important characteristics of electromagnetic waves include their wavelength, frequency, and speed.

The Electromagnetic Spectrum

The electromagnetic spectrum is an arrangement of electromagnetic waves according to their wavelengths and frequencies.
Its ranges include, from longest wavelength to shortest: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
Visible light is a small part of the spectrum, which human eyes are sensitive to. It includes all the colours that we can see, from red (longest wavelength) to violet (shortest wavelength).
Different parts of the electromagnetic spectrum have different impacts, uses, and hazards due to their different energy levels.

Interaction with Matter

When electromagnetic waves encounter matter, they can be reflected, absorbed, or transmitted.
The behaviour of the electromagnetic wave depends on the type of material and the frequency of the wave.
For example, visible light is reflected by a mirror, absorbed by an opaque object, and transmitted by clear materials like glass or air.

Tracking the Speed of Light

In a vacuum, all electromagnetic waves travel at the same speed — the speed of light.
The speed of light, represented as ‘c’, is approximately 3 x 10^8 metres per second.
Despite their different wavelengths and frequencies, all types of electromagnetic waves maintain this speed.

Understanding electromagnetic waves and their properties is essential, as they have a multitude of applications. These range from microwave ovens and radio broadcasting to medical imaging with X-rays and treatment with radiation therapy.