Electromagnetic Waves
Electromagnetic Waves - Related Videos
01:30
Electromagnetic Waves
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2023
James Clerk Maxwell formulated a single theory combining all the electric and magnetic effects scientists knew during that time, calling the phenomena his theory predicted “Electromagnetic waves”. He brought together all the work that had been done by brilliant physicists such as Oersted, Coulomb, Gauss, and Faraday and added his own insights to develop the overarching theory of electromagnetism. Maxwell’s equations, combined with the Lorentz force law, encompass all the laws of electricity and...
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Plane Electromagnetic Waves I
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2023
The existence of combined electric and magnetic fields that propagate through space as electromagnetic (EM) waves is the most significant prediction of Maxwell's equations. As Maxwell's equations hold in free space, the predicted electromagnetic waves do not require a medium for their propagation. An EM wave comprises an electric field, defined as the force per charge on a stationary charge, and a magnetic field, which is the force per charge on a moving charge. The EM field is assumed to be a...
01:29
Plane Electromagnetic Waves II
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2023
Consider a plane wavefront traveling in position x-direction with a constant speed. This wavefront can be utilized to obtain the relationship between electric and magnetic fields with the help of Faraday's law. To apply Faraday's law, consider a rectangle of width a, as shown in the figure.1, whose area vector is in the positive z-direction. To solve the left-hand side integral in Faraday's law, integrate counterclockwise along the rectangle. The electric field is zero along one of the...
01:30
Electromagnetic Waves in Matter
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2023
Electromagnetic waves can travel in the vacuum as well as in matter. For example light, which is an electromagnetic wave, can travel through air, water, or glass. Consider the electromagnetic wave passing through a dielectric medium. In such a case, Maxwell's equations get modified. In Ampere's law, ε0 , the dielectric permittivity of free space is replaced with ε, the permittivity of dielectric. Also, the vacuum permeability μ0 is replaced by the permeability of the medium, μ. Furthermore, the...
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Standing Electromagnetic Waves
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2023
Electromagnetic waves can be reflected; the surface of a conductor or a dielectric can act as a reflector. As electric and magnetic fields obey the superposition principle, so do electromagnetic waves. The superposition of an incident wave and a reflected electromagnetic wave produces a standing wave analogous to the standing waves created on a stretched string. Suppose a sheet of a perfect conductor is placed in the yz-plane, and a linearly polarized electromagnetic wave traveling in the...
FAQs
Propagation depends on a continuous interaction between the two fields: a changing electric field generates a magnetic field, and a changing magnetic field generates an electric field. This mutual generation allows the disturbance to sustain itself as it moves rather than requiring a material medium at every point. The same mechanism explains why electromagnetic energy can cross empty space.
Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays belong to one spectrum, yet they are distinguished primarily by wavelength and frequency. This distinction gives researchers a systematic way to classify electromagnetic radiation and select the relevant part of the spectrum for a scientific or technological task. Comparing regions connects measurable wave properties with different uses.
Because electromagnetic waves can propagate through a vacuum, their transmission does not depend entirely on the presence of material between source and destination. They can also travel through matter, allowing physical systems to interact with and be examined by radiation. This dual ability is central to using electromagnetic waves for both space-spanning communication and measurements involving material systems.
Spectroscopy uses electromagnetic radiation to investigate matter and energy by examining how a physical system responds to different parts of the electromagnetic spectrum. The spectrum’s range, from radio waves through gamma rays, provides multiple wavelength and frequency regions for such investigations. This approach connects measurable wave properties with information about the system being studied, rather than treating all radiation as interchangeable.
Remote sensing and imaging use electromagnetic waves to obtain information about physical systems without limiting investigation to direct contact. Remote sensing is associated with observations made from a distance, while imaging helps represent or examine systems. Because the electromagnetic spectrum contains several wavelength and frequency regions, these applications can draw on its broad range.
Wireless transmission and medical imaging illustrate two different outcomes of electromagnetic energy. Transmission uses waves in communication, whereas imaging applies them to the examination of physical systems in a medical setting. Together, these uses show that electromagnetic waves are not limited to carrying signals: they can also support practical observations of matter and energy.