Let’s start with the introduction of this article “What are electromagnetic waves?”. Read this article and solve every question related to electromagnetic waves.
What are Electromagnetic Waves?
Electromagnetic waves or EM waves are created as a result of vibrations of electric and magnetic fields. EM waves are waves that can travel through the vacuum of outer space (Unlike mechanical waves). These waves have synchronized oscillations of electric and magnetic fields perpendicular to each other and perpendicular to the direction of wave propagation.
The theory of EM waves was mainly discovered by Maxwell around 1864. According to Maxwell, an accelerated charge sets up a magnetic field in its neighborhood. Electromagnetic waves are also known as solutions of Maxwell’s equations.
Electromagnetic waves or EM waves do not require any material medium to travel; they can travel even in a vacuum. In a vacuum, all electromagnetic wave travels at the same speed. This same speed is the speed of light (3×108 m/s). The speed of light is the maximum possible speed, nothing can move faster than light.
Speed of light in Vacuum,
      c = 2.99792458 m/s
                 OR
        = 3×108 m/s
                 OR
        = 3 lakh Km/s
Electromagnetic Spectrum
It describes a wide range of different electromagnetic waves, also called EM waves. These are special types of waves that can travel without a medium. Unlike sound waves and water waves, electromagnetic waves don’t need any physical medium like fluid or a solid or air to propagate from one place to another. They can travel across the great vacuum of space with the speed of light that is 3 x 108 m/s.
EM waves have both an electric and magnetic component. They begin when charged particles, like electrons, vibrate due to the various forces acting on them. The vibration of charged particles results in an emission of energy known as electromagnetic radiation.
Electromagnetic waves propagate outward from the source. Just like regular transverse waves, the oscillations of EM waves are perpendicular to the direction of wave propagation.
Electromagnetic waves are complicated waves. In these waves, the electric component oscillates in one plane, while the magnetic component oscillates in a different plane.
Range of Electromagnetic Spectrum
The EM spectrum includes the range of all possible frequencies of electromagnetic waves. At one end of the spectrum are the waves with the lowest frequencies that is a radio wave, and the other end is the highest frequency waves that are gamma rays.
Electromagnetic waves can also be distinguished by their wavelength and frequency being inversely proportional to each other. One can view the electromagnetic spectrum not only in terms of increasing frequencies but also in terms of decreasing wavelengths. Since frequencies increase in the EM spectrum, wavelengths decrease.
 For example, if the radio waves have the largest wavelengths and lowest frequencies are present at one end while gamma rays with the smallest wavelength and the largest frequencies are present at the other end.
Properties of electromagnetic waves
Electromagnetic waves are composed of oscillating electric and magnetic fields at right angles to each other and both are perpendicular to the direction of propagation of the wave. Electromagnetic waves differ both in wavelength and frequency.
The source that produces them and methods of their detection are different, but they have the following common properties:
- They travel with a constant velocity of 3 x 108 m/s in a vacuum.
- They are not deflected by an electric or magnetic field.
- Their wavelength and frequency of the electromagnetic wave are related as c = vλ= ω/k.
- They are propagated by oscillating electric and magnetic fields oscillating at right angles to each other even in a vacuum.
- They are transverse waves that can show interference or diffraction and may be polarized.
The S.I. unit of frequency is Hertz and of wavelength is meter. Wavelength is expressed in the Angstrom unit or nanometre.
  1 Hertz = cycle/second
  1 Angstrom, Å = 10-10 m
  One Nanometre, 1 nm = 10-9m
Types of Electromagnetic Waves
 There are 7 types of Electromagnetic waves :
- Radio Wave
- Microwave
- Infrared Wave
- Visible Light
- Ultraviolet ray
- X-rays
- Gamma rays
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Radio Waves
- A radio wave is used in Radio Telescope.
- A radio wave is used in communication.
- It is used in a toy car remote.
- It is used in RADAR (Radio Detection and Ranging).
- The radio wave is used in the satellite.
- A radio wave is used in Radio (FM) and TV (DTH).
Microwave
It is observed by water molecules. These water molecules become heated to heat food.
- Microwave is used in Microwave Oven.
- Microwave is used in mobile, Wi-Fi, and Bluetooth.
Infrared Wave
Infrared waves are also called thermal radiation. Every heating object emits infrared waves.
- Infrared wave is used in TV Remote.
- Infrared wave is used in Night Vision Camera.
- It is used in thermal imaging.
Visible Light
- Newton determines visible light has Seven colors.
- Visible light is used in vision.
- Visible light is used in Photosynthesis.
- It is used in LASER (Light Amplification by Stimulated Emission of Radiation).
Ultraviolet Rays (UV Rays)
Ultraviolet Rays are very harmful to human skin but these rays are absorbed by the ozone layer. There are three types of UV Rays:
- UV-A: It is the least dangerous ultraviolet ray. Maximum UV-A arrived on earth and little amount was absorbed by the ozone layer.
- UV-B: It is more dangerous than UV-A and less dangerous than UV-C. UV-B causes skin cancer. Mostly UV-B is absorbed by the ozone layer.
- UV-C: It is the most dangerous ultraviolet ray. UV-C is completely absorbed by the ozone layer.
Uses of Ultraviolet Rays
- Ultraviolet Rays are used in forensics (distinguish between fake or original documents).
- Ultraviolet rays are used in water purification.
- It is used for making vitamin D.
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 X-rays
- X-rays are used in the Scanner and Security check.
- It is used in Radiography (Bone image).
- It is used to find cracks inside the precious stones.
- X-ray is used in the CAT scan (Computerized Automated Tomography Scan) and CT scans.
Gamma Rays
- Gamma rays are used in the treatment of cancer.
- It is used in Radiotherapy.
- It is used in PET scan (Positron Emission Tomography Scan).
- Gamma rays are used in Cobalt-60.
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