The Electromagnetic Spectrum

The Electromagnetic Spectrum is a range of all the different frequencies of electromagnetic waves.
Electromagnetic waves are transverse waves, they can travel through space where other types of waves, like sound, require a medium to travel through.
The spectrum is organised based on the frequency and wavelength of electromagnetic waves.
Electromagnetic waves with the highest frequency have the shortest wavelength and vice versa.

Types of Electromagnetic Waves

Radio Waves: These have the lowest frequencies and longest wavelengths in the electromagnetic spectrum. They are used in wireless communications like TV broadcasts and FM and AM radio.
Microwaves: These are used in microwave ovens and for transmitting information for mobile phones and satellite television.
Infrared Waves: These waves have a higher frequency than microwave and radio waves. They are used by remote controls, thermal imaging cameras, and for transferring data between devices (‘infrared connectivity’).
Visible Light: This part of the spectrum is visible to the human eye. It’s made up of the colours we see in a rainbow - red, orange, yellow, green, blue, indigo, and violet.
Ultraviolet (UV) Radiation: This part of the spectrum has a higher frequency than visible light. It is used in sunbeds and is what causes skin to tan in sunlight. High exposure can also cause skin cancer.
X-Rays: They are used in medical imaging to see inside the body. X-Rays have a higher frequency than UV radiation.
Gamma Rays: These waves have the highest frequency and shortest wavelength of the electromagnetic spectrum. Gamma rays are created in nuclear reactions and used in medical treatments like radiotherapy.

Electromagnetic waves all travel at the same speed in a vacuum, which is the speed of light (3 x 10^8 m/s).
While the speed of these waves is constant, the energy they carry varies. Higher frequency waves like gamma rays carry more energy than lower frequency waves like radio waves.
The energy an electromagnetic wave carries is inversely proportional to its wavelength.
Electromagnetic waves can be reflected, refracted and diffracted just like other types of waves.
They can also be absorbed and emitted by materials, which makes them useful for communications and various technologies.