We know that an static charge produces an electric field around it. Again, when a charge is in motion, it produces a magnetic field around it. But do you know how do electromagnetic waves produce? An accelerating charge produces electromagnetic waves where both the electric field and magnetic field propagates together. This is called an electromagnetic field. The electric and magnetic energy flows in an electromagnetic field in the form of electromagnetic wave. In this article, we are going to explain the different types of electromagnetic waves in physics, their properties, examples and uses.
Contents in this article:
- What is electromagnetic wave?
- Origin of electromagnetic wave
- Properties of electromagnetic wave
- Types of electromagnetic waves in physics
- Is light an electromagnetic wave?
- Spectrum of electromagnetic wave
- use of electromagnetic waves
Definition of Electromagnetic wave in Physics
Time-varying electric field produces a magnetic field. Similarly, a varying magnetic field can produce an electric field. If varying electric field and magnetic field exist in a place, they flow together in the form of a wave in every directions around that place. This wave is called an electromagnetic wave.
The term electromagnetic arises from the terms electric field and magnetic field. Electromagnetic wave consists of both the electric and magnetic field. The resultant field where the electromagnetic wave propagates is known as the electromagnetic field.
Origin of Electromagnetic wave
The origin of Electromagnetic wave is the oscillating or accelerating charge. When an electric charge oscillates, a varying electric field arises. This varying electric field produces a varying magnetic field. As a result, an Electromagnetic wave develops.
Properties of Electromagnetic wave
The properties of electromagnetic waves are as following-
- Electromagnetic wave consists of both electric and magnetic field in it.
- Electric field, magnetic field and the direction of propagation of wave are mutually perpendicular to each other. Thus, electromagnetic wave is a transverse wave.
- The equations for electric field and magnetic field are as E = E0 sin(wt-kx) and B = B0 sin(wt-kx). Where, the wave is propagating along +x direction. If E-field is varying along the y-axis then the B-field will vary along the z-axis as they are mutually perpendicular.
- In electromagnetic wave the magnitude of electric field is c times the magnitude of magnetic field. Here c is the speed of light in free space which is equal to 3×108 m/s.
- The phase difference between the electric field and magnetic field in an electromagnetic wave is zero. That means they are in-phase.
- The speed of an electromagnetic wave in the free space is the same as the speed of light in the free space (3×108 m/s).
Examples of electromagnetic waves in physics
Seven electromagnetic waves are seen in the spectrum of electromagnetic wave. These are –
- Radio wave
- Infrared wave
- Visible rays
- Ultraviolet (UV) rays
- Gamma rays
I’ve discussed all these waves below.
Is the light an electromagnetic wave?
Yes, Light is an electromagnetic wave. Its energy flows in the form of a Transverse electromagnetic wave. Light has all the properties of electromagnetic wave as discussed above.
Read the article on light energy and its properties.
Different types of electromagnetic waves and their uses
In the spectrum of electromagnetic wave one can observe seven waves of different wavelengths and frequencies. They have different sources and different uses. The list of electromagnetic waves with their uses are given in below.
If an accelerating charge moves through a conductor, radio wave produces. This type of wave has wavelength in the range of 10000 metre to 0.1 metre. Radio wave used in Radio, Mobile phones, TVs etc. Radio wave also helps in satellite communications.
Microwave produces from different electronic gadgets. The wavelength range for Microwaves is from 0.3 metre to 10-4 metre. Microwave used in Micro-oven, RADAR system.
Vibration of molecules of matter at room temperature generates Infrared light. Wavelength range for Infrared light is from 10-3 metre to 4×10-7 metre. Infrared light has wide use in medical field and photography.
When electron jumps from higher orbit to lower orbit of an atom, it releases the energy in the form of photons or light. This is nothing but the visible light. Visible light has wavelength range from 4×10-7 meter to 7×10-7 meter. Human eyes can see the in this wavelength range of light.
Ultraviolet rays (UV rays)
The main source of UV rays is the Sun. Ultraviolet rays have the wavelength range from 7×10-7 metre to 10-10 metre. UV rays cure skin disease. But high intensity UV rays causes the skin cancer. Ozon layer protects us from high intensity UV rays coming from the sun.
X-rays can be produced by colliding a target atom by a highly energetic electron. The wavelength range for X-rays id from 0.01 angstrom to 10 angstrom. X-rays have wide uses in medical field, in paper cutting, as a barcode reader etc.
Gamma rays are produced from radioactivity. It has smallest wavelength and higher frequency. Therefore, the energy of gamma rays is much higher than other electromagnetic waves. Gamma rays have the wavelength smaller than one angstrom.
Uses of Electromagnetic waves
Electromagnetic waves have wide uses in communication system. In TV, radio, RADAR, Satellites etc. all the signals are transferred in the form of electromagnetic waves. Electromagnetic waves have also the applications in medical science.
Some useful questions
1. What electromagnetic wave has highest frequency?
Answer: Gamma ray. It has highest frequency and smallest wavelength.
2. What electromagnetic wave has the shortest wavelength?
Answer: Gamma ray. It has shortest or smallest wavelength and highest frequency.
3. What electromagnetic wave travels fastest?
Answer: All the electromagnetic waves have the same velocity of the speed of light. So, all electromagnetic waves move with the same speed.
This is all from the article on different types of electromagnetic waves in physics and their uses and properties. If you have any doubts you can ask in the comment section.
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