# The electromagnetic spectrum

In today’s post we are going to focus on the study of the electromagnetic spectrum, what it consists of and what are the rays that form it.

Definition: We call the electromagnetic spectrum the set formed by waves, from those with the longest length (for example, radio waves or waves that belong to sounds that can be perceived by the human ear) to the shortest waves ( for example, Gamma rays or cosmic rays).
The fundamental characteristics to study and describe the different types of waves are, apart from the wavelength; energy and frequency.
Observation: We must take into account the greater the wavelength, the lower the frequency, and conversely, the shorter the wavelength, the greater the frequency.
From the previous observation, we can also give an analogous definition for the electromagnetic spectrum by referring to the frequency of the waves.

Definition: When we refer to an object, we call the electromagnetic spectrum the electromagnetic radiation that can absorb or emit said substance. Spectroscopes are used to observe the spectra, which also allow us to measure the wavelength, as well as the frequency and energy (or intensity of the radiation).

The waves that form the electromagnetic spectrum and that we can see in the following image are (describing them from those with the shortest wavelength to those with the longest):

– Gamma Rays: They are the waves that have the shortest wavelength, and therefore, the highest frequency. They are the most penetrating waves known, and they also have high energy that allows them to travel long distances through the air.
– X-rays: These are located between the Gamma rays and the ultraviolet rays, therefore they have more energy than the ultraviolet rays. They are used in a multitude of industrial and scientific applications. Above all, its use in medicine stands out, where the use of radiographs is very important. Despite everything, they can be very dangerous, since they consist of a form of ionizing radiation emitted by the electrons outside the nucleus.
– Ultraviolet rays (UV):These waves are in the frequency range that is located between 7.5 × 10 ^ 14 Hz and 3.0 × 10 ^ 16 Hz. The best known types are UV-A (ultraviolet-A) and UV-B (ultraviolet-B) rays. Many of the rays of the Sun that the Earth receives, and also some that provide certain ray lamps; They are of the UV-A type, so it is dangerous to expose yourself to them excessively since skin cancer can appear. Although it is also true that if exposure to them is moderate, they favor the creation of vitamin D. But as we already know, the ozone layer helps us protect ourselves from these rays by acting as a natural filter.
-Visible light (or visible spectrum):It is the part of the electromagnetic spectrum that the human eye is able to detect. It covers all colors: from blue at 400 nm to red at 700 nm.
-Infrared (IR) rays (or thermal radiation): Infrared is in the frequency range that is located between 3.0 × 10 ^ 11 Hz up to 3.8 × 10 ^ 14Hz. The vast majority of infrared rays we receive are from the Sun, although any molecule that has a temperature above 0ºKelvin emits infrared rays. Infrared rays are very useful for meteorology, since from a photo of the Earth from a satellite using infrared rays, the temperature in each area of ​​the Earth can be known, depending on the different colors that appear.
– Radio waves:Finally, radio waves are those with the longest wavelength. They are mainly used for television, mobile phones and radio.