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Electromagnetic Spectrum Definition
In simple terms, the Electromagnetic spectrum can be defined as the range of all types of electromagnetic radiation and waves. All celestial bodies emit electromagnetic energy of different wavelengths. Mostly, electromagnetic waves tend to travel at speeds that is similar to the speed of light in a vacuum.
Light is a specific type of electromagnetic radiation that can be seen and detected by the human eye, but this energy generally occurs at a wide range of wavelengths. The spectrum of waves is further divided into sections based on their wavelength. The shortest waves are gamma rays, having wavelengths of 10-6 microns or less. The longest waves are radio waves, having wavelengths is of many kilometres.
Electromagnetic Waves in Electromagnetic Spectrum
The entire electromagnetic spectrum is given by the following;
Radio: A radio fundamentally captures radio waves that are further transmitted by radio stations. Radio waves can also be produced by gases and stars in space. Radio waves are largely used for TV or mobile communication. Extremely low frequency (ELF) radio waves of about 1 kHz or kilohertz are used to communicate with submerged submarines.
The capability of radio waves to penetrate saltwater is linked to their wavelength that is the longer the wavelength, the farther radio waves can penetrate. Saltwater is a good conductor of electricity, hence radio waves are strongly absorbed by it, and thus very long wavelengths (such as radio waves have long wavelengths) are required to reach a submarine under the water surface.
Microwave: This type of radiation is commonly found in microwaves and thus helps in cooking. It is also used by astronomers to comprehend the structure of galaxies and stars in space. Microwaves are referred to as the highest-frequency electromagnetic waves that can be formed by currents in macroscopic circuits and devices.
Infrared: It is used extensively in night vision goggles. In space, infrared light is used to map interstellar dust. Infrared radiation is commonly produced by thermal motion and the vibration and rotation of atoms and molecules.
X-ray: X-rays are used in many instances. For instance, a doctor uses an x-ray machine to capture an image of our bone or teeth. Airport security personnel use X-rays to see through our bags. X-rays have harmful effects on living cells like those of ultraviolet radiation, and they can be more penetrating, thus affect the surface layers of cells.
Gamma-ray: It has an extensive application in the medical field. The universe is the biggest producer or generator of gamma rays. Soon after nuclear radioactivity was first noticed in the year 1896, it was found that at least three different types of radiation were being emitted. It was found that the most penetrating nuclear radiation was the gamma-ray (γ ray) and have an extremely high frequency.
Generally, at higher frequencies, γ rays are more penetrating and more destructive to living tissue. Gamma radiation produced from radioactive materials is also used in nuclear medicine.
Ultraviolet: The main source of ultraviolet radiation is the sun. Hot materials that are present in space also produce UV radiation. Ultraviolet is also formed by atomic and molecular motions and electronic transitions. The wavelengths of ultraviolet ranges from about 400 nm to about 10 nm.
Visible: Visible light can be detected by the naked eye. Stars, bulbs, etc. emit visible light. Visible light is the narrow section of the electromagnetic spectrum to which the human eye responds. Visible light is commonly formed by vibrations and rotations of atoms and molecules, and also by electronic transitions in atoms and molecules. The receivers or detectors of light largely utilize electronic transitions.
Spectroscopy is a method used to study the interaction of different electromagnetic waves with matter.
Significance of Electromagnetic Spectrum
The electromagnetic waves in these different bands have different features depending upon their production and interaction with matter. Maxwell’s equations projected the existence of a countless number of frequencies of electromagnetic waves, all moving with the speed of light.
Nevertheless, the key significance of the electromagnetic spectrum is that it can be used to categorize electromagnetic waves and also helps in arranging them according to different frequencies or wavelengths.
Practical Applications of Electromagnetic Waves
● The visible light portion of the electromagnetic spectrum helps us to see all the objects, as well as the colours.
● The X-rays discovered by Roentgen is quite useful in medicine in recognizing various ailments or deformities in bones.
● The high ultraviolet radiation usually has high energies used to ionize the atoms, hence causing many chemical reactions.
● The gamma rays discovered by Paul Villard are also useful for the ionization process.
Electromagnetic Radiation Equation
Electromagnetic radiation is generally expressed in terms of energy (or abbreviated as E), wavelength( or represented as λ), frequency.
Frequency is usually measured in cycles per second (Hertz or Hz).
Wavelength (λ) is commonly measured in metres.
Energy is measured in electron volt ( eV).
Each of these three quantities mentioned above are linked to each other in a specific scientific way.
f = c/λ
f = E/h
E = hc/λ
c represents the speed of light in a vacuum
h represents is Planck’s constant that is 6.62607015×10−34 J·s
Electromagnetic Spectrum Examples
Q1. What are the frequency and wavelength of an Electromagnetic wave of energy 5.83 x 10-19 J?
Answer: We know the Frequency(f) = E/h Where,
E represents the energy
h represents the planks constant that is 6.62×10−34 J·
So frequency is 8.80 x 1014 Hertz or Hz
We know that Wavelength ( or λ) = c/f Where, c represents the speed of light that is 3 x 108
f represents the frequency
wavelength = 3 x 108 / 8.80 x 1014
= 0.3409 x 10-6 metres
Electromagnetic Spectrum Citations