Physics Terminology: Essential Physics Terminology Part-2. More than 200 Terms (from F to I)

Physics Terminology: Essential Physics Terminology Part-2

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: More than 200 Terms (from F to I)

Here are more than 200 terms (from F to I)

Physics Terminology (F)

• Faraday Cage– An enclosure that blocks external electric fields using conductive material.
• Faraday Constant– The charge of one mole of electrons, approximately 96,485 coulombs.
• Faraday’s Law– States that a changing magnetic field induces an electromotive force in a circuit.
• Fermi Energy– The highest occupied energy level of electrons at absolute zero in a solid.
• Fermi Gas– A collection of non-interacting fermions, often used to model electrons in metals.
• Fermi Level– The energy level at which the probability of electron occupancy is 50%.
• Fermion– A particle with half-integer spin that follows the Pauli exclusion principle.
• Fertilisation Energy (Biophysics)– The minimal energy required for gamete fusion during reproduction.
• Fibre Optics– The transmission of light through thin glass or plastic fibres for communication.
• Field Force– A force that acts over a distance, such as gravitational or electric force.
• Field Lines– Imaginary lines representing the direction and strength of a field.
• Filament (Lamp)– A thin wire that glows when heated by electric current.
• Filled Orbitals– Electron shells containing the maximum number of electrons.
• Film Interference– Colour patterns formed due to reflection and interference in thin films.
• First Law of Thermodynamics– States that energy cannot be created or destroyed, only transferred or transformed.
• Fission– A nuclear process in which a heavy nucleus splits into smaller nuclei with energy release.
• Flame Photometry– A method to analyse elements using light emitted by flame-excited atoms.
• Flotation– The principle that objects float when their weight is less than the buoyant force.
• Flux– The rate of flow of energy, particles, or fields through a surface.
• Fluid Dynamics– The study of forces and motion in liquids and gases.
• Fluid Friction– Resistance encountered by objects moving through a liquid or gas.
• Fluorescence– The emission of light by a substance after absorbing radiation.
• Flux Density– The amount of a field (electric, magnetic, or particle) passing through a unit area.
• Focal Length– The distance between a lens or mirror and its focal point.
• Focal Point– The point where light rays converge or appear to diverge after passing through a lens or mirror.
• Forced Oscillation– Oscillation caused by an external periodic force.
• Force– A push or pull that can change the motion or shape of an object.
• Force Constant– A measure of the stiffness of a spring or bond.
• Fourier Series– A way of expressing periodic functions as sums of sines and cosines.
• Fractional Distillation– The separation of components in a mixture based on boiling points.
• Fraunhofer Lines– Dark lines in the solar spectrum caused by absorption in the Sun’s atmosphere.
• Free Body Diagram– A visual representation of the forces acting on an object.
• Free Electron– An electron not bound to an atom and able to move freely in a material.
• Free Fall– Motion of an object solely under gravitational force.
• Free Space– A vacuum with no matter, used as a physical reference environment.
• Frequency– The number of wave cycles passing a point per second.
• Friction– A force opposing motion between surfaces in contact.
• Frictional Heating– Heat produced due to resistance between moving surfaces.
• Frictionless Surface– An idealised surface with no resistance to motion.
• Froth Flotation– A method of separating hydrophobic particles from hydrophilic ones.
• Fuel Cell– A device that converts chemical energy directly into electrical energy.
• Full Wave Rectifier– A circuit that converts both halves of AC to DC.
• Fundamental Frequency– The lowest natural frequency of a vibrating system.
• Fusion (Nuclear)– The process where light nuclei combine to form a heavier nucleus with energy release.
• Fusion Energy– The energy released during nuclear fusion reactions.
• Far Point– The maximum distance at which the eye can see without accommodation.
• Field Emission– The release of electrons from a surface due to strong electric fields.
• Filtration (Physics)– Separation of particles from fluids using porous materials.
• Fine Structure Constant– A fundamental constant characterising electromagnetic interaction strength.
• Flash Point– The lowest temperature at which a substance emits vapours that can ignite.
• Fluid Pressure– The force exerted by a fluid per unit area.
• Friction Coefficient– A factor indicating the amount of friction between two surfaces.
• Flux Linkage– The total magnetic flux passing through a coil.
• Fresnel Diffraction– Diffraction that occurs when light is near the source or obstacle.
• Fresnel Lens– A compact lens made of concentric sections to focus light efficiently.
• Frictional Force– The resistive force acting opposite to relative motion.
• Fission Reactor– A device that controls nuclear fission to produce energy.
• Flashover– A sudden electrical discharge across an insulator or gap.
• Flexible Body Mechanics– Study of objects that deform significantly under force.
• Frame of Reference– A coordinate system used to describe motion.
• Friction Welding– Joining materials by heat generated through frictional contact.
• Frictional Losses– Energy lost due to resistance in mechanical systems.
• Foucault Pendulum– A device demonstrating Earth’s rotation via plane oscillation.
• Forward Bias– A condition where a diode conducts current due to proper voltage direction.
• Free Expansion– Expansion of a gas without external pressure or work.
• Frequency Modulation (FM)– Encoding information by varying the frequency of a carrier wave.
• Frictional Drag– Resistance experienced by a body moving through a fluid.
• Fermi Temperature– The temperature equivalent of Fermi energy.
• Frictional Contact– Surface interaction where resistance to movement occurs.
• Feedback Mechanism– A process in which part of a system’s output is returned as input.

