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    Example and Directions
    Words (or words that have the same definition) The definition is case sensitive (Optional) Image to display with the definition [Not displayed in Glossary, only in pop-up on pages] (Optional) Caption for Image (Optional) External or Internal Link (Optional) Source for Definition
    (Eg. "Genetic, Hereditary, DNA ...") (Eg. "Relating to genes or heredity") The infamous double helix CC-BY-SA; Delmar Larsen
    Glossary Entries



    Image Caption Link Source
    width of the central peak angle between the minimum for \(\displaystyle m=1\) and \(\displaystyle m=−1\)       OpenStax
    two-slit diffraction pattern diffraction pattern of two slits of width a that are separated by a distance d is the interference pattern of two point sources separated by d multiplied by the diffraction pattern of a slit of width a       OpenStax
    resolution ability, or limit thereof, to distinguish small details in images       OpenStax
    Rayleigh criterion two images are just-resolvable when the center of the diffraction pattern of one is directly over the first minimum of the diffraction pattern of the other       OpenStax
    missing order interference maximum that is not seen because it coincides with a diffraction minimum       OpenStax
    holography process of producing holograms with the use of lasers       OpenStax
    hologram three-dimensional image recorded on film by lasers; the word hologram means entire picture (from the Greek word holo, as in holistic)       OpenStax
    diffraction limit fundamental limit to resolution due to diffraction       OpenStax
    diffraction grating large number of evenly spaced parallel slits       OpenStax
    diffraction bending of a wave around the edges of an opening or an obstacle       OpenStax
    destructive interference for a single slit occurs when the width of the slit is comparable to the wavelength of light illuminating it       OpenStax
    Bragg planes families of planes within crystals that can give rise to X-ray diffraction       OpenStax
    coherent waves waves are in phase or have a definite phase relationship       OpenStax
    fringes bright and dark patterns of interference       OpenStax
    incoherent waves have random phase relationships       OpenStax
    interferometer instrument that uses interference of waves to make measurements       OpenStax
    monochromatic light composed of one wavelength only       OpenStax
    Newton’s rings circular interference pattern created by interference between the light reflected off two surfaces as a result of a slight gap between them       OpenStax
    order integer m used in the equations for constructive and destructive interference for a double slit       OpenStax
    principal maximum brightest interference fringes seen with multiple slits       OpenStax
    secondary maximum bright interference fringes of intensity lower than the principal maxima       OpenStax
    aberration distortion in an image caused by departures from the small-angle approximation       OpenStax
    accommodation use of the ciliary muscles to adjust the shape of the eye lens for focusing on near or far objects       OpenStax
    angular magnification ratio of the angle subtended by an object observed with a magnifier to that observed by the naked eye       OpenStax
    apparent depth depth at which an object is perceived to be located with respect to an interface between two media       OpenStax
    Cassegrain design arrangement of an objective and eyepiece such that the light-gathering concave mirror has a hole in the middle, and light then is incident on an eyepiece lens       OpenStax
    charge-coupled device (CCD) semiconductor chip that converts a light image into tiny pixels that can be converted into electronic signals of color and intensity       OpenStax
    coma similar to spherical aberration, but arises when the incoming rays are not parallel to the optical axis       OpenStax
    compound microscope microscope constructed from two convex lenses, the first serving as the eyepiece and the second serving as the objective lens       OpenStax
    concave mirror spherical mirror with its reflecting surface on the inner side of the sphere; the mirror forms a “cave”       OpenStax
    converging (or convex) lens lens in which light rays that enter it parallel converge into a single point on the opposite side       OpenStax
    convex mirror spherical mirror with its reflecting surface on the outer side of the sphere       OpenStax
    curved mirror mirror formed by a curved surface, such as spherical, elliptical, or parabolic       OpenStax
    diverging (or concave) lens lens that causes light rays to bend away from its optical axis       OpenStax
    eyepiece lens or combination of lenses in an optical instrument nearest to the eye of the observer       OpenStax
    far point furthest point an eye can see in focus       OpenStax
    farsightedness (or hyperopia) visual defect in which near objects appear blurred because their images are focused behind the retina rather than on the retina; a farsighted person can see far objects clearly but near objects appear blurred       OpenStax
