Author: Tru Physics
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Electromagnetic Interference
Introduction Electromagnetic interference (EMI), also referred to as radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit via electromagnetic radiation or induction. EMI can cause a range of problems, from minor annoyances like a noisy radio signal, to significant malfunctions in critical…
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Elasticity
Introduction Elasticity is a fundamental concept in physics that describes how a material returns to its original form after being deformed by an external force. This property is crucial in a wide range of fields, including engineering, materials science, and earth science. Hooke’s Law Hooke’s Law is the basic principle behind elasticity, and it states…
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Elastic Collisions
Introduction In physics, an elastic collision is an encounter between two bodies in which the total kinetic energy of the two bodies remains the same. In an idealized elastic collision, there is no net conversion of kinetic energy into other forms such as heat, noise, or potential energy. Fundamental Equations In one-dimensional elastic collisions, the…
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Einstein Field Equations
Introduction The Einstein field equations (EFE) are the cornerstone of Einstein’s theory of general relativity. They describe the fundamental interaction of gravitation as a result of spacetime being curved by matter and energy. They were first published by Einstein in 1915. The Equation The Einstein field equations can be written as: Here is the Einstein…
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Doppler Effect
Introduction The Doppler Effect is a change in frequency or wavelength of a wave in relation to an observer who is moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who proposed it in 1842. Basic Formulas The Doppler Effect can be described by the following formulas. For waves,…
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Dispersion Relation
Introduction A dispersion relation describes how the phase speed or group speed of a wave depends on its wavelength, or equivalently, how the energy of a particle depends on its momentum. The term “dispersion” refers to the phenomenon where the speed of a wave depends on its frequency. Basic Form of the Dispersion Relation In…
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Dirac Equation
Introduction The Dirac equation is a relativistic wave equation derived by British physicist Paul Dirac in 1928. It provides a description of elementary spin-1/2 particles, such as electrons, consistent with both quantum mechanics and the theory of special relativity. The Equation The Dirac equation in natural units () is written as: where is the wave…
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Diffraction
Introduction Diffraction is a wave phenomenon that occurs when a wave encounters an obstacle or a slit that is comparable in size to its wavelength. It is characterized by the bending and spreading out of waves past the obstacle or through the slit. The Principle of Diffraction Diffraction is a result of the wave nature…
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Decay Chains
Introduction A decay chain, also known as a radioactive decay series or a radioactive cascade, is a sequence of radioactive decays of different radioactive isotopes, each decaying into a “daughter” isotope, which then decays into another, and so on until a stable isotope is reached. Types of Decay Three primary types of decay can occur…
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Gamma Decay
Introduction Gamma decay is a type of radioactive decay where an excited nucleus emits a gamma ray to reach a lower energy state. Unlike alpha and beta decay, gamma decay does not change the number of protons or neutrons in the nucleus, thus, the parent and daughter isotopes are the same. Gamma Rays Gamma rays…