Physics Terminology (G)

• Galactic Centre– The rotational centre of a galaxy, often containing a supermassive black hole.
• Galilean Moons– The four largest moons of Jupiter discovered by Galileo: Io, Europa, Ganymede, and Callisto.
• Galilean Relativity– The principle that the laws of mechanics are the same in all inertial frames.
• Galvanic Cell– A device that converts chemical energy into electrical energy through redox reactions.
• Galvanometer– An instrument used to detect and measure small electric currents.
• Gamma Radiation– High-energy electromagnetic waves emitted from atomic nuclei.
• Gas Laws– Physical laws that describe the relationships between pressure, volume, and temperature of gases.
• Gas Pressure– The force exerted by gas particles per unit area on container walls.
• Gauge Boson– A particle that mediates fundamental forces, such as photons or gluons.
• Gauge Pressure– Pressure measured relative to atmospheric pressure.
• Geiger Counter– A device used to detect and measure ionising radiation.
• General Relativity– Einstein’s theory describing gravity as the curvature of space-time caused by mass.
• Geocentric Model– An ancient model placing Earth at the centre of the universe.
• Geodesic– The shortest path between two points in curved space-time.
• Geoid– The shape of Earth based on gravitational variations, approximating mean sea level.
• Geometric Optics– The study of light behaviour in terms of rays and reflection/refraction.
• Geothermal Energy– Heat energy derived from the Earth’s interior.
• Gigahertz (GHz)– A frequency unit equal to one billion cycles per second.
• Gluon– The elementary particle responsible for the strong nuclear force between quarks.
• Graded Index Fibre– An optical fibre with varying refractive index to reduce signal distortion.
• Grain Boundary– The interface where crystals of different orientations meet in solids.
• Grammage– The mass per unit area of a material, common in material science.
• Gravitation– The attractive force between masses.
• Gravitational Collapse– The inward fall of matter due to its own gravity, forming dense bodies like stars or black holes.
• Gravitational Constant (G)– A universal constant used in Newton’s law of gravitation.
• Gravitational Field– A region in which a mass experiences gravitational force.
• Gravitational Lensing– The bending of light due to massive objects like galaxies or black holes.
• Gravitational Potential– The potential energy per unit mass at a point in a gravitational field.
• Gravitational Redshift– The decrease in light frequency when escaping a gravitational field.
• Gravity– The force of attraction between objects with mass.
• Greenhouse Effect– The process by which Earth’s atmosphere traps heat from the Sun.
• Ground State– The lowest energy state of an atom or particle.
• Group Velocity– The speed at which the overall shape of a wave pulse moves.
• Gyroscope– A device that maintains orientation based on angular momentum.
• Gauss’s Law– A law relating electric flux through a surface to the charge enclosed.
• Gaussmeter– An instrument used to measure magnetic field strength.
• Gaussian Distribution– A normal distribution curve common in statistical physics.
• Geiger-Müller Tube– The sensing component in a Geiger counter.
• Geometric Progression (Physics Use)– A sequence modelling exponential change in decay or growth.
• Geyser Principle– The physics of superheated water eruption due to pressure changes.
• Gibbs Free Energy– The energy available to do work at constant pressure and temperature.
• Gigatonne Energy– The energy equivalent to a billion tonnes of TNT, used in astrophysical events.
• Gimbal Lock– The loss of one rotational degree of freedom in a mechanical system.
• Gluon Field– A field generated by gluons that bind quarks together.
• Gold Leaf Electroscope– A device for detecting electric charge through leaf separation.
• Gradient– The rate of change of a physical quantity in space.
• Grating– An optical component with multiple slits used for diffraction.
• Gravimetric Analysis– Determining quantity by measuring weight changes.
• Grey Body– An object that absorbs and emits a fixed fraction of radiation at all wavelengths.
• Guided Wave– A wave constrained to travel through a specific medium or structure.
• Gunn Diode– A semiconductor device used to generate microwave frequencies.
• Gadolinium– A rare-earth element used in nuclear reactors and medical imaging.
• Gauss (Unit)– A unit of magnetic flux density equal to 10⁻⁴ tesla.
• Gaseous Discharge– The ionisation of gas due to electrical current, creating plasma.
• Glancing Angle– The angle between a wave and a reflecting surface’s plane.
• Globular Cluster– A dense spherical collection of stars in a galaxy.
• Granular Flow– The movement of particles behaving neither as a solid nor a fluid.
• Graphene– A single layer of carbon atoms with exceptional electrical and mechanical properties.
• Gravimeter– An instrument used to measure gravitational acceleration.
• Gray (Unit)– The SI unit of absorbed radiation dose, equal to one joule per kilogram.

