CONCEPTS

# What is the electromagnetic spectrum?

We explain what the electromagnetic spectrum is, in which regions it is divided, what it is used for and how it was discovered.

1. ### What is the electromagnetic spectrum?

The electromagnetic spectrum is the total range of all electromagnetic radiation . It extends from the shortest wavelength (for example, gamma rays) to the longest wavelength, such as radio waves.

It consists of various sub-ranges or portions, whose limits are not entirely defined and tend to overlap. Each strip of the spectrum is distinguished from the others in the behavior of its waves during the emission, transmission and absorption , as well as in its practical applications.

Electromagnetic waves are vibrations driven by the electric and magnetic fields of the universe . These waves are able to propagate in a vacuum at a speed very close to that of light .

When talking about the electromagnetic spectrum of an object, we refer to the amount of electromagnetic radiation that a substance emits (called emission spectrum) or absorbs (called absorption spectrum), thus generating an energy distribution in the form of a set of electromagnetic waves.

The characteristics of this distribution depend on the frequency , amplitude and wavelength of the same waves, as well as the energy levels of the moving particles that compose them: the photons.

The electromagnetic spectrum was discovered following the experiments and contributions of the British James Maxwell , who discovered the presence of electromagnetic waves and formalized the equations of his study (known as Maxwell’s equations).

1. ### Regions of the electromagnetic spectrum

The electromagnetic spectrum, in principle, is infinite and continuous , but so far we have been able to know different regions of it, known as bands or segments, according to their specific wave characteristics. Its regions are, from least to greatest :

• Gamma rays . With a wavelength less than 10 × 10 -12 m, a frequency greater than 30 × 10 18 Hz and an amount of energy greater than 20 × 10 -15
• X rays . With a wavelength less than 10 × 10 -9 m, a frequency greater than 30 × 10 15 Hz and an amount of energy greater than 20 × 10 -18
• Radiation EUV . With a wavelength less than 200 × 10 -9 m, a frequency greater than 1.5 × 10 15 Hz and an amount of energy greater than 993 × 10 -21
• Near ultraviolet radiation . With a wavelength less than 380 × 10 -9 m, a frequency greater than 7.89 × 10 14 Hz and an amount of energy greater than 523 × 10 -21
• Visible spectrum of light . With a wavelength less than 780 × 10 -9 m, a frequency greater than 384 × 10 12 Hz and an amount of energy greater than 255 × 10 -21
• Near infrared . With a wavelength less than 2.5 × 10 -6 m, a frequency greater than 120 × 10 12 Hz and an amount of energy greater than 79 × 10 -21
• Medium infrared . With a wavelength less than 50 × 10 -6 m, a frequency greater than 6 × 10 12 Hz and an amount of energy greater than 4 × 10 -21
• Far or sub millimeter infrared . With a wavelength less than 1 × 10 -3 m, a frequency greater than 300 × 10 9 Hz and an amount of energy greater than 200 × 10 -24
• Microwave radiation . With a wavelength less than 10 -2 m, a frequency greater than 3 × 10 8 Hz and an amount of energy greater than 2 × 10 -24
• Ultra high frequency radio waves . With a wavelength less than 1 m, a frequency greater than 300 × 10 6 Hz and an amount of energy greater than 19.8 × 10 -26
• Very high frequency radio waves . With a wavelength less than 10 m, a frequency greater than 30 × 10 6 Hz and an amount of energy greater than 19.8 × 10 -28
• Short wave radio . With a wavelength less than 180 m, a frequency greater than 1.7 × 10 6 Hz and an amount of energy greater than 11.22 × 10 -28
• Medium wave of radio . With a wavelength less than 650 m, a frequency greater than 650 × 10 3 Hz and an amount of energy greater than 42.9 × 10 -29
• Longwave radio . With a wavelength less than 10 × 10 3 m, a frequency greater than 30 × 10 3 Hz and an amount of energy greater than 19.8 × 10 -30
• Very low frequency radio wave . With a wavelength greater than 10 × 10 3 m, a frequency less than 30 × 10 3 Hz and an amount of energy less than 19.8 × 10 -30

Thus, the regions of the electromagnetic spectrum are gamma rays, x-rays, ultraviolet radiation, visible spectrum, microwaves, and radiofrequency.

1. ### Uses of the electromagnetic spectrum

The uses of the electromagnetic spectrum can be very diverse, depending on each region of it. For example:

• Radio frequency waves are used to transmit information over the air, such as radio, television or Wi-Fi Internet broadcasts .
• Microwaves are also used to transmit information, such as mobile (cellular) telephone signals or microwave antennas. It is also used by satellites as a mechanism for transmitting information to the ground. And they serve, at the same time, to heat food in microwave ovens.
• Ultraviolet radiation is emitted by the Sun and absorbed by plants for photosynthesis , as well as by our skin when we tan. It also feeds the fluorescent tubes and allows the existence of facilities such as solariums.
• Infrared radiation instead is what transmits heat from the Sun to our planet, from a fire to the objects around it, or from a heating inside our rooms.
• The spectrum of visible light makes things visible, as we know. In addition, it can be used for other visual mechanisms such as cinema , flashlights, etc.
• X-rays are used in medicine to make visual impressions of the inside of our bodies, such as our bones, while gamma rays, much more violent, are used as a form of radiation therapy or treatment for cancer , since they destroy DNA of cells that reproduce messily.
1. ### Importance of the electromagnetic spectrum

In the contemporary world, the electromagnetic spectrum is a key element for telecommunications and the transmission of information . It is also essential in exploratory techniques (radar / sonar type) of outer space, when not as a way of understanding astronomical phenomena distant in time and space.

It has various medical applications and practices that are also part of what we take today as quality of life. That is why its manipulation is, without a doubt, one of the great discoveries of humanity.