What is Electromagnetic Spectrum?
Electromagnetic radiation happens all around us. It is produced as the result of interaction between electric and magnetic fields. The fields exist together. Electromagnetic waves tend to have a large range of frequencies/wavelengths.
Radio waves, microwaves, infrared waves, visible light, ultraviolet, x-rays, and gamma rays are the seven types of electromagnetic spectrum.
Radio waves are used in TV and for radio transmissions. Microwaves are primarily used for mobile phone links. Infrared waves find their application in certain alarm systems.
Visible light is used by humans and other animals to gather information about their surroundings. On the other hand, ultraviolet rays are used in tanning beds.
While X-rays are used in radiotherapy, gamma rays are used for killing or treating certain types of cancers. Gamma rays are also used for detecting brain and heart abnormalities.
These waves share some common properties. They are all transverse waves and consist of an oscillating electric and magnetic field. They travel at the same speed in vacuum.
Antennas are used in emitting and receiving radio waves. Antennas are made up of conductors such as metal rod resonators.
Radio waves are majorly used for transmitting information across distances. They find their application in radio communication systems such as radio broadcasting, television, communication satellites and wireless networking. Radio waves carry information across space. They are received by an antenna. The information in the radio waves is extracted by demodulation at the receiver end. Radio waves also find their application in Global Positioning System and navigational beacons. They are used for remote control and industrial heating as well.
Frequency range: 3 KHz - 3 × 102 GHz
Microwaves are capable of penetrating into materials, and end up depositing energy below the surface. Hence, they are used for heating food in microwave ovens, and are also widely used for industrial heating. They also find their use in radar systems, satellite communication, and wireless networking (Example: Wi-Fi).
Frequency range: 1 GHz - 103 GHz
Infrared radiations can be divided into three, namely the far-infrared, mid-infrared, and the near-infrared. Warm bodies tend to emit infrared waves. They are widely used in alarm systems, remote control and imaging applications.
Frequency range: 3×102 GHz - 4×102 THz
Human eye can detect electromagnetic radiation with a wavelength between 380 nm and 760nm, this is perceived as visible light. The light which excites the human visual system constitutes only a very small portion of the electromagnetic spectrum. A rainbow symbolizes the visible part of the electromagnetic spectrum.
Frequency range: 4×102 THz - 7×102 THz
Ultraviolet rays are very helpful in the study of celestial bodies. Sun releases UV radiation. Extremely short wavelength UV radiations can prove fatal for living organisms as well. But thanks to the ozone layer, it absorbs most of the sun’s harmful UV radiations.
Frequency range: 7.5×1014 Hz - 3×1016 Hz
X-rays interact with matter by means of compton effect. They can be used to see through objects. One of their major uses is in radiography (diagnostic x-ray imaging). X-rays play a significant role in high energy physics.
In the field of astronomy, the accretion disks around neutron stars and black holes emit X-rays, helping us to study these phenomena. X-ray telescopes are placed outside the Earth’s atmosphere to see astronomical X-rays.
Frequency range: 1016 Hz - 1020 Hz
Gamma rays were discovered by Paul Ulrich Villard in the year 1900. They find their application in the nuclear industry, food industry and also in the field of medicine (PET scan). Their wavelength can be measured with high accuracy.
Frequency range: 3×1018 Hz - 5×1022 Hz
Check your knowledge
Answer) Radio waves, microwaves, infrared waves, visible light, ultraviolet, x-rays, and gamma rays.
Answer) The Ozone layer.
Answer) Paul Ulrich Villard