    first focus or object focus object located at this point will result in an image created at infinity on the opposite side of a spherical interface between two media       OpenStax
    focal length distance along the optical axis from the focal point to the optical element that focuses the light rays       OpenStax
    focal plane plane that contains the focal point and is perpendicular to the optical axis       OpenStax
    focal point for a converging lens or mirror, the point at which converging light rays cross; for a diverging lens or mirror, the point from which diverging light rays appear to originate       OpenStax
    image distance distance of the image from the central axis of the optical element that produces the image       OpenStax
    linear magnification ratio of image height to object height       OpenStax
    magnification ratio of image size to object size       OpenStax
    near point closest point an eye can see in focus       OpenStax
    nearsightedness (or myopia) visual defect in which far objects appear blurred because their images are focused in front of the retina rather than on the retina; a nearsighted person can see near objects clearly but far objects appear blurred       OpenStax
    net magnification (MnetMnet) of the compound microscope is the product of the linear magnification of the objective and the angular magnification of the eyepiece       OpenStax
    Newtonian design arrangement of an objective and eyepiece such that the focused light from the concave mirror was reflected to one side of the tube into an eyepiece       OpenStax
    object distance

    distance of the object from the central axis of the optical element that produces its image

    objective lens nearest to the object being examined.       OpenStax
    optical axis axis about which the mirror is rotationally symmetric; you can rotate the mirror about this axis without changing anything       OpenStax
    optical power (P) inverse of the focal length of a lens, with the focal length expressed in meters. The optical power P of a lens is expressed in units of diopters D; that is, \(\displaystyle 1D=1/m=1m^{−1}\)       OpenStax
    plane mirror plane (flat) reflecting surface       OpenStax
    ray tracing technique that uses geometric constructions to find and characterize the image formed by an optical system       OpenStax
    real image image that can be projected onto a screen because the rays physically go through the image       OpenStax
    second focus or image focus for a converging interface, the point where a bundle of parallel rays refracting at a spherical interface; for a diverging interface, the point at which the backward continuation of the refracted rays will converge between two media will focus       OpenStax
    simple magnifier (or magnifying glass) converging lens that produces a virtual image of an object that is within the focal length of the lens       OpenStax
    small-angle approximation approximation that is valid when the size of a spherical mirror is significantly smaller than the mirror’s radius; in this approximation, spherical aberration is negligible and the mirror has a well-defined focal point       OpenStax
    spherical aberration distortion in the image formed by a spherical mirror when rays are not all focused at the same point       OpenStax
    thin-lens approximation assumption that the lens is very thin compared to the first image distance       OpenStax
    vertex point where the mirror’s surface intersects with the optical axis       OpenStax
    virtual image image that cannot be projected on a screen because the rays do not physically go through the image, they only appear to originate from the image       OpenStax
    birefringent refers to crystals that split an unpolarized beam of light into two beams       OpenStax
    Brewster’s angle angle of incidence at which the reflected light is completely polarized       OpenStax
    Brewster’s law \(\displaystyle tanθ_b=\frac{n_2}{n_1}\), where \(\displaystyle n_1\) is the medium in which the incident and reflected light travel and \(\displaystyle n_2\) is the index of refraction of the medium that forms the interface that reflects the light       OpenStax
    corner reflector object consisting of two (or three) mutually perpendicular reflecting surfaces, so that the light that enters is reflected back exactly parallel to the direction from which it came       OpenStax
    critical angle incident angle that produces an angle of refraction of 90°       OpenStax
    direction of polarization direction parallel to the electric field for EM waves       OpenStax
    dispersion spreading of light into its spectrum of wavelengths       OpenStax
    geometric optics part of optics dealing with the ray aspect of light       OpenStax
    horizontally polarized oscillations are in a horizontal plane       OpenStax
    Huygens’s principle every point on a wave front is a source of wavelets that spread out in the forward direction at the same speed as the wave itself; the new wave front is a plane tangent to all of the wavelets       OpenStax
    index of refraction for a material, the ratio of the speed of light in a vacuum to that in a material       OpenStax
    law of reflection angle of reflection equals the angle of incidence       OpenStax
