a value characteristic of a particular medium that represents the amount of light or sound it absorbs from a wave passing through it.

the rate at which the velocity of an object increases over time.

the extent to which measurements of a property differ from its actual value.

the study of sound; also, the qualities of a space that affect how sound is heard within that space.

the minimum energy required for a chemical reaction to take place.

the region in the center of certain types of galaxies that emits massive amounts of energy across most, if not all, of the electromagnetic spectrum; believed to result from a supermassive black hole.

the ratio comparing the output force of a machine to the input force, taking into account friction and other factors that limit the efficiency of real-world machines. A mechanical advantage of more than one indicates an amplification of force.

the portion of electromagnetic energy that is reflected when its waves encounter a surface or boundary; often used to describe solar radiation reflecting off Earth or another body in space.

a form of radioactive decay in which a radioactive atom’s nucleus splits and discharges an alpha particle, made up of two protons and two neutrons.

a particle consisting of two protons and two neutrons, identical to a helium nucleus, which is emitted from an unstable nucleus via radioactive decay.

alpha (α) particles typically emitted during alpha decay, a subtype of radioactive decay.

the rule stating that the strength of a magnetic field about a current-carrying conductor is directly proportional to the magnitude of the current.

an imperfect reproduction of the original signal when transmitting sound electronically.

a quantifying wave property measured from a point of rest to a point of maximum displacement; related to sound power and intensity of sound waves.

the separation along a curved path between two rays originating at the same point.

the angle subtended at the eye by a magnified image of an object divided by the angle of the object being viewed by the naked eye without magnification.

the rotational momentum of an object around an axis, defined as the product of its moment of inertia and its angular velocity.

the speed and direction of movement of a rotating object.

a subatomic particle with a neutral charge, the antiparticle to the neutrino, which is emitted during beta decay.

a point of maximum amplitude in a standing wave.

waves with a phase difference of 180 degrees relative to one another. The crests of one wave align with the troughs of the other and vice versa.

an adjustable opening in a barrier through which light or other electromagnetic emission can pass.

the length of an arc defined by an angle and two radii.

the loss of energy from a wave passing through a medium due to absorption or scattering.

in physics, the overall value for a given quantity, obtained by comparing initial and final values of a measurement against another unit or quantity; for instance, average speed compares the total distance traveled to the total time taken to move that distance.

the center around which an object rotates.

the total amount of ionizing radiation to which Earth is constantly exposed from both natural and artificial sources.

the motion described by a projectile traveling by inertia in a gravitational field.

the optical distortion caused by a wide-angle lens that makes an image seem inflated at the center, as though stretched across a barrel.

the energy output of burning one barrel (42 gallons, or 159 liters) of crude oil; equal to 5.8 × 106 BTU or 6.1 × 109 joules.

the apparent frequency at which waves from two or more sources create constructive interference.

a formula that relates the attenuation of an electromagnetic wave in a given medium to the thickness of that medium and the concentration of attenuating materials within it.

used to relate and determine velocity, acceleration, and density in fluid mechanics.

an electron that is emitted from an unstable nucleus via radioactive decay.

beta (β) rays emitted during beta decay, a subtype of radioactive decay.

the extent to which a measurement differs from the real value of the property being measured, or an intrinsic factor in a method that consistently causes such deviation.

radiation emitted by a body solely as a result of its temperature, regardless of its composition or any previously absorbed radiation.

the apparent shortening of the wavelength of electromagnetic radiation due to the movement of the radiation source toward the observer.

the ratio of the probability of finding a particle or system at a certain energy level to the probability of finding it at another energy level; proportional to the probability of the system being in a particular quantum state.

the energy required to break the chemical bonds in one mole of molecules and separate them into their component atoms.

an elementary particle that carries a specific type of force, or a composite particle containing an even number of fermions, having an integer spin.

in string theory, the structure of bosons as one-dimensional strings rather than dimensionless points.

a system of mathematical notation developed by physicist Paul Dirac to manipulate very large vector equations more easily.

radiation generated when a particle is slowed via a collision with another particle; from the German word for “braking radiation.”

a nonstandard unit of energy measurement supposedly equivalent to the heat needed to raise the temperature of one pound of water by one degree Fahrenheit.

upward force exerted by a fluid on a submerged or floating object.

the amount of energy needed to raise the temperature of one gram of water by one degree Celsius (1.8 degrees Fahrenheit) at one atmosphere of pressure, equivalent to approximately 4.2 joules.

an electrical part consisting of two conductors separated from each other by a nonconductor, allowing it to store electrical charge temporarily.

capable of causing cancer.

a system that uses a pair or trio of numbers to indicate the location of a point in two-dimensional or three-dimensional space relative to a set point of origin.

a pair or triplet of numbers that indicate the location of a point in a plane or in a three-dimensional space and are the signed distances from the origin.

the point in an object or system around which the mass of said object or system is evenly distributed.

the inertial frame of a system where the vector sum of the moments of all of the particles in that system is zero.

a fictitious force that seems to push a body in circular motion away from the axis of rotation; an artifact of a non-inertial frame of reference, in any inertial reference frame, objects in circular motion are subject to centripetal force.

a force “toward the center” that, in combination with inertia, generates the curved path of an object in circular motion.

