Can I study 12th class chapter electromagnetic waves without studying chapter electromagnetic induction & alternating current?
Well, before moving on to the chapter on electromagnetic waves, make sure to attempt to cover electromagnetic induction and alternating current. You must first grasp the fundamental ideas. Skipping through fundamental principles can have catastrophic effects.
Electromagnetic radiation (EMR) is a kind of physics that comprises of electromagnetic (EM) field waves that propagate over space and convey electromagnetic radiant energy. Electromagnetic radiation is made up of synchronized oscillations of magnetic and electric fields, that are termed as electromagnetic waves. The periodic change of an electric or magnetic field creates electromagnetic radiation or electromagnetic waves. Different wavelengths of the electromagnetic spectrum are formed based on how this periodic shift happens as well as the power generated.Electromagnetic waves travel at the speed of light in a vacuum, typically abbreviated as c. The oscillations of the two fields generate a transverse wave in homogeneous, isotropic medium because they are perpendicular to each other and to the direction of energy and wave propagation. A sphere is the wavefront of electromagnetic waves emitted from a point source. The position of an electromagnetic wave in the electromagnetic spectrum may be determined by its frequency of oscillation or wavelength. Different names are given to electromagnetic waves of various frequency due to the general differences in their sources and effects on matter. In ascending frequency and decreasing wavelength order, they include radio waves, microwaves, IR, VIS, UV, X-rays, and gamma rays, among others.
Electromagnetic waves
Electrically charged particles experiencing acceleration create electromagnetic waves, which can then interact with other charged particles and exert force on them. It is possible for EM waves to transfer momentum, energy, and angular momentum from their source to any object they interacted with.Because they have moved far enough away from the moving charges that formed them, electromagnetic radiation is linked with EM waves that are free to propagate without the influence of the moving charges that produced them. As a result, EMR is also known as the far field. The term “near field” refers to electromagnetic fields that are close to the charges and currents that directly created them, such as electromagnetic induction and electrostatic induction.
Quantum Theory
According to quantum theory, EMR is made up of photons, which are uncharged elementary particles with zero rest mass and are the quanta of the electromagnetic field, which are responsible for all electromagnetic interactions. Quantum electrodynamics is the theory that describes how electromagnetic radiation interacts with matter at the atomic level.The transport of electrons to lower energy states in an atom and black-body radiation are examples of quantum processes that contribute to EMR. A photon’s energy may be quantized, as well as the energy of higher frequency photons is greater. Planck’s equation E = hf describes this relationship, where E is the energy per photon, f is the photon’s frequency, and h is Planck’s constant. For example, a single gamma ray photon might have 100,000 times the energy of a single visible light photon.
Effects of EMR
The effects of EMR on chemical compounds and biological organisms are determined by the strength and frequency of the radiation. Because the photons in visible or lower frequency EMR do not have enough energy to ionise atoms or molecules or break chemical bonds, it is referred to as non-ionizing radiation. Heating effects from the combined energy transfer of numerous photons induce the impact of these radiations on chemical processes and biological tissue. Ionizing radiation, on the other hand, is defined as high-frequency ultraviolet, X-rays, and gamma rays, since individual photons of such high frequency have enough energy to ionise molecules or break chemical bonds. These rays have the potential to catalyse chemical reactions and harm living cells in ways that aren’t possible with basic heating, posing a health risk.
Radio, infrared (IR), microwave, visible (VIS), ultraviolet (UV), X-rays, and gamma rays are the wavelength classifications for electromagnetic radiation. Fourier analysis may be used to convert any electromagnetic waves into sinusoidal monochromatic waves, which can then be categorised into these EMR spectrum areas.
Learn how to solve the question below:
Find:
(a) the impedance of the circuit
(b) phase difference between the voltage across the source and current
(c) the power dissipated in the circuit and
(d) the power factors
Waveform
The waveform is most advantageously represented as random for specific types of EM waves, and then spectrum analysis must be done using somewhat different mathematical procedures applicable to random or stochastic processes. Individual frequency components are represented in terms of their power content in such circumstances, and phase information is lost. The power spectral density of the random process is a representation like this. Random electromagnetic radiation needing this sort of study may be found in the interiors of stars, as well as in some other highly wideband kinds of radiation like the electromagnetic vacuum’s Zero-point wave field.
The behaviour of electromagnetic radiation and its interaction with matter is frequency dependent, and varies qualitatively as frequency changes. Higher frequencies have shorter wavelengths and are related with higher-energy photons, while lower frequencies have longer wavelengths. At either end of the spectrum, there is no known fundamental limit to these wavelengths or energies, while photons with energies close to or above the Planck energy will require new physical theories to describe.