    law of refraction when a light ray crosses from one medium to another, it changes direction by an amount that depends on the index of refraction of each medium and the sines of the angle of incidence and angle of refraction       OpenStax
    Malus’s law where \(\displaystyle I_0\) is the intensity of the polarized wave before passing through the filter       OpenStax
    optically active substances that rotate the plane of polarization of light passing through them       OpenStax
    polarization attribute that wave oscillations have a definite direction relative to the direction of propagation of the wave       OpenStax
    polarized refers to waves having the electric and magnetic field oscillations in a definite direction       OpenStax
    ray straight line that originates at some point       OpenStax
    refraction changing of a light ray’s direction when it passes through variations in matter       OpenStax
    total internal reflection phenomenon at the boundary between two media such that all the light is reflected and no refraction occurs       OpenStax
    unpolarized refers to waves that are randomly polarized       OpenStax
    vertically polarized oscillations are in a vertical plane       OpenStax
    wave optics part of optics dealing with the wave aspect of light       OpenStax
    classical (Galilean) velocity addition method of adding velocities when \(\displaystyle v<<c\); velocities add like regular numbers in one-dimensional motion: \(\displaystyle u=v+u'\), where v is the velocity between two observers, u is the velocity of an object relative to one observer, and \(\displaystyle u'\) is the velocity relative to the other observer       OpenStax
    event occurrence in space and time specified by its position and time coordinates (x, y, z, t) measured relative to a frame of reference       OpenStax
    first postulate of special relativity laws of physics are the same in all inertial frames of reference       OpenStax
    Galilean relativity if an observer measures a velocity in one frame of reference, and that frame of reference is moving with a velocity past a second reference frame, an observer in the second frame measures the original velocity as the vector sum of these velocities       OpenStax
    Galilean transformation relation between position and time coordinates of the same events as seen in different reference frames, according to classical mechanics       OpenStax
    inertial frame of reference reference frame in which a body at rest remains at rest and a body in motion moves at a constant speed in a straight line unless acted on by an outside force       OpenStax
    length contraction decrease in observed length of an object from its proper length \(\displaystyle L_0\) to length L when its length is observed in a reference frame where it is traveling at speed v       OpenStax
    Lorentz transformation relation between position and time coordinates of the same events as seen in different reference frames, according to the special theory of relativity       OpenStax
    Michelson-Morley experiment investigation performed in 1887 that showed that the speed of light in a vacuum is the same in all frames of reference from which it is viewed       OpenStax
    proper length \(\displaystyle L_0\); the distance between two points measured by an observer who is at rest relative to both of the points; for example, earthbound observers measure proper length when measuring the distance between two points that are stationary relative to Earth       OpenStax
    proper time \(\displaystyle Δτ\) is the time interval measured by an observer who sees the beginning and end of the process that the time interval measures occur at the same location       OpenStax
    relativistic kinetic energy kinetic energy of an object moving at relativistic speeds       OpenStax
    relativistic momentum \(\displaystyle \vec{p}\), the momentum of an object moving at relativistic velocity; \(\displaystyle \vec{p}=γm\vec{u}\)       OpenStax
    lativistic velocity addition method of adding velocities of an object moving at a relativistic speeds       OpenStax
    rest energy energy stored in an object at rest: \(\displaystyle E_0=mc^2\)       OpenStax
    rest frame frame of reference in which the observer is at rest       OpenStax
    rest mass mass of an object as measured by an observer at rest relative to the object       OpenStax
    second postulate of special relativity light travels in a vacuum with the same speed c in any direction in all inertial frames       OpenStax
    special theory of relativity theory that Albert Einstein proposed in 1905 that assumes all the laws of physics have the same form in every inertial frame of reference, and that the speed of light is the same within all inertial frames       OpenStax
    speed of light ultimate speed limit for any particle having mass       OpenStax
    time dilation lengthening of the time interval between two events when seen in a moving inertial frame rather than the rest frame of the events (in which the events occur at the same location)       OpenStax
    total energy sum of all energies for a particle, including rest energy and kinetic energy, given for a particle of mass m and speed u by \(\displaystyle E=γmc^2\), where \(\displaystyle γ=\frac{1}{\sqrt{1−\frac{u^2}{c^2}}}\)       OpenStax