electromagnetic radiation emitted when a charged particle, such as an electron, travels through a given medium faster than light would in that same medium.

a distortion created by the separation of white light into its component wavelengths when passing from one medium into another, such as through a lens.

an imperfect image produced by a lens due to the rays of light passing through it not converging at a perfect point.

a closed path along which electricity travels.

the distance around a circle defined by a radius.

a system that may exchange energy, but not matter, with its surroundings.

parallel rays of light that propagate with minimal spreading.

an interaction in which two or more bodies come into contact and briefly exert force on each other.

a property of quarks that distinguishes quarks and gluons from each other.

the force of the strong interaction that operates on the quark level.

the extended geometric image formed along the optical axis of a lens by light entering the lens obliquely.

the pushing forces applied to an object in order to diminish its size or volume.

the ability of a material to resist deformation or structural failure when experiencing a force of compression (squeezing).

the collision of a high-energy photon with a lower-energy electron, causing energy to be transferred from the photon to the electron and changing the angle of the photon’s trajectory.

having surfaces that curve inward, like a bowl.

a material that has a low resistance to electric charges, allowing them to move through it easily.

a quantum field theory that is independent of the scale of the system and supports only massless excitations.

a fundamental law of physics that states that the amount of energy in a system remains constant over time. Although the energy can be transformed or transferred, it cannot be created or destroyed.

in physics, the principle that the total momentum in a closed system is always constant.

when two or more waves of the same phase combine to form a larger amplitude.

the amount of energy used or transferred over a period of time, often measured in kilowatt-hours.

a clear path for electricity from point A to point B.

the idea that there are limitless levels of energy between each point on a continuum.

the joining of light rays after an interaction with a mirror or a lens.

having surfaces that curve outward, like a ball.

a trigonometric function describing the relationship between sides of a right triangle; the cosine of an angle is equal to the length of the side adjacent to the angle divided by the length of the hypotenuse.

extremely high-energy subatomic particles, mainly protons and atomic nuclei, that originate outside of Earth’s atmosphere from largely unknown sources.

the basic unit of charge in the International System of Units (SI).

a scientific law stating that the electric flux at any defined surface is the vector sum of the electric field strength at every point on that surface.

the highest point of a wave from its neutral value; the distance between the crest or trough of a wave and the wave’s neutral value is called the amplitude.

an operation, broadly analogous to multiplication, performed on two vectors in a three-dimensional space that results in a third vector that is perpendicular to both; if both vectors have the same direction or if one of them has a value of zero, the cross product will be zero.

the rate at which an electric charge, usually in the form of electrons, moves through a wire or other conductive material.

an oscillator that is subject to friction or other braking forces.

the rate at which the velocity of an object decreases over time.

a logarithmic unit that describes the power of a given sound in relation to the threshold of human hearing; abbreviated dB.

a sound in which the pitch is easily detected.

the number of physical parameters required to specify the position and configuration of a particle or other body.

the load on an electrical supply system over time.

a measure of the mass of a quantity of matter relative to the volume of space that it occupies.

the range of distance over which objects appear sharp or in focus.

unit of measure that is described in terms of two or more base units; for example, meters are a base unit of distance, whereas square meters are derived units of area calculated from meters of height multiplied by meters of depth.

when two or more waves of different phases combine to form a smaller amplitude.

a circular structure with an aperture that controls the amount of light entering an instrument.

a change in the direction of a wave as it passes around an obstruction or through an opening.

a direction in which an object can move. In spatial physics, the three dimensions are traditionally represented by the symbols x, y, and z.

devices in which an anode and a cathode, or the transistor equivalent, control the direction of current flow.

a relationship between two parameters that exists if increasing one increases the other according to a set multiplier.

the difference between the measured value of a property and its real value, or between nonidentical measurements of the same property.

in fluid mechanics, the process by which a body immersed in a fluid pushes the fluid out of the way and occupies the space in its stead. The volume of the displaced fluid is equal to the volume of the displacing body. The absolute distance and direction between the starting and end points of an object’s motion, which ignores any twists or turn the object’s path may take; it is always equal to or less than the total distance traveled.

in electrodynamics, the electric field produced solely by free charges (e.g., free electrons).

the irreversible loss of energy from a system.

the ability of particles with the same energy to be differentiated from one another.

a mathematical function that describes the probability that a certain variable, such as the energy state of a particle, will have a given value or range of values.

the separation of light rays after an interaction with a mirror or a lens.

the product of the lengths of two vectors and the cosine of the angle between them; also called the inner product or the scalar product.

a device applied to an electrical circuit or other system in order to provide a corresponding load without performing an output function.

the state in which reversible reactions occur at equal rates in opposite directions, balancing each other and resulting in no net change.

systems that are subject to change.

a device that measures mechanical power or force, often used for the output of engines and other similar devices.

a unit of force in the centimeter-gram-second (CGS) unit system, equal to 10−5 newtons, or 10 micronewtons.

the measure of how effective a machine is at transforming or transferring energy, quantified as the ratio of the actual performance of the machine to an idealized, theoretical version of it. A perfect machine would have an efficiency value of one.

the measure of how effective a machine is at transforming or transferring energy, quantified as the ratio of the actual performance of the machine to an idealized, theoretical version of the same machine. A perfect machine would have an efficiency value of one.

