Physics Terminology : Essential Physics Terminology Part-1. 200 Terms (from A to E)

Physics Terminology : Essential Physics Terminology Part-1

Physics Terminology

Physics terminology refers to the specialised words and expressions used to describe physical concepts, phenomena, measurements, processes, and laws. These terms provide a precise and standardised language that scientists, students, engineers and researchers use to communicate ideas clearly and accurately.

Because physics deals with the fundamental behaviour of matter, energy, space and time, its vocabulary needs to be exact. Terms such as force, momentum, entropy, frequency, wavelength, resistance, and quantum state each carry specific scientific meanings that differ from their everyday usage. Misunderstanding or misusing these terms can lead to incorrect conclusions or confusion.

Physics terminology is often derived from Latin, Greek, or the names of scientists who made significant contributions-for example, joule, newton, tesla, and curie. Many terms are also linked to mathematical representations, units of measurement or experimental observations.

A good grasp of physics terms helps in:

• Understanding textbooks, lectures and scientific papers
• Solving numerical and conceptual problems
• Describing experiments and results accurately
• Connecting theories with real-world applications
• Communicating clearly in academic, research or technical settings

Overall, physics terminology forms the foundation of effective learning and communication in the subject. Developing familiarity with these terms enables better comprehension of concepts and strengthens one’s ability to apply physics in practical and advanced contexts.

Physics Terminology : 200 Terms (from A to E)

Here are 200 Terms (from A to E) :

Physics Terminology (A)

• Acceleration– The rate at which the velocity of an object changes with time.
• Absorption– The process by which matter takes in energy from electromagnetic radiation or particles.
• Absolute Zero– The lowest possible temperature, 0 Kelvin, where molecular motion theoretically ceases.
• Alternating Current (AC)– An electric current that reverses direction periodically.
• Amplitude– The maximum displacement of a wave from its equilibrium position.
• Angular Momentum– The rotational equivalent of linear momentum, conserved in isolated systems.
• Angular Velocity– The rate of change of angular displacement with respect to time.
• Anode– The positive electrode in an electric device where oxidation occurs.
• Antimatter– Matter composed of antiparticles, which have opposite charge and quantum properties compared to ordinary particles.
• Archimedes’ Principle– States that a body immersed in a fluid experiences an upward force equal to the weight of the fluid displaced.
• Astrophysics– The branch of physics dealing with celestial bodies and the physical laws governing the universe.
• Atomic Mass– The mass of an atom, usually expressed in atomic mass units (amu).
• Atomic Number– The number of protons in the nucleus of an atom, defining its element.
• Attenuation– The reduction of signal strength or intensity of a wave as it travels through a medium.
• Avogadro’s Number– The number of particles in one mole of substance, approximately 022×10236.022×1023.

Physics Terminology (B)

• Background Radiation– Natural radiation present in the environment from cosmic rays and terrestrial sources.
• Balanced Force– Forces acting on a body that are equal in magnitude and opposite in direction, resulting in no movement.
• Band Gap– The energy difference between the valence band and conduction band in semiconductors.
• Bar Magnet– A permanent magnet in the shape of a bar that creates a magnetic field around it.
• Barometer– An instrument used to measure atmospheric pressure.
• Baryon– A subatomic particle, such as a proton or neutron, made of three quarks.
• Beam– A collection of particles or waves travelling together in a particular direction.
• Beta Particle– A high-energy electron or positron emitted during radioactive decay.
• Binding Energy– The energy required to split a nucleus into its individual protons and neutrons.
• Biophysics– The study of biological systems using the methods and principles of physics.
• Black Body– An idealised physical body that absorbs all incident electromagnetic radiation.
• Black Hole– A region in space where gravity is so strong that nothing, not even light, can escape.
• Bohr Model– A model of the atom in which electrons orbit the nucleus in defined energy levels.
• Boltzmann Constant– A physical constant that relates temperature to the average kinetic energy of particles.
• Bose-Einstein Condensate– A state of matter formed at near absolute zero, where particles occupy the same quantum state.
• Boundary Conditions– Constraints used to solve equations in physics, especially in wave and field problems.
• Boyle’s Law– A gas law stating that pressure is inversely proportional to volume at constant temperature.
• Bragg’s Law– Describes the angles at which X-rays are diffracted by crystal planes.
• Buoyancy– The upward force exerted on an object immersed in a fluid.