    world line path through space-time       OpenStax
    absorber any object that absorbs radiation       OpenStax
    absorption spectrum wavelengths of absorbed radiation by atoms and molecules       OpenStax
    Balmer formula describes the emission spectrum of a hydrogen atom in the visible-light range       OpenStax
    Balmer series spectral lines corresponding to electron transitions to/from the \(\displaystyle n=2\) state of the hydrogen atom, described by the Balmer formula       OpenStax
    blackbody perfect absorber/emitter       OpenStax
    blackbody radiation radiation emitted by a blackbody       OpenStax
    Bohr radius of hydrogen radius of the first Bohr’s orbit       OpenStax
    Bohr’s model of the hydrogen atom first quantum model to explain emission spectra of hydrogen       OpenStax
    Brackett series spectral lines corresponding to electron transitions to/from the \(\displaystyle n=4\) state       OpenStax
    Compton effect the change in wavelength when an X-ray is scattered by its interaction with some materials       OpenStax
    Compton shift difference between the wavelengths of the incident X-ray and the scattered X-ray       OpenStax
    Compton wavelength physical constant with the value \(\displaystyle λ_c=2.43pm\)       OpenStax
    cut-off frequency frequency of incident light below which the photoelectric effect does not occur       OpenStax
    cut-off wavelength wavelength of incident light that corresponds to cut-off frequency       OpenStax
    Davisson–Germer experiment historically first electron-diffraction experiment that revealed electron waves       OpenStax
    de Broglie wave matter wave associated with any object that has mass and momentum       OpenStax
    de Broglie’s hypothesis of matter waves particles of matter can behave like waves       OpenStax
    double-slit interference experiment Young’s double-slit experiment, which shows the interference of waves       OpenStax
    electron microscopy microscopy that uses electron waves to “see” fine details of nano-size objects       OpenStax
    emission spectrum wavelengths of emitted radiation by atoms and molecules       OpenStax
    emitter any object that emits radiation       OpenStax
    energy of a photon quantum of radiant energy, depends only on a photon’s frequency       OpenStax
    energy spectrum of hydrogen set of allowed discrete energies of an electron in a hydrogen atom       OpenStax
    excited energy states of the H atom energy state other than the ground state       OpenStax
    Fraunhofer lines dark absorption lines in the continuum solar emission spectrum       OpenStax
    ground state energy of the hydrogen atom energy of an electron in the first Bohr orbit of the hydrogen atom       OpenStax
    group velocity velocity of a wave, energy travels with the group velocity       OpenStax
    Heisenberg uncertainty principle sets the limits on precision in simultaneous measurements of momentum and position of a particle       OpenStax
    Humphreys series spectral lines corresponding to electron transitions to/from the \(\displaystyle n=6\) state       OpenStax
    hydrogen-like atom ionized atom with one electron remaining and nucleus with charge \(\displaystyle +Ze\)       OpenStax
    inelastic scattering scattering effect where kinetic energy is not conserved but the total energy is conserved       OpenStax
    ionization energy energy needed to remove an electron from an atom       OpenStax
    ionization limit of the hydrogen atom ionization energy needed to remove an electron from the first Bohr orbit       OpenStax
    Lyman series spectral lines corresponding to electron transitions to/from the ground state       OpenStax
    nuclear model of the atom heavy positively charged nucleus at the center is surrounded by electrons, proposed by Rutherford       OpenStax
    Paschen series spectral lines corresponding to electron transitions to/from the \(\displaystyle n=3\) state       OpenStax
    Pfund series spectral lines corresponding to electron transitions to/from the \(\displaystyle n=5\) state       OpenStax
    photocurrent in a circuit, current that flows when a photoelectrode is illuminated       OpenStax
    photoelectric effect emission of electrons from a metal surface exposed to electromagnetic radiation of the proper frequency       OpenStax
    photoelectrode in a circuit, an electrode that emits photoelectrons       OpenStax
    photoelectron electron emitted from a metal surface in the presence of incident radiation       OpenStax
    photon particle of light       OpenStax
    Planck’s hypothesis of energy quanta energy exchanges between the radiation and the walls take place only in the form of discrete energy quanta       OpenStax
    postulates of Bohr’s model three assumptions that set a frame for Bohr’s model       OpenStax
    power intensity energy that passes through a unit surface per unit time       OpenStax
    propagation vector vector with magnitude \(\displaystyle 2π/λ\) that has the direction of the photon’s linear momentum       OpenStax
    quantized energies discrete energies; not continuous       OpenStax
