Electromagnetic spectrum

Introduction

The arrangement of electromagnetic radiations, either in ascending or descending order of the wavelength and frequency, is called the electromagnetic spectrum. The electromagnetic spectrum has various classes of electromagnetic radiation. However, there exists no sharp division between any two radiations, as the classification exists in Ranges.

The electromagnetic wave was experimentally discovered by Hertz. The fundamental difference between various electromagnetic waves lies in their wavelength and frequencies, as they all travel at the same speed in the vacuum.

Types of the electromagnetic spectrum

There are seven categories of electromagnetic waves:

• Radio waves
• Microwaves
• Infrared waves
• Visible light
• Ultraviolet rays
• X-rays
• Gamma rays

Radio waves

Radio waves are produced by the accelerated motion of charges in conducting wires or oscillating electric circuits. They are extensively used in radio and television communication systems.

Properties of radio waves

•  The frequency range lies between 500kHz to 1000MHz
•  The wavelength range lies between 10^-2 m to 104  m
•  The radio waves can be, reflected, refracted, and diffracted

Uses of radio waves

• Amplitude Modulated (AM), with the frequency band of 530kHz – 1710 kHz, is used in ground wave propagation
• The Short Waves (SW), 1710 kHz – 54 MHz, are used in sky wave communication
• Television waves are in the frequency band of 54 MHz – 890 MHz.
• Frequency Modulated (FM), with the band of frequency ranging from 88 MHz – 108 MHz, is used for FM communication
• Ultra-high frequency waves (UHF), with the frequency band of 300 MHz – 3000 MHz, are used in cellular phone communication

Microwaves

The microwaves are short-wavelength radio waves. These waves are produced by special vacuum tubes called Gunn diodes, magnetrons, and klystrons.

Properties of microwaves

The frequency range of microwaves lies between 1 GHz and 300 GHz.

Uses of microwaves

• Used in radar systems for aircraft navigation
• Used to detect speeds of a tennis ball, Cricket ball, automobiles, etc
• Used in microwave ovens

Infrared waves

Infrared waves are produced by hot bodies. These waves have low frequency and high wavelengths. They are present adjacent to the visible spectrum.

Properties of infrared waves

• The frequency range lies between 1011 Hz to 1014 Hz
• The wavelength range lies between 1 nm to 700 nm
• They have such characteristics that they are also known as heat waves
• Human eyes cannot detect them, but Snakes and certain insects can detect these waves
• These waves are readily absorbed by particles like carbon dioxide, ammonia, water molecules, etc., after getting absorbed by the particles mentioned above, they heat their surrounding environment
• Infrared waves are also responsible for maintaining Earth’s average temperature through the greenhouse effect

Uses of infrared waves

• An infrared lamp is used in physical therapy to treat muscular strain
• It is used as detectors in earth satellites to observe the growth of crops and for security purposes
• It provides electrical energy to satellites by using solar cells
• It is used to take photographs during fog and smoke

Visible rays

Visible rays are a range of electromagnetic spectrums produced by atomic excitation. This is the only range sensitive to human eyes, as the visible light emitted or reflected from the objects makes us see the world around us. It can be detected by the eyes, photocells, and photographic films. Its frequency range lies between 4×1014 Hz to 7×1014 Hz. The wavelength of visible rays lies between 700 nm to 400 nm.

Ultraviolet rays

Ultraviolet rays are produced by the sun, special lamps, and very hot bodies. The frequency range of ultraviolet rays lies between 8×1014 Hz to 5×1016 Hz, while its wavelength ranges from 400 nm to 0.6 nm.

Uses of Ultraviolet rays

• Used in LASIK (laser-assisted in situ keratomileusis) Eye surgery that requires high precision.
• Used in UV lamps that are used to kill germs in water purifiers
• Used for the destruction of bacteria in hospitals and laboratory
• Used in sterilization of surgical instruments

X-rays

X-rays are produced in a tube called an x-ray tube. Also, when a metal target is bombarded with high-energy electrons, such waves are produced. Its frequency range lies between 1016 Hz to 1021 Hz, and its wavelength lies between 10 nm and 10^-4 nm. These waves are detected by photographic films, Geiger tubes, and ionization chambers.

Exposure to X-rays can lead to the destruction of living tissues and be responsible for the mutation (alteration of the genetic code) in extreme cases.

Uses of X rays:

• To detect cracks, fractures, and displacement in bones
• Used in treatment for certain forms of cancer
• Used to detect pearls in oysters, defects in rubber tires and gold

Gamma rays

These are the high-frequency rays that are produced in nuclear reactions and are emitted by radioactive nuclei

Properties of gamma rays

• The Frequency range lies between 1018 Hz to 1022 Hz
• The Wavelength range lies between 10-10 m to 10^-14 m
• Waves show the properties like phosphorescence, fluorescence, polarization, and diffraction
• They have a very high penetrating power

Uses of gamma rays

• Used for cancer therapy
• Provide important information regarding the nuclear structure

Conclusion 

The electromagnetic spectrum is made up of seven electromagnetic waves that have different frequencies and wavelengths. Also, the frequency and wavelength of EM waves are inversely proportional. Spectroscopy is the study of how the different electromagnetic waves interact with the particles of the medium.