Category: Index
-
Huygens’ Principle
Introduction Huygens’ Principle, named after the Dutch physicist Christiaan Huygens, is a fundamental concept in wave theory. It provides a comprehensive way to predict and understand how waves propagate in different media. Basic Concept Huygens’ Principle states that every point on a wavefront is itself the source of spherical wavelets, and the new wavefront is…
-
Hubble’s Law
Introduction Hubble’s Law is a fundamental principle in cosmology that describes the expansion of the universe. Named after the American astronomer Edwin Hubble, this law has had profound implications for our understanding of the cosmos. Basic Principle Hubble’s Law states that the recessional velocity of a galaxy (the speed at which it is moving away…
-
Hooke’s Law
Introduction Hooke’s Law describes the behavior of springs and other elastic materials. Named after the British physicist Robert Hooke, this law is a fundamental principle in the fields of mechanics and materials science. Basic Principle Hooke’s Law states that the force required to extend or compress a spring by some distance is proportional to that…
-
Hertz (unit)
Introduction The hertz (Hz) is the unit of frequency in the International System of Units (SI). It is named after the German physicist Heinrich Hertz, who made significant contributions to the study of electromagnetism. Definition One hertz is defined as one cycle per second. In mathematical terms, if a periodic event occurs once every second,…
-
Heat Capacity
Introduction Heat capacity, or thermal capacity, is a physical property of matter that describes the amount of heat energy required to change its temperature. It is an extensive property, meaning it depends on the amount of substance. Definitions Specific Heat Capacity The specific heat capacity () of a substance is the amount of heat required…
-
Heat
Introduction Heat is a form of energy that is transferred between systems or objects with different temperatures, flowing from the higher temperature system to the lower temperature one until equilibrium is reached. Heat and Thermodynamics In the context of thermodynamics, heat is described as the energy transferred across the boundary of a system due to…
-
Hafele-Keating Experiment
Introduction The Hafele-Keating experiment was a test of the theory of relativity. In October 1971, Joseph C. Hafele, a physicist, and Richard E. Keating, an astronomer, took four cesium-beam atomic clocks aboard commercial airliners. They flew twice around the world, first eastward, then westward, and compared the clocks against others that remained at the United…
-
Gravitational Waves
Introduction Gravitational waves are ripples in the fabric of spacetime caused by some of the most violent and energetic processes in the Universe. Albert Einstein predicted the existence of gravitational waves in 1916 in his general theory of relativity. Basics of Gravitational Waves Gravitational waves are distortions in spacetime that propagate as waves, emanating from…
-
Gravitational Lensing
Introduction Gravitational lensing is a phenomenon that occurs when a huge mass creates a gravitational field that distorts and focuses light passing near it. This effect was first predicted by Albert Einstein’s General Theory of Relativity and has since been confirmed by multiple observations. Basics of Gravitational Lensing According to General Relativity, a mass curves…
-
Gravitational Force
Introduction The gravitational force is a natural phenomenon by which all things with mass or energy—including planets, stars, galaxies, and even light—are brought toward one another. It is one of the four fundamental forces known in nature. Newton’s Law of Universal Gravitation In the 17th century, Sir Isaac Newton proposed his Law of Universal Gravitation,…