    quantum number index that enumerates energy levels       OpenStax
    quantum phenomenon in interaction with matter, photon transfers either all its energy or nothing       OpenStax
    quantum state of a Planck’s oscillator any mode of vibration of Planck’s oscillator, enumerated by quantum number       OpenStax
    reduced Planck’s constant Planck’s constant divided by \(\displaystyle 2π\)       OpenStax
    Rutherford’s gold foil experiment first experiment to demonstrate the existence of the atomic nucleus       OpenStax
    Rydberg constant for hydrogen physical constant in the Balmer formula       OpenStax
    Rydberg formula experimentally found positions of spectral lines of hydrogen atom       OpenStax
    scattering angle angle between the direction of the scattered beam and the direction of the incident beam       OpenStax
    Stefan–Boltzmann constant physical constant in Stefan’s law       OpenStax
    stopping potential in a circuit, potential difference that stops photocurrent       OpenStax
    wave number magnitude of the propagation vector       OpenStax
    wave quantum mechanics theory that explains the physics of atoms and subatomic particles       OpenStax
    wave-particle duality particles can behave as waves and radiation can behave as particles       OpenStax
    work function energy needed to detach photoelectron from the metal surface       OpenStax
    α-particle doubly ionized helium atom       OpenStax
    α-ray beam of \(\displaystyle α\)-particles (alpha-particles)       OpenStax
    β-ray beam of electrons       OpenStax
    γ-ray beam of highly energetic photons       OpenStax
    anti-symmetric function odd function       OpenStax
    Born interpretation states that the square of a wave function is the probability density       OpenStax
    complex function function containing both real and imaginary parts       OpenStax
    Copenhagen interpretation states that when an observer is not looking or when a measurement is not being made, the particle has many values of measurable quantities, such as position       OpenStax
    correspondence principle in the limit of large energies, the predictions of quantum mechanics agree with the predictions of classical mechanics       OpenStax
    energy levels states of definite energy, often represented by horizontal lines in an energy “ladder” diagram       OpenStax
    energy quantum number index that labels the allowed energy states       OpenStax
    energy-time uncertainty principle energy-time relation for uncertainties in the simultaneous measurements of the energy of a quantum state and of its lifetime       OpenStax
    even function in one dimension, a function symmetric with the origin of the coordinate system       OpenStax
    expectation value average value of the physical quantity assuming a large number of particles with the same wave function       OpenStax
    field emission electron emission from conductor surfaces when a strong external electric field is applied in normal direction to conductor’s surface       OpenStax
    ground state energy lowest energy state in the energy spectrum       OpenStax
    Heisenberg’s uncertainty principle places limits on what can be known from a simultaneous measurements of position and momentum; states that if the uncertainty on position is small then the uncertainty on momentum is large, and vice versa       OpenStax
    infinite square well potential function that is zero in a fixed range and infinitely beyond this range       OpenStax
    momentum operator operator that corresponds to the momentum of a particle       OpenStax
    nanotechnology technology that is based on manipulation of nanostructures such as molecules or individual atoms to produce nano-devices such as integrated circuits       OpenStax
    normalization condition requires that the probability density integrated over the entire physical space results in the number one       OpenStax
    odd function in one dimension, a function antisymmetric with the origin of the coordinate system       OpenStax
    position operator operator that corresponds to the position of a particle       OpenStax
    potential barrier potential function that rises and falls with increasing values of position       OpenStax
    principal quantum number energy quantum number       OpenStax
    probability density square of the particle’s wave function       OpenStax
    quantum dot small region of a semiconductor nanocrystal embedded in another semiconductor nanocrystal, acting as a potential well for electrons       OpenStax
    quantum tunneling phenomenon where particles penetrate through a potential energy barrier with a height greater than the total energy of the particles       OpenStax
    resonant tunneling tunneling of electrons through a finite-height potential well that occurs only when electron energies match an energy level in the well, occurs in quantum dots       OpenStax
    resonant-tunneling diode quantum dot with an applied voltage bias across it       OpenStax
    scanning tunneling microscope (STM) device that utilizes quantum-tunneling phenomenon at metallic surfaces to obtain images of nanoscale structures       OpenStax
