Electromagnetic Radiation - Wave Nature

What is Electromagnetic Radiation?

Electromagnetic radiation is a flow of energy in which electrical and magnetic fields vary simultaneously. Radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays and gamma rays are all electromagnetic radiations. Electromagnetic radiations travel in space and vacuum through oscillating electrical and magnetic fields generated by their particles. The theory of electromagnetic radiation was given by Scottish scientist Sir James Clerk Maxwell in the early 1870s. It was experimentally confirmed by German Physicist Heinrich Hertz. Maxwell suggested that when an electrically charged particle moves under acceleration that time alternating electrical and magnetic fields are produced which helps the particle in propagation. 

Electromagnetic waves show dual nature. It can act as a wave and a particle as well. Its wave nature is represented by its velocity, frequency and wavelength. 

Define Electromagnetic Spectrum 

Electromagnetic spectrum consists of various types of electromagnetic radiations which differ from one another in wavelength or frequency. Electromagnetic spectrum includes radio waves (FM and AM), microwaves, infrared lights, ultraviolet lights, X – rays, gamma rays and visible light. The spectrum of electromagnetic radiation is given below –

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As you can see in the above figure of the electromagnetic spectrum that as the wavelength of a radiation increases its frequency decreases. Although as its wavelength decreases, its energy increases. Different regions of the electromagnetic spectrum are identified by various names. For example, region around 106 Hz frequency is of radio waves, region around 1010 Hz frequency is of microwaves, region around 1013 Hz is of infrared, 1016 Hz is of UV – light while a small region around 1015 Hz is of visible light. Visible light is the only part which our eyes can see. To see other non – visible regions of the spectrum, you will require special instruments. 

Properties of Electromagnetic Waves 

Simple and general properties of electromagnetic radiations are given below –

  • Oscillating charged particles produce electric and magnetic fields. These oscillating electrical and magnetic fields are perpendicular to each other and to the direction of propagation of the wave. It is shown in the figure below –

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  • Electromagnetic waves do not require any medium. They can travel in vacuum or space.

  • As stated in the above section, electromagnetic waves are of many types and collectively they form electromagnetic spectrum. Different types of electromagnetic waves differ from one another in wavelength or frequency. 

  • To represent electromagnetic radiation, various kinds of units are used. 

  • Electromagnetic waves travel through the vacuum at a speed of 3 x 108 m/s. This is called speed of light.  

Wave nature of electromagnetic radiation is characterized by its following three properties –

  • Wavelength 

  • Frequency 

  • Velocity 

Wavelength – The distance of one full cycle of the oscillation is called wavelength or the distance between two adjacent crests or troughs of a wave is called the wavelength. It is represented by \[\lambda\]. 

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Frequency – The number of waves that pass a given point in one second is called frequency. It is represented by v. Its SI unit is Hertz which is represented as Hz. 

Velocity – The velocity of electromagnetic wave in vacuum is 3 × 108 m/s. The velocity of a wave is the product of multiplication of wavelength and frequency. It can be expressed as follows –

Velocity = \[\lambda v\]

Other characteristics of a wave are amplitude and period. We are giving a brief of these as well for your better understanding. 

Amplitude – Amplitude is represented in the above figure. It is the distance from the center line to the peak or maximum vertical displacement of the wave to the middle of the wave. It represents the height of the wave. Larger the amplitude, higher the energy. 

Period – It is the amount of time a wave takes to complete or travel one wavelength. It is represented by ‘T’ and measured in seconds. 

Relation Between Wavelength and Frequency 

Wavelength and frequency of a wave are inversely proportional. As the wavelength increases, frequency decreases and as the frequency increases wavelength decreases. As we know –

c = \[\lambda\]v

Where c = speed of light 

\[\lambda\] = wavelength 

v = frequency 

So, we can write –

\[\frac{c}{v}\] = \[\lambda\]

Thus, \[\lambda\] ∝ \[\frac{1}{v}\]

The relationship of frequency and wavelength has been shown above in the figure of the electromagnetic spectrum as well. 

Relation Between Frequency and Energy

As the frequency increases, energy also increases. Thus, frequency and energy are directly proportional. It can be expressed as –

E = hv

Where E = energy 

h = Plank’s constant which is equal to 6.6 × 10⁻³⁴ J

v = frequency

The relationship of frequency and energy has been shown above in the figure of the electromagnetic spectrum as well. 

This ends our coverage on the topic “Electromagnetic Radiation: Wave Nature”. We hope you enjoyed learning and were able to grasp the concepts. We hope after reading this article you will be able to solve problems based on the topic. If you are looking for solutions of NCERT Textbook problems based on this topic, then log on to Vedantu website or download Vedantu Learning App. By doing so, you will be able to access free PDFs of NCERT Solutions as well as Revision notes, Mock Tests and much more.