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How Electromagnetic Waves are Formed for JEE

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Last updated date: 23rd May 2024
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What is an Electromagnetic Wave?

Energy comes in different forms and can be transformed from one type to other. For example, water stored behind dams, and batteries are sources of stored or possible energy. On the other hand, objects that are in motion are the perfect example of kinetic energy. Protons and electrons, known as charged particles, generate an electromagnetic field when they move, producing electromagnetic waves. Electromagnetic waves play a crucial role in different communication technology and are also used in Radars. 


In simple words, electromagnetic waves are generated by the movement of different particles that are electrically charged. Scientists also call this Electromagnetic Radiation. These waves can move through air, space and other substances. Low-frequency waves are called electromagnetic waves, and waves at high frequency are known as electromagnetic radiation. 


Keep reading to know more about this and understand whether you can see electromagnetic waves


Different Types of Electromagnetic Waves

You will find two different types of electromagnetic waves based on their energy and frequency level. These are non-ionizing radiation and ionizing radiation. Speaking about ionizing radiation, these are very high-frequency electromagnetic waves, such as gamma rays or X-rays, and have sufficient photon energy to create ionization. 


On the other hand, NIR, Non-Ionizing Radiation, waves have a lower level of photons, and they can’t break the atomic bonds. They can produce different biological effects like inducing electrical current, heating, changing chemical reactions and more. 


Speaking about the uses of electromagnetic waves, they have a wide range of applications, like radio broadcasting, cooking, Wi-Fi, medical imaging and more. A perfect example of an electromagnetic wave is gamma rays. 


Characteristics of Electromagnetic Waves

Some of the major electromagnetic wave characteristics are: 

  • The magnetic field, as well as the electric field, will be perpendicular to the propagation’s direction.

  • Electromagnetic waves have two different fields, i.e., magnetic field and electric field.

  • Just like light waves, all types of electromagnetic waves have the characteristics of reflection.

  • The electromagnetic wave’s intensity will depend on the strength of the waves. The strength is measured in V/m volt/meter. 


Visible Light Wavelengths

Scientists have said that all electromagnetic radiation is light. Due to the unique electromagnetic wave properties, you can only see a tiny portion of electromagnetic radiation, and this is called visible light. Cone-shaped cells located in the eyes function as a receiver that captures the wavelengths of this narrow band of the spectrum. 


On the other hand, the spectrum’s other portions have electromagnetic wavelengths that are too small and too large and can be more energetic for your biological limitations. When the full spectrum of visible light moves across a prism, this divides the wavelength into different colours as every colour has a different wavelength. As per the experts, the wavelength of violet is very short, around 380 nanometers. On the other hand, the colour that has the longest wavelength is red, around 700 nanometers. 


Visible Light Spectrum

This is an electromagnetic wave segment that people can see. In simple words, this type of wavelength is known as visible light. As per the experts, people can detect electromagnetic wavelengths that range from 350 to 700 nanometers. So, light is an electromagnetic wave. 


In general, the visible section of an electromagnetic spectrum has the colours you see in rainbows, such as purple, blue, orange and red. It may be noted that these colours correspond to light’s different wavelengths. 


Examples of Electromagnetic Waves

  • Radio waves: Communication.

  • Infrared waves: Remote control as well as imaging applications.

  • Microwaves: Heating and data transmission.

  • Visible light: With this one can see the objects.

  • Ultraviolet Waves: Helpful in the study of galaxies.


Mathematical Representation of Electromagnetic Waves

A normal electromagnetic wave that is travelling in the X-direction can be represented using the following equation: 

$\begin{align}&E(x, t)=E_{\max } \cos (k x-\omega t+\Phi) \\&B(x, t)=B_{\max } \cos (k x-\omega t+\Phi)\\\end{align}$


In this formula, B stands for magnetic field vector and E stands for the electric field vector. Maxwell gave a fundamental idea about electromagnetic radiation. But Hertz confirmed that electromagnetic waves do exist. 


Maxwell’s Equation

Maxwell realized that light is an electromagnetic wave and this can be ascertained using the equation $c=\frac{1}{\sqrt{{{\varepsilon }_{\circ }}{{m}_{\circ }}}}=2.998\times {{10}^{8}}m/s$. Besides, this equation also proved that radio signals are also a type of electromagnetic waves. 


Understanding electromagnetic waves in detail are quite complicated. The magnetic and electric fields move a point in a direction that is perpendicular to the direction toward which the waves are travelling. For example, if the electromagnetic waves are moving in the z-direction and the oscillation of the electric field is in the x-direction, the magnetic field will oscillate in the y-direction. 


As electromagnetic waves are spread out in time and space, the density of energy can be a useful concept compared to the energy. The power of electromagnetic waves can be replaced with a useful concept of power density. As a wave’s energy content fills a volume of space, the density of energy can be defined as energy per volume. The equation is: 

$\eta =\frac{U}{V}$ 


Conclusion 

As electromagnetic waves are spread out in time and space, the density of energy can be a useful concept compared to the energy. The power of electromagnetic waves can be replaced with a useful concept of power density. You can have a better understanding of this after going through the information mentioned above.

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FAQs on How Electromagnetic Waves are Formed for JEE

1. Do electromagnetic waves have different wavelengths?

Whenever you listen to the radio, cook dinner or watch TV, you are actually using electromagnetic waves. Microwaves, television waves and radio waves are all various electromagnetic wave types. However, these waves will vary from one another in terms of wavelengths. Speaking about the wavelength of EM waves, this is the total distance between a wave crest to another. Waves will vary in size, from short gamma-rays size to long radio waves. Well, as per the experts, wavelengths are related to one another mathematically. 

2. What is the effect of electromagnetic fields with low frequency?

While radio and infrared light waves are converted to heat, a different electromagnetic field with a lower level of frequency can generate an electric current. That’s why experts utilize the term “induced current”.  There are small currents present in the body. Your nerves can send signals through electrical impulses. However, strong electric currents developed by different external sources can trigger nerves as well as muscles. Wondering whether your eye can detect wavelengths or not? Well, the human eye can easily detect 380 to 700 nanometers of electromagnetic wavelengths.