Physics Terminology (H)

• Hadron– A subatomic particle made of quarks and held together by the strong nuclear force, such as protons and neutrons.
• Half-Life– The time taken for half of the nuclei in a radioactive substance to decay.
• Halo (Astronomical)– A roughly spherical region surrounding galaxies containing stars, gas, and dark matter.
• Hamiltonian– A mathematical function in physics representing the total energy of a system.
• Harmonic Motion– Repetitive oscillatory movement, such as a pendulum or mass on a spring.
• Heat– Energy transferred from a hotter body to a cooler one because of a temperature difference.
• Heat Capacity– The amount of heat needed to change the temperature of a substance by one degree.
• Heat Conduction– Transfer of thermal energy through a material without the movement of the material itself.
• Heat Engine– A system that converts thermal energy into mechanical work.
• Heat Radiation– Transfer of heat through electromagnetic waves, mainly infrared.
• Heat Sink– A material or device that absorbs or dissipates unwanted heat.
• Height– The vertical distance of an object from a reference point, often related to gravitational potential energy.
• Heliocentric Model– The astronomical model in which the Sun is at the centre of the Solar System.
• Helium– A light, inert gas often formed in nuclear fusion or radioactive decay processes.
• Hertz (Hz)– The unit of frequency equal to one cycle per second.
• Higgs Boson– A fundamental particle associated with the Higgs field, giving other particles mass.
• Holography– A technique for recording and reconstructing three-dimensional images using interference patterns.
• Hooke’s Law– The principle stating that the force needed to extend a spring is proportional to its extension.
• Horizontal Motion– Movement parallel to the ground, analysed separately in projectile motion.
• Hydraulic Machine– A device that uses liquid pressure to transmit or amplify force.
• Hydrodynamics– The study of fluids in motion.
• Hydroelectric Power– Electricity generated using the energy of flowing or falling water.
• Hydrogen– The lightest element and a major component in nuclear fusion reactions.
• Hydrostatic Pressure– The pressure exerted by a fluid at rest due to gravity.
• Hyperbola– A type of curve formed when analysing certain motion and orbits.
• Hypercharge– A quantum number used in particle physics to classify subatomic particles.
• Hypersonic Speed– Speeds greater than five times the speed of sound.
• Hypothesis– A testable scientific assumption used as a starting point for experiments.
• Hysteresis– The lag between input and response in systems like magnets or elastic materials.
• Hydrometer– An instrument used to measure the density or relative density of liquids.
• Hydrostatic Equilibrium– The balance between gravity and pressure in stars or planets.
• Hall Effect– Production of voltage at right angles to current and magnetic field in a conductor.
• Heavy Water– Water containing deuterium used as a moderator in nuclear reactors.
• Heisenberg Uncertainty Principle– The concept that certain pairs of physical properties cannot both be known exactly at once.
• Helmholtz Coil– A device of two identical coils used to produce a uniform magnetic field.
• Horizon (Cosmic)– The limit beyond which light has not yet reached an observer in the universe.
• Humid Air– Air with water vapour, affecting density and sound propagation.
• Hydraulic Press– A machine using fluid pressure to apply large forces.
• Hydraulic Lift– A device that raises heavy loads using Pascal’s law.
• Hydrogen Bomb– A thermonuclear weapon powered by hydrogen fusion.
• Hysteretic Loss– Energy loss in magnetic materials due to repeated magnetisation cycles.
• Heat Transfer– The movement of thermal energy via conduction, convection, or radiation.
• Heat Pump– A device that transfers heat from a colder area to a warmer one using work.
• Heat Reservoir– A system that can absorb or release large amounts of heat without significant temperature change.
• Heliocentric Distance– The distance from an object to the Sun.
• Heterodyne– Mixing two frequencies to produce new frequencies.
• Hubble Constant– The rate of expansion of the universe.
• Hubble’s Law– The observation that galaxies move away from Earth at speeds proportional to their distance.
• Hydrophone– A microphone for detecting sound waves underwater.
• Hysteresis Loop– A graph showing the magnetic behaviour of a material through magnetisation cycles.