Physics Terminology (C)

• Capacitance– The ability of a system to store electric charge per unit potential difference.
• Capacitor– An electronic component that stores and releases electrical energy.
• Cathode– The negative electrode in an electric device where reduction occurs.
• Cathode Ray Tube (CRT)– A vacuum tube that uses electron beams to create images on a screen.
• Centrifugal Force– An apparent force that seems to push a rotating object outward from the centre of rotation.
• Centripetal Force– The force directed towards the centre of a circular path that keeps an object moving in a circle.
• Chain Reaction– A self-sustaining nuclear reaction in which the fission of one nucleus causes further fission.
• Charge– A fundamental property of matter that causes it to experience force in an electric or magnetic field.
• Cherenkov Radiation– Light emitted when a charged particle moves faster than the speed of light in a medium.
• Chromatic Aberration– Distortion in optical lenses caused by different wavelengths focusing at different points.
• Circuit– A closed path through which electric current flows.
• Clausius-Clapeyron Equation– Relates pressure and temperature changes during phase transitions.
• Coefficient of Friction– A measure of the resistance to motion between two contacting surfaces.
• Coherence– The fixed phase relationship between waves of the same frequency.
• Collision– An event in which two or more bodies exert forces on each other for a brief time.
• Commutator– A rotating electrical switch in motors that reverses current direction.
• Complex Number in Physics– A mathematical representation combining real and imaginary parts, useful in wave mechanics.
• Compressibility– A measure of how much a material can be compressed under pressure.
• Conduction– The transfer of heat or electricity through direct contact of particles.
• Conductor– A material that allows the easy flow of electric current.
• Conservation Laws– Fundamental principles stating that certain physical quantities remain constant in isolated systems.
• Conservation of Energy– States that energy cannot be created or destroyed, only transformed.
• Conservation of Momentum– States that the total momentum of a closed system remains constant.
• Constellation– A group of stars forming a recognised pattern in the night sky.
• Constructive Interference– Occurs when waves combine to produce a wave of greater amplitude.
• Control Rods– Devices used in nuclear reactors to absorb neutrons and regulate fission.
• Convection– The transfer of heat through the movement of fluids.
• Convex Lens– A lens that converges light rays to a focal point.
• Concave Lens– A lens that diverges light rays outward.
• Coulomb’s Law– Describes the electrostatic force between two charges as proportional to the product of charges and inversely proportional to the square of the distance between them.
• Critical Angle– The minimum angle of incidence for which total internal reflection occurs.
• Critical Temperature– The highest temperature at which a substance can exist as a liquid regardless of pressure.
• Cross-Section (Physics)– A measure of the probability of interaction between particles.
• Crystal Lattice– A regular arrangement of atoms or ions in a solid.
• Curie Point– The temperature at which a ferromagnetic material becomes paramagnetic.
• Current– The rate of flow of electric charge through a conductor.
• Cyclotron– A particle accelerator that uses magnetic and electric fields to accelerate charged particles in a spiral path.

Physics Terminology (D)