any mathematical function for which the operation being considered yields the original function multiplied by a constant (an eigenvalue). Eigenfuctions are defined only with respect to the operator for which the eigenfunction is considered

the state for which the value of a measurable, observable operator is defined without uncertainty

the set of all eigenvectors of a matrix paired with their respective eigenvalues.

the mathematical constant that, when multiplied by an eigenfunction, yields the result of that operation performed on the function.

the measure of the strength of an electric field across an area with different electrical potentials.

energy that is present in particles due to their charge and closeness to other charges.

the ratio of the power applied to an electrical circuit to the power delivered by a particular device in the circuit.

a device that becomes magnetic due to the presence of an electric current.

a physical field consisting of a combined electric field (generated by stationary electric charges) and magnetic field (generated by moving electric charges) that affects the behavior of charged objects in its vicinity.

the full range of electromagnetic radiation, sorted into segments with similar properties by wavelength; x-rays occupy one of these segments.

the energy per unit of charge supplied by an electric source such as a battery, measured in volts.

a negatively charged subatomic particle that is often bound to the positive charge of the nucleus but can also exist in a free state in an atom.

the amount of energy carried by a single electron moved across an electric potential difference of one volt; equal to 1.6 x 10⁻¹⁹ joules.

the force responsible for nuclear transformations.

one of the fundamental constituents of matter.

the parts of an electrical circuit, each of which has a specific function.

an oval surrounding two focal point points where the sum of the distances from any point on the oval to the two focal points is constant.

the lengthening of an object under stress.

describes a chemical reaction or process that requires the input of energy from an external source in order to proceed.

a property of matter and objects that can be transferred and transformed but never created or destroyed, sometimes described as the ability to do work; measured in joules (J).

a measure of the total internal energy (thermal energy) of a system, the product of its volume and pressure.

a measure of a system’s level of disorder, which in physics refers to the potential amount of states the molecules of the system may assume.

the condition of a thermodynamic system in which there is no energy flow.

describes a chemical reaction or process that results in an output of energy from the system.

any characteristic property of matter that is due to the interaction of the matter with an external factor.

the scientific law stating that when a magnetic field and a conductor move relative to each other, a voltage is induced in the conductor, the magnitude of which depends directly on the relative speed of the field and conductor.

one of two main classes of particles, characterized by adherence to Fermi-Dirac statistics; includes quarks, leptons, and any particles that contain an odd number of quarks or leptons, such as protons and neutrons.

describing material that can be made permanently magnetic by the presence of a magnetic field, such as iron and other ferrous (iron-like) metals.

a frame of reference that is fixed to the environment and not to the subject being observed; sometimes specified as “Earth-fixed” or “space-fixed.”

the amount of fluid that flows in a given period of time; expressed as a numerical quantity.

the distance from the focal point of a lens or mirror to the center of the lens or mirror.

the place where light from a source converges after it reflects off a mirror or refracts through a lens.

a push, pull, or any other interaction that affects the motion of an object. Force is measured in newtons (N).

the effect of a field force and a function of the relative position of the object from the force field source; the object and the source do not need to be in physical contact for this effect to occur.

a set of coordinate axes that serve to describe position or movement of an object with reference to that coordinate system.

falling only under the influence of gravity.

the number of complete wavelengths that occur within one unit of time, typically expressed as hertz (Hz; cycles per second).

the force created by the resistance to relative motion between solid surfaces.

the force created by the resistance to relative motion between solid surfaces; it is normally proportional to the roughness of the surfaces as well as the force squeezing the surfaces together.

the supporting point around which a lever pivots.

the lowest frequency of a resonating medium; also called the first harmonic.

electromagnetic radiation with a wavelength shorter than 1 × 10⁻¹¹ meters; gamma (γ) rays typically emitted during gamma decay, a subtype of radioactive decay.

a high-energy photon that is usually emitted by an unstable nucleus via radioactive decay; it may also be produced by various other means, including particle-antiparticle annihilation and the interaction of atmospheric particles with cosmic rays.

a high-energy flash of gamma radiation produced by a violent explosion in a distant galaxy; believed to be the brightest and most energetic electromagnetic event in the universe since the big bang.

any closed or finite hypothetical surface.

a device that can be used to detect alpha radiation as well as beta radiation, gamma radiation, and x-rays.

the theory stating that gravity is a geometric property of space and time.

the elementary particle that carries the strong interaction between quarks. Abbreviated g, a standard unit of mass in the International System of Units; derived from the kilogram (kg, thousands of grams), which is the base unit of mass.

the rate of increase of velocity experienced by matter under the influence of a gravitational field; often referred to as the force of gravity.

the pull that objects exert on each other due to their masses and the separation between their centers of mass.

the gauge boson that mediates the gravitational force.

the force that describes the attraction between one body and another.

a direct connection to a larger body by which excess current is carried away, preventing errant electrical potentials from being generated in the circuit.

a subatomic particle that is made of either three quarks or one quark and one antiquark and held together by the strong force.

the average time it takes for half of the unstable nuclei in a radioactive element to undergo radioactive decay, transforming into a lighter element and giving off radiation.

the motion resulting from a system that when displaced from its equilibrium point exerts a restoring force that is proportional to the displacement.

the study of the interaction of wave phenomena.

