The electromagnetic spectrum includes all types of electromagnetic radiation. Sun is the primary energy source for our planet, and the energy from the sun travels in the form of electromagnetic radiation. In the spectrum of electromagnetic waves, the electromagnetic spectrum is a range of frequencies, wavelengths, and photon energies ranging from below 1 hertz to above 1025 Hz, equivalent to wavelengths ranging from a few km to a fraction of the size of an atomic nucleus.

The electromagnetic energy travels in electric and magnetic fields through space with the speed of light over a range of frequencies or wavelengths. Electromagnetic radiation constitutes a significant part of our everyday life. Some examples of EM Waves are the visible light we see, the microwave radiations, the X-rays that help doctors detect any injury in our bones or the UV radiations emitted by a hot surface.

Electromagnetic waves are the waves that are generated due to the interaction between vibrating electric and magnetic fields. EM waves consist of an oscillating electric and magnetic field. A collection of electromagnetic waves forms the electromagnetic spectrum. Let us learn in detail about the electromagnetic spectrum.

What is an Electromagnetic Spectrum?

A group of frequencies, wavelengths, and photon energies of electromagnetic waves ranging from the frequencies as low as \(1\,\rm{Hz}\) to as high as \({10^{25}}\,\rm{Hz}\) corresponding to the wavelengths ranging from a few hundred kilometres to a size smaller than the size of an atomic nucleus constitutes the electromagnetic spectrum. Thus, in simple terms, the Electromagnetic spectrum can be defined as the range of all types of electromagnetic radiation. In general, all electromagnetic waves travel at the speed of light in a vacuum. However, the values of respective wavelengths, frequencies, and photon energies will vary for varying types of electromagnetic waves.

Terms related to Electromagnetic Waves

The frequency \(\left( f \right),\) wavelength \(\left( \lambda \right),\) energy \(\left( E \right)\) of an electromagnetic wave are related to each other as:
\(\lambda = \frac{c}{f}\)
\(f = \frac{E}{h}\)
\(E = \frac{{hc}}{\lambda }\)
Where
\(c = 3 \times {10^8}\,{\rm{m}}/{\rm{s}}\) represents the speed of light in a vacuum
\(h = 6.626 \times {10^{ – 34}}\,\rm{J.s}\) represents Planck’s constant.

Electromagnetic Spectrum Used in Daily life

The existence of electromagnetic waves was predicted by Maxwell. At that time, the visible light waves were the only electromagnetic waves that the world was familiar with, and soon enough, scientists discovered ultraviolet and infrared waves. X-rays, radio waves, microwaves, and gamma rays were established during the latter half of the nineteenth century.

The electromagnetic spectrum is a classification of electromagnetic waves based on their frequencies, and it consists of radio waves, microwaves, infrared waves, visible rays, ultraviolet rays, X-rays, and gamma rays. There is no clear distinction between one kind of wave and the next. This classification of waves in the spectrum is done based on their detection or production.

Study Electromagnet

The electromagnetic spectrum consisting of various electromagnetic radiations can further be sub-categorized. The subranges of the electromagnetic spectrum are commonly referred to as portions. Different electromagnetic radiations, along with their frequency and wavelength, are tabulated below:

The electromagnetic spectrum is represented as:

Radio Waves

1. These waves are produced by the accelerated motion of the charged particles through conducting wires.
2. They are used for the transfer of radio, television and communication signals.
3. These waves lie within the frequency range from \(3\,{\rm{kHz}}\) to about \(300\,{\rm{MHz}}.\)
4. Cellular phones use radio waves to transmit voice communication in the ultrahigh-frequency (UHF) band.
5. A radio captures radio waves that radio stations transmit. Gases and stars can also emit radio waves in space. Radio waves are mainly used for TV/mobile communication.

Microwaves

1. Microwaves are electromagnetic radiation with frequencies in the range of a few gigahertz (GHz) range.
2. These are produced by special vacuum tubes called klystrons, magnetrons and Gunn diodes.
3. Since the wavelengths of microwaves are small, these are widely used in aircraft navigation.
4. These radiations are used in microwaves and help in heating food at homes or offices. Astronomers also use it to determine and understand the structure of nearby galaxies and stars.

Infrared Rays

1. Hot bodies and molecules produce infrared waves, and hence these are also referred to as heatwaves.
2. Infrared radiations lie close to the low-frequency or long-wavelength end of the spectrum of visible light.
3. The greenhouse effect caused by these radiations is imminent for maintaining warmth and the average temperature on the earth.
4. These radiations get trapped in the earth’s atmosphere by greenhouse gases like carbon dioxide and water vapour.
5. These radiations are employed in night vision goggles. These devices are capable of reading and capturing the infrared light emitted by objects in the dark. In space, interstellar dust is mapped using infrared light. Electronic devices emit infrared radiations and are widely used in the remote switches of various household devices.

Visible Rays

1. Visible rays are the radiations that can be detected by the human eye and are, therefore, the most prominent form of electromagnetic waves.
2. These lie within the frequency range from \(4 \times {10^{14}}\,{\rm{Hz}} – 7 \times {10^{14}}\,{\rm{Hz}}\) or within the wavelength range \(400\,{\rm{nm}} – 700\,{\rm{nm}}{\rm{.}}\)
3. The visible light rays reflected or emitted from the objects around us help us see the world, and for different animals, the range of visible radiation is different.
4. The devices like bulbs, lamps, candles, LED’s, tube lights etc., emit light in the visible range of the electromagnetic spectrum.