• Dark Energy– A hypothetical form of energy thought to drive the accelerated expansion of the universe.
• Dark Matter– Invisible matter that does not emit light but exerts gravitational effects on visible objects.
• Decay Constant– A quantity that represents the rate at which unstable nuclei undergo radioactive decay.
• De Broglie Wavelength– The wavelength associated with a particle, showing matter can behave like waves.
• Debye Model– A theory describing the heat capacity of solids at low temperatures.
• Decibel (dB)– A logarithmic unit used to measure sound intensity or signal strength.
• Deflection– The change in direction of a particle or wave due to an external force or field.
• Degenerate Matter– A highly dense state of matter formed when particles are packed extremely closely, as in white dwarfs.
• Density– The mass per unit volume of a substance.
• Deposition– The phase change directly from gas to solid without becoming liquid.
• Destructive Interference– When two waves combine to produce a lower or zero resultant amplitude.
• Detector– A device that identifies or measures particles, radiation, or physical properties.
• Dewar Flask– An insulated container used to store liquefied gases at very low temperatures.
• Dielectric Constant– A measure of a material’s ability to store electrical energy in an electric field.
• Diffraction– The bending and spreading of waves when they pass through a narrow opening or around obstacles.
• Diffusion– The movement of particles from a region of high concentration to low concentration.
• Diode– An electronic component that allows current to flow in only one direction.
• Dipole– A pair of equal and opposite charges or magnetic poles separated by a small distance.
• Direct Current (DC)– An electric current that flows steadily in one direction.
• Displacement– The shortest distance and direction from an object’s initial to final position.
• Dispersion– The separation of light into its component colours due to varying refractive indices.
• Distance– The total path length travelled by an object, without regard to direction.
• Distortion– Alteration of the original shape or characteristics of a signal or waveform.
• Doppler Effect– The change in the observed frequency of a wave due to relative motion between source and observer.
• Double Refraction– The splitting of a light beam into two rays when it passes through certain crystals.
• Drift Velocity– The average velocity of charge carriers in a conductor due to an electric field.
• Dual Nature of Matter– The concept that particles, such as electrons, exhibit both wave and particle behaviours.
• Dynamics– The branch of mechanics that studies forces and the motion they cause.
• Dyne– A unit of force in the CGS system equal to 10−510−5
• Dynamo– A device that converts mechanical energy into electrical energy using electromagnetic induction.
• Deuterium– An isotope of hydrogen containing one proton and one neutron in its nucleus.
• Diffusion Current– The movement of charge carriers from a region of high concentration to low concentration.
• Domain (Magnetic)– A region in a magnetic material where all the atomic magnetic moments are aligned.
• Dosimeter– A device used to measure an individual’s exposure to ionising radiation.
• Ductility– A material’s ability to be stretched into wires without breaking.
• Degree of Freedom– The number of independent ways in which a system can move or possess energy.
• Dalton’s Law– States that the total pressure of a gas mixture is the sum of the partial pressures of each gas.
• Diffusion Coefficient– A parameter representing the rate at which particles spread out in a medium.
• Drag Force– The resistive force acting opposite to the motion of an object moving through a fluid.
• Desalination by Distillation– The process of removing salt from water using heat and phase change.
• Diamagnetism– A weak form of magnetism in which materials create an opposing field when exposed to magnets.
• Dielectric Breakdown– When an insulating material becomes conductive under high voltage.
• Disintegration Energy– The energy released when a nucleus breaks into smaller fragments.
• Debye Temperature– A characteristic temperature related to a solid’s vibrational properties.
• Density of States– The number of available energy levels per interval of energy in a system.
• Drude Model– A classical model explaining the transport of electrons in metals.
• Dosage (Radiation)– The amount of radiation energy absorbed per unit mass of material.
• Dynamic Equilibrium– A state where opposing processes occur at the same rate in a system.
• Damping– The reduction in the amplitude of oscillations due to energy loss.
• Deformation– The change in the shape of a body due to applied stress.
• Diffraction Grating– An optical device with multiple slits used to disperse light into spectra.
• Displacement Current– A changing electric field that produces effects similar to electric current in Maxwell’s equations.
• Decoherence– The loss of quantum behaviour due to interaction with the environment.
• Detector Efficiency– A measure of how effectively a detector identifies incident radiation or particles.

Physics Terminology (E)

