Electromagnetic waves. Theory, propagation and applications

What are electromagnetic waves

Electromagnetic waves are periodic disturbances of electric and magnetic fields that travel through space, carrying energy. Electromagnetic waves cover a broad range of frequencies, from radio waves to gamma rays, and include familiar phenomena such as visible light. Studying them allows us to understand how energy travels through different media and lays the groundwork for key technological applications in communications, medicine and science.

Electromagnetic spectrum

The electromagnetic spectrum includes all possible electromagnetic waves, arranged according to their frequency or wavelength. From low-frequency waves such as radio waves to high-energy radiation like gamma rays, each range has unique characteristics and applications. Understanding this spectrum is essential for studying physical phenomena and developing technologies in telecommunications, medicine, astronomy and other fields.

Radio waves

These have the lowest frequency and longest wavelength. They are mainly used in communications, broadcasting and radar.

Microwaves

Microwaves have shorter wavelengths than radio waves and are used in telecommunications, radar and microwave ovens.

Infrared

Infrared waves are associated with heat and are used in thermography, remote controls and sensors.

Visible light

This is the part of the spectrum detectable by the human eye and forms the basis of vision, photography and many optical technologies.

Ultraviolet

Ultraviolet light has more energy than visible light and is used in sterilisation, fluorescence and atmospheric studies.

X-rays

With high energy, X-rays can penetrate tissues and materials, making them essential in medicine, security and structural analysis.

Gamma rays

Gamma rays have the highest energy and are used in medicine, nuclear physics and astrophysics to study high-energy processes.

Propagation of electromagnetic waves

The propagation of electromagnetic waves describes how these waves travel through different media, interacting with matter and with electric and magnetic fields. Understanding the mechanisms of electromagnetic wave propagation helps explain phenomena such as signal transmission, reflection, refraction and attenuation, which are fundamental for engineering and communications.

Propagation in vacuum

In a vacuum, electromagnetic waves travel at the speed of light without loss of energy, maintaining their frequency and wavelength.

Propagation in material media

When passing through air, water or solids, waves may change speed and direction due to refraction, dispersion and absorption, which affects their reach and quality.

Reflection and refraction

Waves may be reflected by conductive surfaces or refracted when passing between different media, key phenomena in antennas, optics and telecommunications.

Attenuation and dispersion

During propagation, the energy of the wave may decrease (attenuation) or disperse, affecting the intensity and clarity of the signal. This is relevant for radio, microwaves and fibre optics.

Polarisation

This describes the orientation of the wave’s electric field and allows control over the direction and effects of waves, applicable in antennas and optical filters.

Applications of electromagnetic waves

Electromagnetic waves are the basis of multiple technologies we use daily and of advanced communication and diagnostic systems. They enable information transmission via radio, television, mobile phones and wireless internet. Their ability to interact with matter is also harnessed in radar, global positioning systems, medical imaging technologies such as magnetic resonance imaging, and in security and industrial control devices. In addition, high-frequency waves like microwaves and lasers are essential in telecommunications, scientific research and military applications. Understanding these applications helps to relate theoretical concepts to concrete phenomena and real-world technologies.