Ultraviolet Rays

1. The sun is the major source of ultraviolet radiation on the earth, but the ozone layer absorbs most UV radiation, reaching the earth’s atmosphere.
2. UV radiation lies within the range of \(400\,{\rm{nm}} – 1\,{\rm{nm}}{\rm{.}}\)
3. Special lamps and very hot bodies emit these radiations, and in large quantities, they can cause substantial harm to humans. It causes skin tanning and burns.
4. These radiations are used in high precision applications such as LASIK or laser-based eye surgery because these can be focussed into thin beams.
5. UV lamps are installed in water purifiers to kill the germs present in the water.
6. Welders use special goggles to protect their eyes while working with the UV welding arcs.

X-Rays

1. This electromagnetic radiation lies beyond the UV region in the electromagnetic spectrum and is significantly useful in the medical industry.
2. X-ray radiation lies within the wavelength range of \(1\,{\rm{nm}} – {10^{ – 3}}\,{\rm{nm}}.\)
3. X-rays can be generated by bombarding a metal target with high energy electrons.
4. X-rays are a diagnostic tool in the field of medicine and are immensely useful in treating certain forms of cancer. A doctor uses an x-ray machine to take a scan of our bone or teeth to detect the area of the problem. Overexposure to x-rays can cause damage or destruction to the healthy tissues of the organisms. Hence care must be taken while dealing with x-rays.
5. At the airport checkpoint, the security personnel use it to check through the luggage of the travellers. X-rays are also given out by the hot gases in the universe.

Gamma-Rays

1. The universe is the biggest generator of gamma-ray.
2. These radiations belong to the upper-frequency range of the electromagnetic spectrum.
3. The wavelength of gamma rays lie within the range of \({10^{ – 12}}\,{\rm{m}} – {10^{ – 14}}\,{\rm{m}}.\)
4. These high-frequency radiations are emitted by radioactive nuclei and are produced during nuclear reactions too.
5. Gamma rays have wide applications in the medical field and are used to destroy harmful cancer cells. Doctors use gamma-ray imaging to look inside patient’s bodies.

What is Spectroscopy?

The study of how different electromagnetic waves interact with matter is known as spectroscopy. In simple terms, spectroscopy is a tool for determining the emission and absorption of light and other radiation as it interacts with matter in terms of wavelength or frequency of the radiation.

We can use the analysis of the electromagnetic spectrum of a substance to learn a lot about it. A ray of light gets scattered as it passes through matter. It interacts with atoms and molecules of the given matter, and based on their frequencies of resonance; these atoms interact with the light waves having similar frequencies. Certain characteristic frequencies are emitted during the collision of light rays with an atom in an excited state, resulting in a line spectrum. This line spectrum consists of a set of emission lines, and it is not continuous. The light produced has detached wavelengths. An absorption spectrum is produced when the light having continuous wavelengths is passed through a material having a low density. The atoms and molecules having characteristic frequencies similar to the light waves will be absorbed, and the resulting spectrum will be continuous with a few lines missing.

Applications of Electromagnetic Spectrum

Maxwell gave the first indication of the existence of the entire electromagnetic spectrum. His equations gave an idea regarding the existence of an infinite number of frequencies of electromagnetic radiation. The electromagnetic spectrum is an arrangement of various radiations based on their frequencies and wavelengths. Some applications of EM-spectrum are:
1. Hertz discovered radio waves and microwaves. These waves led to the development of wireless television and radio and mobile communication.
2. The highly energetic UV radiation is useful for the ionization of atoms, helping initiate various chemical reactions.
3. Paul Villard discovered the gamma rays. These are used for developing nuclear medicine and for experiments involving ionization.
4. Roentgen discovered x-rays. These are used for the detection of ailments and deformities in the bones and teeth.
5. We can see the world around us because of the visible light portion of the electromagnetic spectrum. This portion of the electromagnetic spectrum helps us see all the objects, including the colours.

Summary

A collection of electromagnetic waves forms the electromagnetic spectrum. It is a group of frequencies, wavelengths, and photon energies of electromagnetic waves ranging from frequencies as low as \(1\,{\rm{Hz}}\) to as high as \({10^{25}}\,{\rm{Hz}}{\rm{.}}\) Maxwell gave the first indication of the existence of the entire electromagnetic spectrum. His equations gave an idea regarding the existence of an infinite number of frequencies of electromagnetic radiation. The electromagnetic spectrum is a classification of electromagnetic waves based on their frequencies, and it consists of radio waves, microwaves, infrared waves, visible rays, ultraviolet rays, X-rays, and gamma rays. There is no clear distinction between one kind of wave and the next. This classification of waves in the spectrum is done based on their detection or production.

FAQs

Q.1. What is the electromagnetic spectrum?
Ans: The electromagnetic spectrum is the classification of radiations based on their frequencies or wavelengths.

Q.2. Define electromagnetic waves.
Ans: Electromagnetic waves are vibrations that consist of electric and magnetic fields oscillating perpendicular to each other.

Q.3. Write a few uses of UV rays.
Ans: UV rays are used to kill bacteria, cure inks and resins, and create fluorescent effects and phototherapy.

Q.4. Define spectroscopy.
Ans: Spectroscopy is the study of emission and absorption of light and other electromagnetic radiation by matter depending on the wavelength or frequency of the radiation.

Q.5. What is the source of gamma rays?
Ans: The universe is the biggest source of gamma rays. On earth, gamma rays are produced during lightning, nuclear explosions and radioactive decays.

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