Electromagnetic Radiation - Wave Nature

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 Radiation interferes with electrical and magnetic field travel at light speeds (2.998 × 10⁸m / s). It does not contain weight or charge but travels through a series of dynamic energy packets called photons, or quanta. Examples of EM rays include radio waves and microwaves, as well as infrared, ultraviolet, gamma, and x-rays. Other EM radiation sources include celestial sources (e.g., sun and stars), radioactive elements, and manufactured devices. EM reflects the dual wave and particle nature. Electromagnetic Radiation travels in the direction of waves at a constant rate. EM wave characteristics are found in the relationship of speed to wavelength (straight line distance of one cycle) and frequency (cycles per second, or hertz, Hz), expressed in the formula.

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. 

Formula

c = λv

when c = velocity, λ = wavelength, and v = frequency.

Because the speed is constant, any increase in frequency leads to a continuous decrease in wavelength. Therefore, the wavelength and frequency are proportional. All EM rays are collected by wavelengths into the electromagnetic spectrum. The nature of EM particles is reflected in the interaction of ionizing photons with matter. The amount of energy (E) found in a photon is equal to its frequency (ν) the constant times of Plack (h):

E = nհ

Photon power is directly proportional to the photon frequency. Photon power is measured in eV or keV (kilo-electron volts). The power of the x-ray diagnostic range is 40 to 150keV. Gamma rays, x-rays, and other ultraviolet rays are strong enough (> 10keV) to induce ionization. The power of EM radiation determines its usefulness in diagnostic thinking. Due to its very short length, gamma rays and x-rays can penetrate large parts of the body. Gamma rays are used in radionuclide images. X-rays are used for blank film and computed tomography (CT) imaging. Visual light is used to view and interpret images. Magnetic resonance imaging (MRI) uses EM radio frequency radiation as a means of transmission

Define Electromagnetic Spectrum 

Electromagnetic spectrum consists of various types of Electromagnetic radiation 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, 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, the 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 the 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 the 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 λ.

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 an 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 = λv

Other characteristics of a wave are amplitude and period. We are giving a brief summary 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, the 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 = λ

Where c = speed of light 

λ = wavelength

 v = frequency

 So, we can write 

\[\frac{1}{v}\]= λ

Thus, λ ∝\[\frac{1}{v}\]

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 to NCERT Textbook problems based on this topic, then log on to the Vedantu website or download the 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.

Types of EMF Exposure

Radiation is present in the so-called electromagnetic spectrum. These rays range from high intensity (so-called high-frequency) on one side of the spectrum, to very low (or low-frequency) intensity on the other side.

Examples of High-Energy Radiation include:

• x-rays

• Gamma rays

• Some high-intensity ultraviolet (UV) rays

These are ionizing radiation, which means that these forces can affect atomic-level cells by releasing an electron atom, or "ionizing" them. Ionizing radiation can damage the DNA and cells of the body, which in turn may contribute to genetic mutations and cancer. On the other side of the spectrum are very low-frequency (ELF) rays. This is a type of non-ionizing radiation. It can move atoms in the body or cause them to vibrate, but most researchers agree that it is not enough to damage DNA or cells.Among the ELF rays and the strongest rays in the spectrum there are other types of non-ionizing radiation, such as:

• Radiofrequency (RF) radiation.

• Visible light

• Infrared

Electric and magnetic fields join as one field in many types of radiation. The result is called the electromagnetic field (EMF).

In Short, Here are Two Types of EMF Exposure:

1. High-frequency EMFs. This is a type of ionizing radiation. Scientific literature acknowledges that excessive exposure can damage the DNA or cells of a reliable source. Medical devices such as X-ray imaging and CT scans produce low levels of this radiation. Other sources include gamma rays from radiation and UV rays from sunburn or sun beds.

2. Low- to mid-frequency EMFs. This is a type of ionizing radiation. Gentle and thought to be harmless to humAns: Household appliances such as microwave ovens, cell phones, hair dryers, and washing machines, as well as power cords and MRIs, emit this type of radiation. This category of EMFs comprises very low EMF (EMF-EMFs) and radiofrequency EMFs (RF-EMFs).

Electromagnetic Radiation Features:

• Charging oscillating particles produce electrical and magnetic oscillating surfaces perpendicular to each other and both are perpendicular to the direction of wave propagation.

• Electric waves do not need a medium, that is, they can travel in an empty space as well.

• There are many types of Electromagnetic Radiation, which differ from one another in terms of wavelength or frequency. These whole electromagnetic rays form an electromagnetic spectrum. For example radio frequency region, microwave area, infrared area, ultraviolet region, visible area etc.

• Electromagnetic Radiation is detected based on various structures such as frequency, wavelength, time, etc.