the combination of two or more different musical notes played simultaneously that create a pleasant sound.

the active process of energy transfer due to changes in an object’s thermal energy.

transfer of thermal energy from one region or system to another.

a measurement of the energy released as heat when a specific amount of a specific substance is burned; typically applied to fuels and foods in units of energy or mass.

the SI unit of frequency; one hertz (Hz) is equal to one cycle (complete orbit) per second.

the principle that the overall enthalpy change of a given reaction remains the same regardless of the number of reaction steps involved and is equal to the sum of the enthalpy changes of any and all intermediate steps; also called Hess’s law of constant heat summation.

a theorized field that, through interactions with matter, causes that matter to have mass.

the law stating that the deformation of an elastic object, such as a spring, is directly proportional to the force acting on the object, as long as the object’s elastic limit is not exceeded.

an alternative unit of power, in theory based on the amount of power an average horse can produce; commonly used to describe engines.

a nonstandard unit of power supposedly equivalent to the amount of work a horse does over an hour.

in an electrical circuit, the conductor that brings current into a component element (the conductor having the higher electrical potential).

a law stating that the pressure (P) and volume (V) of an ideal gas are directly related to its number of particles (n), its temperature (T), and the ideal gas constant (R), written as PV = nRT.

the ratio comparing the output force of a machine to the input force, ignoring friction and other factors that limit the efficiency of real-world machines. A mechanical advantage of more than one indicates an amplification of force.

the opposition to electrical current flow produced by a voltage.

any system that functions with less than 100 percent efficiency.

a turbine set in motion by the velocity of a fluid hitting each blade.

unable to be pressed or squeezed.

a sound in which the pitch is not easily detected.

the property by which a current is created in conductors to resist a change in the magnetic field through the conductor.

a conducting coil in which the current generates a proportional magnetic field that, in turn, impedes the flow.

the principle that an object at rest tends to stay at rest and an object in motion tends to stay in motion unless acted on by an outside force.

a means of describing relative motions through space according to Newtonian mechanics.

a sound wave with a frequency below twenty hertz, the lower limit of human hearing.

the velocity of an object at the start of some interval of time.

the force (or energy) that is “put in” to a machine; for example, the horizontal force of wind provides the input for a windmill.

denotes a measurement taken at a specific point in time.

the time-variant angle of a sinusoidal function.

the velocity (speed and direction of travel) of an object in motion at any one instant of time.

a material that has a high resistance to electric charges, preventing them from moving through it easily.

substances that cannot transport electricity.

in acoustics, sound power per unit area; measured in decibels or watts per square meter.

the distortion of a wanted signal by an unwanted one, such as an unwanted radio station “bleeding into” another because both are broadcasting on the same wavelength.

for an ideal gas, the energy of its atoms and molecules that is directly proportional to the absolute temperature.

a standardized system of units and measures based on the metric system, used worldwide to enable clear and precise communication in the sciences and other disciplines.

any characteristic property of matter that is due solely to the nature of the matter itself.

a collision between a high-energy electron and a low-energy photon that results in energy being transferred to the photon.

a relationship between two parameters that exists if increasing one decreases the other according to a set multiplier.

radiation emanating from a single point has an intensity inversely proportional to the square of the distance the radiation has traveled from its source.

the reversal of the way an image looks after an interaction with a mirror or lens.

variants of a chemical element with differing numbers of neutrons

abbreviated J, the International System of Units unit of work and energy. One joule is equal to the work done by a force of one newton acting across a distance of one meter.

the amount a parameter, such as sound intensity, must be changed so that the difference is noticeable at least half the time.

a nonstandard unit commonly used to measure energy content in food.

the base unit of mass in the International System of Units (SI), equal to 1,000 grams (2.2 pounds).

a unit measuring work over time, equivalent to 1,000 watts, or joules per second

a unit for measuring electricity consumption, equal to one thousand watts of power consumed over one hour, or 3.6 × 106 joules.

a subfield of classical mechanics that studies the motion of objects without reference to the forces that cause this motion.

energy due to any kind of motion, be it rotation, vibration, or translation.

the theory that atomic and molecular motion determines the behavior of gases.

positions where the gravitational pull of two large masses equals the centripetal force needed for a small object to maintain a stable position in orbit with the two large masses.

the even and stable flow of a fluid; opposite of turbulent flow.

the total amount of energy in a closed system is always the same; therefore, energy can neither be created nor destroyed.

the law that states if the fulcrum of the lever is closer to the output end than the input end, it will generate a mechanical advantage.

the principle that the current induced in a conductor by a moving magnetic field flows in the direction opposite to the motion of the magnetic field.

an elementary particle that has no color and thus cannot form nuclei.

the force that directly opposes the weight of an object and the force of gravity and holds the object aloft.

an oscillation in an electromagnetic field.

the lines of color that represent the characteristic frequencies at which atoms emit electromagnetic radiation.

the ratio of the apparent height of an object’s magnified image to the actual height of the object.

an object’s mass times its velocity; often called simply “momentum,” as the basic concept is defined in terms of an object moving in a straight line.

the power to which a fixed numerical base (the default is 10) must be raised to produce a given number.

a type of wave wherein the medium is displaced in a direction parallel to the movement of energy, as in the case of sound waves.