• Earthquake Waves– Seismic waves produced by the movement of tectonic plates within the Earth.
• Eddy Currents– Circular electric currents induced in conductors by changing magnetic fields.
• Efficiency– The ratio of useful output energy to input energy in a system.
• Elastic Collision– A collision where both momentum and kinetic energy are conserved.
• Elasticity– The ability of a material to return to its original shape after deformation.
• Electric Charge– A fundamental property of matter causing it to experience electromagnetic force.
• Electric Circuit– A closed path allowing electric current to flow.
• Electric Current– The rate at which electric charge flows through a conductor.
• Electric Field– The region around a charged object where other charges experience force.
• Electric Flux– The measure of the electric field passing through a surface.
• Electrical Resistance– The opposition faced by electric current in a conductor.
• Electromagnet– A magnet created by passing electric current through a coil of wire.
• Electromagnetic Induction– The production of an electromotive force due to a changing magnetic field.
• Electromagnetic Spectrum– The full range of electromagnetic waves from radio to gamma rays.
• Electron– A negatively charged subatomic particle found in atoms.
• Electron Affinity– The energy change when an atom gains an electron.
• Electron Capture– A process where a proton absorbs an electron and converts into a neutron.
• Electron Configuration– The arrangement of electrons around the nucleus of an atom.
• Electron Degeneracy Pressure– A quantum mechanical pressure preventing collapse of dense matter.
• Electron Microscope– An instrument that uses electrons to produce high-resolution images.
• Electronic Transition– The movement of an electron between energy levels in an atom.
• Element (Chemical)– A pure substance made of only one type of atom.
• Elevation– The height of an object above a reference level, often sea level.
• Emission Spectrum– The spectrum of light emitted by atoms or molecules when energised.
• Emitter– The electrode in a transistor that emits charge carriers.
• Empirical Formula– The simplest ratio of elements in a compound.
• Endothermic Process– A process that absorbs heat from the surroundings.
• Energy– The capacity to do work or cause physical change.
• Energy Band– Allowed ranges of energy levels in a solid, especially in semiconductors.
• Energy Density– The amount of energy stored in a system per unit volume.
• Energy Level– The specific energies that electrons in an atom can occupy.
• Engine Efficiency– The percentage of fuel energy converted into useful work.
• Enthalpy– The total heat content of a system at constant pressure.
• Entropy– A measure of disorder or randomness in a system.
• Enzyme Physics– The study of physical principles governing enzyme action and molecular interactions.
• Equilibrium– A state where opposing forces or processes are balanced.
• Equilibrium Position– The central point around which oscillatory motion occurs.
• Equipotential Surface– A surface where every point has the same electric potential.
• Equivalence Principle– The idea that gravitational and inertial mass are identical.
• Escapement Mechanism– A device that controls the motion of mechanical clocks.
• Escape Velocity– The minimum speed required to leave a planet’s gravitational field.
• Ethanol Thermometer– A device that uses ethanol as the working fluid to measure temperature.
• Eutectic Point– The temperature and composition at which a mixture melts completely.
• Evaporation– The process where a liquid changes into a gas below its boiling point.
• Excitation Energy– The energy required to raise an electron to a higher energy level.
• Exciton– A bound state of an electron and a hole in a semiconductor.
• Exergonic Reaction– A reaction that releases energy to the surroundings.
• Exothermic Process– A process that releases heat energy to the environment.
• Expansion (Thermal)– The increase in size of a material due to heating.
• Extensive Property– A physical property that depends on the amount of matter present.
• External Force– A force applied to a system from outside its boundary.
• Extreme Ultraviolet– A region of the electromagnetic spectrum with very short UV wavelengths.
• Eyepiece– The lens in an optical instrument through which the observer looks.
• Earth Inductor– A device used to measure the strength of Earth’s magnetic field.
• E=mc²– Einstein’s equation stating mass and energy are interchangeable.
• Electret– A material that retains a quasi-permanent electric charge.
• Electrolysis– The decomposition of a substance using electric current.
• Electrolyte– A substance that conducts electricity when dissolved or molten.
• Electromotive Force (EMF)– The energy provided per unit charge by a source.
• Electrostatics– The study of electric charges at rest.
• Elemental Particle– A fundamental particle with no substructure.
• Eliminative Cooling– Cooling resulting from evaporation of moisture.
• Emissivity– A material’s ability to emit thermal radiation.
• End Reflection– Reflection occurring at the boundary of a medium’s end.
• Enhancement Mode– A type of transistor operation where current flows only when voltage is applied.
• Equilateral Prism– A prism with all angles equal, used for dispersion of light.
• Erg– A unit of energy in the CGS system equal to 10−710−7
• Esterification Energy– The energy involved in forming esters from acids and alcohols.
• Ether Theory– A historical concept that light travelled through a medium called “aether.”
• Eutrophication Physics– Study of physical factors affecting oxygen levels in water bodies.
• Exponential Decay– A process where a quantity decreases at a rate proportional to its value.
• Extrinsic Semiconductor– A semiconductor doped with impurities to alter conductivity.
• Eye Accommodation– The process by which the eye adjusts focus at different distances.
• Earth’s Magnetic Field– The natural magnetic field generated by the Earth’s core.
• Ecliptic Plane– The plane in which Earth orbits the Sun. 

Conclusion 

Physics terminology is not just vocabulary – it is the backbone of understanding and communicating scientific ideas with clarity and precision. Each term represents a well-defined concept, law, measurement, or phenomenon, helping to eliminate ambiguity and foster accurate interpretation across education, research, and application.

From classical mechanics and thermodynamics to quantum theory and astrophysics, mastery of terminology allows learners and professionals to:

• Grasp complex ideas more easily
• Connect theory with real-world observations
• Interpret scientific data correctly
• Communicate findings with consistency and confidence
• Build a strong foundation for advanced study or research

In essence, physics terminology serves as the universal language of the physical sciences. Whether used in classrooms, laboratories, engineering fields, or space research, these terms empower individuals to explore, explain and expand our understanding of the universe.

Go to Essential Physics Terminology Part-2 (F to I)

Go to Essential Physics Terminology Part-3 (J to O)

Go to Essential Physics Terminology Part-4 (P to S)

Go to Essential Physics Terminology Part-5 (T to Z)

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