Nature of Electromagnetic Radiation

Introduction

Electromagnetic radiation is a term coined by famous scientist James Clerk Maxwell. He got the idea from the electric and magnetic properties possessed by the waves to propagate through space. Therefore the mechanism of emitting and absorbing substances by the visible lights and then reacting under various conditions while traveling into space is known as the theory of electromagnetic radiation.

Nature of electromagnetic radiation

It is a force experienced by a charge or multiple charges placed in an electric or magnetic field due to interaction with each other. In 1870, Clerk Maxwell gave this term to explain the interaction between charges when placed in an electric or magnetic field. According to him, electrical and magnetic fields are transmitted and produced by accelerating the electrically charged particles; these fields cross in the form of waves. These waves are defined as electromagnetic radiation. Light waves are also electromagnetic radiation.

Particle nature of electromagnetic radiation:

Electromagnetic radiations are packets of energies called photons. The energy associated with these photons is directly proportional to the wavelengths of electromagnetic radiation. This can be better depicted by the formula E=hf, where h is the Planck’s constant, E is the electromagnetic radiation and f stands for the wavelength of electromagnetic radiation. We will discuss Planck’s constant in detail, but let us know more about these electromagnetic radiations.

Electromagnetic radiation travels or propagates in a direction mainly oriented at right angles to the vibrations of both the electrical (E) and magnetic (B) oscillating field vectors, transporting energy from the radiation source to an undetermined final destination. The energy fields that are in oscillation are perpendicular to each other. Electric and field of force vectors do not seem to be only perpendicular to each other but are also perpendicular to the direction of wave propagation. By convention, the vectors representing the electrical and magnetic oscillating fields of electromagnetic waves are often omitted, although they are understood to exist.

Electromagnetic radiation and its properties

• Electromagnetic waves can travel in any medium.
• Electromagnetic radiations differ according to their wavelengths and frequencies. If you consider electromagnetic radiation as a whole, then it makes up the electromagnetic spectrum. For example, you can refer to the ultraviolet region, visible region, radiofrequency region, etc.
• Oscillating electric and magnetic fields are produced by the oscillating charged particles and they are perpendicular to each other. These charged particles are also perpendicular to the direction of wave propagation.
• Electromagnetic radiation is also specified depending on various properties. They are frequency, period, wavelengths, etc.

The formula of electromagnetic radiation

There is a formula to calculate the frequency and wavelength of electromagnetic radiations. The frequency of electromagnetic radiation is the number of waves that pass through a specific point in a second. The frequency of electromagnetic radiation is inversely proportional to its time period. The equation to relate frequency, wavelength and speed of light of electromagnetic radiation is as follows:

                C = ⋎ × λ

Where c is the speed of light, v is the frequency of the electromagnetic wave and lambda refers to the wavelength of the electromagnetic wave.

One can also determine electromagnetic radiation by other parameters like wave numbers. Simply put, wave numbers are the number of wavelengths per unit length; they are inversely proportional to the wavelength of electromagnetic radiation.

Dual behavior of electromagnetic radiation:

Since electromagnetic radiation exists both in wave nature and particulate nature it is known to show dual behavior. Let us know about it in detail. Electromagnetic radiation can be defined as spectrums that consist of infrared waves, ultraviolet radiation, microwaves and gamma rays. Energy transfer from one place to another can only become possible in two ways – through a wave and a particle.

To explain the photoelectric effect of electromagnetic radiation, you need to know that these consist of energy packets called photons, and they show the mechanism of diffraction and interference. From there it is clear that they possess a wave nature of electromagnetic radiation, and hence we can conclude that electromagnetic radiations are dual. 

Particle nature of electromagnetic radiation | Planck’s Quantum Theory:

Two points can explain this theory of electromagnetic radiation

1. The frequency of electromagnetic radiation is equal to the energy of absorbed or emitted radiation.
2. The atoms and molecules can emit and absorb a specific quantity of energy. The smallest amount of energy that can be absorbed or emitted is termed quantum.

According to Planck’s Quantum theory, 

 E= hv

Here, h is the Planck’s constant and its value is 6.626×10-34 J.s.

All electromagnetic radiation behaves according to wave theory or quantum theory. Electromagnetic waves consist of an electric field that varies in a direction perpendicular to the direction of propagation of the radiation and a magnetic field that is set at right angles to the electric field.

Both electric and magnetic fields travel at the speed of light. To understand remote sensing of electromagnetic radiation, you need to know the two main characteristics of electromagnetic radiation and their wavelength and frequency.

Conclusion:

Wavelength can be defined as the length associated with one wave cycle. It can be calculated by the distance between the successive wave crests. Wavelength is represented by the symbol lambda and is usually measured in meters.

Frequency can be defined as the number of wave cycles passing through a fixed point in one second; it is usually measured in hertz. The wavelength and frequency of electromagnetic radiations are inversely proportional to each other; if the wavelength is smaller, we will get the higher frequency, and if the wavelength is larger, we will get the smaller frequency. According to the dual nature of electromagnetic radiation, photons with the highest energies have the smallest wavelengths.

Antennas receive radio waves; they consist of conductors called metal rod resonators. They are used for radio broadcasting, television, radio communication, etc

Microwaves are waves having shorter wavelengths and are produced with magnetron and klystron tubes. They are used in radar, satellite communication, wireless networking, etc.

Infrared radiation is absorbed by the rotational modes and allows partial transmission; these can be used in astronomy.