a means of describing relative motions through space according to the mathematics of relativity.

the intensity of sound waves, which depends on the wave’s amplitude; measurements of loudness or volume are expressed in decibels.

the measure of the strength of the magnetic field surrounding an active electrical conductor or a magnet, equal to the product of the external magnetic field (B), the area of the affected surface (A), and the cosine of the angle between them (cosθ).

the generation of magnetism within a magnetizable material by proximity to a magnetic field.

the size, or numerical measurement, of a vector.

how much matter there is in an object; measured in kilograms Mass determines the effects of gravitation and inertia. Unlike weight, which is dependent on gravitation, an object’s mass remains constant throughout the universe.

a system consisting of an elastic object connected to an object with mass.

a mathematical notation in which a series of coordinates is written in an array and can then be manipulated according to set rules.

anything that can be characterized as having mass and can be measured by some criterion of measurement.

the point of greatest wave height, also known as a crest or peak. It is the point of greatest positive displacement from the position of rest in a wave.

the mathematical relationships governing electromagnetism, as formulated by James Clerk Maxwell.

quantifying an observation (e.g., the length of a person’s foot) using discrete units (e.g. meters); alternately, the unit or system used to do so.

the amplification of force provided by many machines, measured as the ratio of the output force to the input force.

the ratio of the power applied to a mechanical system relative to the power delivered by the system.

the increase in the amplitude of motion by a medium in response to a periodic applied force or a sympathetic vibration close to the fundamental frequency.

devices that use moving parts and direct physical force to bring contacts together to let electricity flow.

the SI base unit of distance (or length) measurement.

the point of greatest wave depth, also known as a trough or valley. It is the point of greatest negative displacement from the position of rest in a wave.

being able to transform a dynamic system with multiple phase spaces in its initial state in more than one way over time to reach a target state that has com­pletely overlapping phase spaces.

a quantity of a pure substance made up of exactly 6.02214129 × 10²³ atoms or molecules, the mass of which in grams has the same value as the mass of one atom or molecule of the substance in unified atomic mass units.

a combination of a physical quantity and a distance with respect to a fixed axis; the physical quantities of an object as measured at some distance from that axis.

an intrinsic property of matter, the product of mass and velocity.

a physical model of the structure of the universe that encompasses all consistent versions of superstring theory.

in biology, a change in the structure of a gene. Ionizing radiation such as beta radiation can alter the electric charge of the atoms in a gene.

the sum of all of the forces acting on an object; note that forces with equal magnitude but opposite directions negate each other. An object moves in the direction of the net force acting on it.

in an electrical circuit, the conductor that accepts the current coming out of the component elements (the conductor having the lower electrical potential).

subatomic particles that, with protons, make up the mass of an atom’s nucleus; they have functionally the same weight as protons but no electric charge.

abbreviated N, the International System of Units unit of force. One newton is equal to the force required to accelerate a one-kilogram mass at one meter per second per second.

a device used to measure force; also called a “force meter” or a “force gauge.”

three laws devised by physicist and mathematician Isaac Newton to describe the motion of objects in relation to the forces acting on them.

three laws, defined by Isaac Newton, that describe the motion and forces acting on large objects moving at speeds much smaller than the speed of light.

the International System of Units standard unit for torque; one newton-meter (N·m) is equal to the torque resulting at the axis from the force of 1 newton applied perpendicularly to an attached 1-meter-long moment arm (i.e., a lever).

a point of minimum amplitude (typically zero) in a standing wave.

in acoustics, any sound whether wanted or not; may also describe background sound that obscures a desired signal or sound.

radiation that lacks the energy necessary to knock electrons free when it hits an atom; all electromagnetic radiation with a longer wavelength than ultraviolet is nonionizing.

electromagnetic radiation that lacks the energy necessary to knock electrons free when it hits an atom; all types of electromagnetic radiation with a longer wavelength (less energy) than ultraviolet is non-ionizing.

devices that use electromagnetism to open and close a circuit.

a fluid that flows without friction.

the force exerted on an object perpendicular to the surface of contact.

a type of baryon, either a proton or a neutron, that is found in atom’s nucleus.

a progression of eight harmonic tones.

an empirical law stating that the current, or flow of electrical charge, between two points is directly proportional to the voltage, or difference in electric potential, between those points.

a system in which both matter and energy can be exchanged between the system and its surroundings.

a system of mirrors, lenses, or prisms that can be used for imaging in an instrument such as a telescope or microscope.

the science of the interaction of light with lenses and mirrors.

a variation between maximum and minimum values of displacement from a neutral value.

the force (or energy) produced by a machine. The machine transforms the input into the output; for instance, a windmill transforms the force of wind (input) into the circular motion of a millstone for grinding (output).

a frequency that is a whole-number multiple of the fundamental frequency of a resonating medium.

refers to a shape (a parabola) that can be described by an equation of the form y = ax² + b.

circuits or segments of circuits in which any two different elements are joined at two common points side by side.

the value of the amplitude at its maximum displacement from the neutral value of the wave.

the absolute value of the sum of the peak positive and peak negative amplitudes; the distance between the crest and the trough of a wave.

a suspended mass that can undergo regular oscillations.

the ability to perceive mechanical waves in one’s environment (e.g., air, water) as sounds, limited by the physiology of the ear and the brain’s ability to interpret information from sound waves.