Physics Terminology (I)

• Ice Point– The temperature at which pure water freezes, defined as 0°C on the Celsius scale.
• Illumination– The amount of visible light falling on a surface, measured in lux.
• Image– A reproduction of an object formed by reflection or refraction of light.
• Impulse– The product of force and the time over which it acts, causing a change in momentum.
• Incident Ray– A ray of light that strikes a surface before being reflected or refracted.
• Inclined Plane– A sloping surface used to raise or lower loads with reduced effort.
• Incompressible Fluid– A fluid whose density does not change significantly under pressure.
• Induced Current– An electric current generated by a changing magnetic field.
• Inductor– A component in an electric circuit that stores energy in a magnetic field.
• Inelastic Collision– A collision where kinetic energy is not conserved, often turning into heat or deformation.
• Inertia– The tendency of an object to resist changes in its state of motion.
• Inertial Frame of Reference– A frame in which an object remains at rest or in uniform motion unless acted on by a force.
• Infrared Radiation– Electromagnetic waves with wavelengths longer than visible light, mainly associated with heat.
• Initial Velocity– The velocity of an object at the start of its motion.
• Injection Laser– A semiconductor laser that emits light through stimulated emission using electric current.
• Innate Heat– Historical term referring to natural warmth within a body, now replaced by internal energy concepts.
• Inner Core (Earth)– The solid, dense central layer of Earth composed mainly of iron and nickel.
• Input Energy– The total energy supplied to a system to perform work or generate output.
• Instantaneous Speed– The speed of an object at a particular moment in time.
• Insulator– A material that resists the flow of electric current or heat.
• Intensity (Wave)– The power transmitted per unit area, often used in sound and light.
• Interference– The superposition of two or more waves resulting in a combined effect.
• Internal Energy– The total energy contained within a system due to molecular motion and interactions.
• International System of Units (SI)– The standard system of measurement used in science.
• Interstellar Medium– The gas and dust present between stars in a galaxy.
• Ion– An atom or molecule with a net electric charge due to gained or lost electrons.
• Ionisation– The process of removing or adding electrons to create ions.
• Ionising Radiation– High-energy radiation capable of removing electrons from atoms or molecules.
• Ionosphere– The ionised layer of Earth’s upper atmosphere affecting radio communication.
• Irregular Motion– Motion that does not follow a predictable pattern or path.
• Isobar– A line on a graph or map connecting points of equal pressure, or isotopes with same mass number and different atomic numbers.
• Isochoric Process– A thermodynamic process occurring at constant volume.
• Isolated System– A system that exchanges neither matter nor energy with its surroundings.
• Isomer– Substances with the same molecular formula but different structural arrangements, relevant in nuclear physics.
• Isothermal Process– A process that takes place at constant temperature.
• Isotope– Variants of the same element with different numbers of neutrons.
• Isotropy– A property of being identical in all directions, common in cosmology and materials.
• Impulse-Momentum Theorem– The principle that impulse equals the change in momentum.
• Image Distance– The distance between an image and a mirror or lens.
• Incident Angle– The angle between an incident ray and the normal to a surface.
• Ion Thruster– A propulsion system that uses ionised gas to produce thrust.
• Inversion (Laser Physics)– The condition where more particles are in an excited state than a lower state, allowing laser action.
• Inverted Image– An image that is upside down compared to the object, often produced by lenses.
• Ising Model– A mathematical model for understanding magnetism in materials.
• Isentropic Process– A process that is both adiabatic and reversible, with constant entropy.
• Isometric Projection– A form of visual representation used in physics diagrams to show 3D objects.
• Ion Exchange– A process used to remove ions from solutions, often in water purification and physics experiments.
• Ideal Gas– A gas that follows the ideal gas law with no intermolecular forces or volume of particles.
• Ideal Gas Law– The equation  PV = nRTPV = nRT,  relating pressure, volume, temperature, and amount of gas.
• Impedance– The total opposition a circuit offers to alternating current, combining resistance and reactance.

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-1 (A to E)

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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