the length of time for one complete cycle of a wave or other cyclic property to occur.

the extent to which a property repeats over time; regular recurrence.

the ability with which a magnetized material supports a magnetic field.

a measure of the ability of an electric field to penetrate a medium.

set at 90 degrees to a line or surface, forming a right angle.

a disturbance in the motion or orbit of a massive body due to the gravitational pull of or impact with another object.

the application of known solutions to simple quantum mechanical systems (such as that of the hydrogen atom) to more complex systems that cannot be resolved easily.

a stage in a wave property; typically used to describe the relationship of two or more waves.

also called phase difference; the time interval or phase angle that results when one wave is ahead of or behind another.

a space containing all possible states of the particles in a given system, wherein each state is represented by a single point.

a unit of measure for the perceived loudness of sounds; compares all sounds to a baseline sound of 1,000 hertz (1 kilohertz) frequency.

the absorption of the energy of electromagnetic radiation into matter; different substances absorb radiation at different rates.

a phenomenon that describes the emission of electrons from matter (typically metal) upon exposure to electromagnetic radiation.

a massless elementary particle that is the smallest possible unit, or quantum, of light and other electromagnetic radiation.

the ratio of the circumference of a circle to its diameter, symbolically represented as π. Its numerical value is approximately 3.14159.

the optical distortion caused by a telephoto lens that makes an image seem bunched up in the center.

the perceived relative frequency of audible sound waves.

a mathematical description of the amount of radiation emitted at different frequencies by a blackbody at a given temperature.

a pair of numbers indicating a point’s length (radius) from a fixed center, called the pole or origin, and the angle between the radial and the polar axes.

the process by which the motion of electromagnetic waves, which is perpendicular to the direction of energy transfer, is brought into alignment in the same plane.

contact points that complete the circuits in switches.

in quantum mechanics, an electron’s location in space relative to the nu­cleus of an atom.

a subatomic particle that has the same mass as an electron as well as an equal-but-opposite electric charge, that is, a positive charge.

the energy stored within an object due to its position (e.g., gravitational pull on a stationary object above the ground) or its configuration (e.g., an electrical charge or chemical makeup).

a standard unit of mass in the imperial and US customary measurement systems, equivalent to 0.45359237 kilograms; also used as a unit of force.

the rate of work (energy transfer) over time; the International System of Units unit of power is the watt (W), which equals one joule per second (J/s).

the maximum electrical power a device can use without being damaged.

the extent to which different measurements of the same property differ from one another.

the force exerted per unit area.

the math function that describes the probability of an electron being found in a defined region of space about an atomic nucleus.

subatomic particles that, with neutrons, make up the mass of an atom’s nucleus; they have functionally the same weight as neutrons but hold a positive electric charge.

a lone disturbance passing through a medium from one place to another, similar to a wave but not cyclical and repeating.

a distortion common in digital signal processing, such as encoding music as audio files, that results from mapping an original signal of possibly infinite values to a signal with a smaller, countable set of values.

a quantum field theory that describes the interactions of quarks and gluons, subatomic particles that are responsible for the strong interaction.

a theory that explains interactions between subatomic particles as the result of a field extending between them.

the branch of physics that deals with matter interactions on a subatomic scale, based on the concepts that energy is quantized, not continuous, and that elementary particles exhibit wavelike behavior.

the condition of a physical system as defined by its associated quantum attributes.

an elementary fermion that combines with other quarks to form a baryon, such as a proton or a neutron, or with an antiquark to form a particle called a meson.

abbreviated rad, the International System of Units standard unit of angular measure, the length of the corresponding arc in a unit circle. A full circle is composed of 2π radians.

(rad) the SI unit of measure for angles, based on relationship between the radius and circumference of a circle.

energy consisting of electromagnetic radiation; an important mechanism for the transfer of energy in or out of some systems.

energy transmitted via electromagnetic waves (e.g., light, heat, x-rays) or subatomic particles (e.g., alpha particles, beta particles).

electromagnetic radiation with a wavelength between 1 × 10⁻³ and 1 × 10⁵ meters; able to travel long distances without being broken up by atmospheric interference.

the loss of energy and matter from an unstable nucleus in the form of ionizing radiation.

a chemical element with unstable nuclei that give off radiation due to variations in the number of neutrons they contain.

distance from the center of a circle to any point along the circle.

a measurement error that is due to unpredictable and inconsistent factors that do not affect all measurements equally.

the horizontal distance that a projectile can travel before striking the ground.

the ratio of a unit, such as distance or weight, relative to a period of time.

the scattering of electromagnetic radiation when it encounters particles much smaller than the radiation’s wavelength, as, for example, the scattering of visible light in the atmosphere.

a turbine set in motion by the pressure and flow of a fluid.

the inverse of a value, calculated as 1 divided by the value.

the apparent lengthening of the wavelength of electromagnetic radiation due to the movement of the radiation source away from the observer.

the velocity of an object relative to the objects around it and the point of observation.

the rebounding of a wave from a surface or boundary between two mediums, causing it to travel back through the original medium.

the alteration of a wave’s path, speed, and wavelength when it passes from one medium to another.

the effect in which a luminous beam appears brightest when pointing directly at an observer.

a mathematical procedure by which processes occurring on very different scales can be aligned.

a device or material that resists the flow of electrons through it.

the ability of a detector to differentiate or separate different wavelengths.

the response of an elastic body to a force acting on the body at its natural frequency.

describes circular motion wherein an object circles around an external axis (e.g., the moon orbiting Earth); contrast to rotation, wherein the axis is internal (e.g., the moon spinning about its axis).

a technique used to find the direction of magnetic forces and induced currents by using the right hand. The direction of the current is expressed by the fingers, and the direction of the magnetic field is expressed by the extended thumb. If a wire is grasped in the right hand with the thumb pointing in the direction of current flow, the fingers will point in the direction of the magnetic field around the wire.

an idealization of a solid object that assumes that it cannot be deformed by the forces acting on it.

for sinusoidal wave systems, the square root of the sum of squared amplitude values divided by the number of amplitude values.

the kinetic energy of a spinning object.

the number of times an object rotates about a fixed axis in a set amount of time, typically measured in revolutions per minute (rpm).

a quantity that is fully described by a numerical value alone, such as speed, length, or mass.

in music, a group of notes arranged by pitch or frequency. A description of the area under observation in broad approximation.

a wave equation that describes the quantum state of a particle or system and can be used to predict its most likely future behavior.

the ability of an ear or a mechanical device to pick up and interpret sound; highly sensitive devices will have a smaller just-noticeable difference values.

circuits or segments of circuits in which any two different elements are joined only at one common point end to end.

the ratio of total signal power received to noise and distortion received, indicating how well a signal or waveform has been reproduced.

the simplest devices capable of generating a mechanical advantage.

a simple mechanical device that redirects or amplifies force.

a trigonometric function describing the relationship between sides of a right triangle; the sine of an angle is equal to the length of the side opposite the angle divided by the length of hypotenuse.

having a shape or pattern of behavior that can be described by a sine wave function.

a curve that is like a sine wave but experiences a shift in amplitude or phase.

a line on a graph that indicates the rate of change over time; for instance, on a plot of the distance traveled by an object over time, the slope equals the speed of travel and its shape can convey information about acceleration.

a unit of mass in the foot-pound-second (FPS) system, defined as the amount of mass that will experience an acceleration of one foot per second squared (1 ft/s²) when acted upon by one pound-force (lbF); equivalent to approximately 14.5939 kilograms or 32.1740 pounds.

a mathematical description of the refraction of light as it goes from one medium to another.

a method of using sound waves to “see,” typically in an underwater environment, by sending and receiving pulses of sound; originally an acronym for “sound navigation ranging.”

a unit for quantifying perceived loudness; one sone equals forty phons.

the use of ultrasound in medicine to produce images of internal structures, such as tendons, muscles, and organs.

the effects created when an object travels faster than the local speed of sound.

the theory that states that for all inertial nonaccelerating reference frames, the laws of motion remain the same, and that speed of light in a vacuum is the same for all observers, regardless of the observer’s movement relative to the source of light or the movement of the source itself.

the ratio of the density of a substance to that of a standard reference substance; also known as relative density.

the distance traveled per unit of time.

a sound wave’s traveled distance per unit of time.

the blurring or distortion of an image produced by a spherical lens or mirror due to differences in the refraction of light that enters the optical system along the optical axis and light that enters closer to the edge of the lens.

an intrinsic form of angular momentum carried by elementary particles, composite particles (hadrons), and atomic nuclei.

a mathematical value that defines the stiffness of a spring. A characteristic factor of a particular spring that determines the expansion or contraction of the spring when displaced by a specific force.

the change in enthalpy that results from the formation of one mole of a given substance, with the reactants and the products in their standard states.

a generally accepted unified framework of particle physics that explains electromagnetism, the weak interaction, and the strong interaction as products of interactions between different types of elementary particles.

a set of standard thermodynamic reference conditions for a given substance, generally calculated at a temperature of 298.15 kelvins (25 degrees Celsius or 77 degrees Fahrenheit) and a pressure of 105 pascals (14.5 pounds per square inch).

standard reference conditions when dealing with gases, defined by the International Union of Pure and Applied Chemistry as a temperature of 273.15 kelvins (0 degrees Celsius or 32 degrees Fahrenheit) and pressure of 101.3 kilopascals (1 atmosphere); used in chemistry and physics to establish a standardized set of conditions for experimentation.

a wave pattern that maintains a static series of nodes and antinodes within a specific wavelength.

external factors, such as temperature and pressure, that determine the physical state of matter.

electrical energy resulting from an imbalance in electrical charges.

the pressure of a fluid on an object when that object is at rest relative to the fluid.

a mathematical description of the total radiant energy emitted by a blackbody, relating it to the temperature of the blackbody raised to the fourth power.

the force that binds nucleons together in a nucleus.

the fundamental process of particle interaction that binds quarks into hadrons and hadrons into nuclei.

in quantum mechanics, the concept that a particle exists in all possible states at the same time until either its position or its energy is known.

the theory that all bosons have partner fermion particles

the total area of the outward-facing surface of a three-dimensional object.

radiation emitted by the acceleration of a charged particle traveling in a magnetic field at near light speed.

a physical or conceptual delineator between a system and the outside environment.

the proportion of a system’s input it converts to the intended output.

the individual components that work together and make up an overall system used to complete a task.

a force, such as voltage or torque, applied to a system.

the work that the system performs.

a measurement error that is due to intrinsic, mechanical, or environmental factors that affect all measurements equally.

in a right triangle, the ratio of the length of the side opposite an acute angle to the length of the side adjacent to the same angle.

the average kinetic energy of particles that make up a substance.

a measurement of the rate of temperature change over distance.

the ability of a material to resist structural failure when experiencing a force of tension (pulling).

the force directed along the length of a wire, string, or cable pulled at opposite ends.

the velocity at which the acceleration due to gravity of an object falling freely through a fluid medium, such as air or water, is exactly balanced by the deceleration of the object due to resistance from that medium.

the energy released by burning 100 cubic feet (2.83 cubic meters) of natural gas; equal to 1.02 × 10⁵ BTU or 1.08 × 10⁸ joules.

the ease with which heat propagates through a material; measured in watts per meter kelvin.

the ratio of the work performed by a system relative to the heat energy that is supplied to the system.

energy generated by the movement of particles within an object or substance.

electromagnetic radiation generated by charged particles in matter being moved around by heat; typically associated with infrared radiation and a frequency of 7 × 10⁻⁷ meters to 1× 10⁻³ meters.

processes of change within a system that are related to its entropy and enthalpy.

the study of the relationships between heat, energy, and work in a system.

sets of input/output wires in a switch.

the quality of a tone or sound that is unique from its loudness and pitch and allows one to distinguish between different sound sources.

the energy released by burning 1 US short ton (0.91 metric ton) of coal; equal to 19.49 × 10⁶ BTU or 21.28 × 10¹⁰ joules.

a vocal or musical sound with a specific pitch and loudness.

the tendency of a force to cause an object to rotate, defined mathematically as the rate of change of the object’s angular momentum; also called moment of force.

the sum of all the kinetic and potential energies of an object in a closed system.

the path of a thrown or falling object, such as a baseball.

type of wave that displaces its medium perpendicular to the direction of energy transfer. Ocean waves, for example, move water vertically but transmit energy horizontally across the surface.

also known as lateral magnification; synonymous with linear magnification.

a type of wave wherein the medium is displaced in a direction perpendicular to the movement of energy, as in the case of waves on the surface of water.

the lowest point of a wave from its neutral value.

the number of times that a conductor is wrapped around to form a helical coil.

a mathematical description of the motion in space of two rigid, point-like objects interacting with each other.

describes a sound, or a device that makes use of sound, with a frequency above twenty thousand hertz, the upper limit of human hearing.

the use of ultrasonic vibrations to strengthen metals.

the use of ultrasound to test materials for internal flaws.

a real-time locating system that uses ultrasound to track the location of objects or individuals on small spatial scales.

electromagnetic radiation with more energy than visible light but less than x-rays, in the wavelength range of 4 × 10⁻⁷ to 1 × 10⁻⁷ meters.

the erroneous prediction, based on the laws of classical physics, that a blackbody would emit an infinite amount of energy at short wavelengths, starting around the ultraviolet region.

the idea, proposed by Werner Heisenberg, that one can deter­mine with high precision either the position of a particle at a given time or its mo­mentum, but not both.

the damage caused by ultraviolet radiation when it strikes certain materials.

a subtype of ultraviolet radiation with wavelength under 200 nanometers.

a geometric concept describing both the magnitude of a property and the direction in which it operates, to be fully described, such as velocity or acceleration.

a vector quantity that includes both the speed and the direction of motion.

a vector quantity that describes the rate of displacement over time. The rate of change of position in a specified direction of motion

the uppermost point in a ballistic trajectory.

a darkening or shading of an image’s edges compared to the center of the image.

an image that forms at the point where the paths of rays cross when projected backward from a lens.

electromagnetic radiation that human eyes can see, with a wavelength between 4 × 10⁻⁷ to 7 × 10⁻⁷ meters.

the difference in electric potential between two points, measured in volts; electric current flows naturally from the higher-voltage point to the lower-voltage point.

the space occupied by an object or substance, measured in cubic meters (m³); together with mass, it determines the density of an object and its specific gravity. Alternative units include liters (L) or cubic feet (ft³).

the digital manipulation of an image that mimics distortion and can be used to correct for distortion or to introduce various creative effects.

the SI unit for measuring power (work over time), defined as one joule per second.

a function that describes the quantum state of a system and represents the probability of finding the system in a given state at a given time.

the manner in which a wave travels.

in any wave system, the distance from one point in a wave to the equivalent point in the next wave, typically measured between successive peak values.

the idea that a particle can behave as either a particle or a wave, depending on how and when it is being observed.

interaction between subatomic particles at a short distance that is influenced by the weak nuclear force, one of the four fundamental forces in nature.

the downward force imparted to an object by gravity acting on its mass; measured according to the International System of Units (SI) in newtons, though it is normally expressed in units of mass for everyday objects on Earth.

the use of energy to move an object over a distance by means of the application of force.

a force successfully moving an object, or the successful transfer of energy. The International System of Units unit of work is the joule.

the principle that the work performed on an object is equal to the change in that object’s kinetic energy.

electromagnetic radiation with a wavelength between 1 × 10−10 and 1× 10−8 meters.