    Schrӧdinger’s time-dependent equation equation in space and time that allows us to determine wave functions of a quantum particle       OpenStax
    Schrӧdinger’s time-independent equation equation in space that allows us to determine wave functions of a quantum particle; this wave function must be multiplied by a time-modulation factor to obtain the time-dependent wave function       OpenStax
    standing wave state stationary state for which the real and imaginary parts of Ψ(x,t)Ψ(x,t) oscillate up and down like a standing wave (often modeled with sine and cosine functions)       OpenStax
    state reduction hypothetical process in which an observed or detected particle “jumps into” a definite state, often described in terms of the collapse of the particle’s wave function       OpenStax
    stationary state state for which the probability density function, \(\displaystyle |Ψ(x,t)|^2\), does not vary in time       OpenStax
    time-modulation factor factor \(\displaystyle e^{−iωt}\) that multiplies the time-independent wave function when the potential energy of the particle is time independent       OpenStax
    transmission probability also called tunneling probability, the probability that a particle will tunnel through a potential barrier       OpenStax
    tunnel diode electron tunneling-junction between two different semiconductors       OpenStax
    tunneling probability also called transmission probability, the probability that a particle will tunnel through a potential barrier       OpenStax
    wave function function that represents the quantum state of a particle (quantum system)       OpenStax
    wave function collapse equivalent to state reduction       OpenStax
    wave packet superposition of many plane matter waves that can be used to represent a localized particle       OpenStax
    angular momentum orbital quantum number (l) quantum number associated with the orbital angular momentum of an electron in a hydrogen atom       OpenStax
    angular momentum projection quantum number (m) quantum number associated with the z-component of the orbital angular momentum of an electron in a hydrogen atom       OpenStax
    atomic orbital region in space that encloses a certain percentage (usually 90%) of the electron probability       OpenStax
    Bohr magneton magnetic moment of an electron, equal to \(\displaystyle 9.3×10^{−24}J/T\) or \(\displaystyle 5.8×10^{−5}eV/T\)       OpenStax
    braking radiation radiation produced by targeting metal with a high-energy electron beam (or radiation produced by the acceleration of any charged particle in a material)       OpenStax
    chemical group group of elements in the same column of the periodic table that possess similar chemical properties       OpenStax
    coherent light light that consists of photons of the same frequency and phase       OpenStax
    covalent bond chemical bond formed by the sharing of electrons between two atoms       OpenStax
    electron configuration representation of the state of electrons in an atom, such as \(\displaystyle 1s^22s^1\) for lithium       OpenStax
    fine structure detailed structure of atomic spectra produced by spin-orbit coupling       OpenStax
    fluorescence radiation produced by the excitation and subsequent, gradual de-excitation of an electron in an atom       OpenStax
    hyperfine structure detailed structure of atomic spectra produced by spin-orbit coupling       OpenStax
    ionic bond chemical bond formed by the electric attraction between two oppositely charged ions       OpenStax
    laser coherent light produced by a cascade of electron de-excitations       OpenStax
    magnetic orbital quantum number another term for the angular momentum projection quantum number       OpenStax
    magnetogram pictoral representation, or map, of the magnetic activity at the Sun’s surface       OpenStax
    metastable state state in which an electron “lingers” in an excited state       OpenStax
    monochromatic light that consists of photons with the same frequency       OpenStax
    Moseley plot plot of the atomic number versus the square root of X-ray frequency       OpenStax
    Moseley’s law relationship between the atomic number and X-ray photon frequency for X-ray production       OpenStax
    Orbital magnetic dipole moment measure of the strength of the magnetic field produced by the orbital angular momentum of the electron       OpenStax
    Pauli’s exclusion principle no two electrons in an atom can have the same values for all four quantum numbers \(\displaystyle (n,l,m,ms)\)       OpenStax
    population inversion condition in which a majority of atoms contain electrons in a metastable state       OpenStax
    principal quantum number (n) quantum number associated with the total energy of an electron in a hydrogen atom       OpenStax
    radial probability density function function use to determine the probability of a electron to be found in a spatial interval in r       OpenStax
    selection rules rules that determine whether atomic transitions are allowed or forbidden (rare)       OpenStax
    spin projection quantum number (\(\displaystyle m_s\)) quantum number associated with the z-component of the spin angular momentum of an electron       OpenStax
    spin quantum number (s) quantum number associated with the spin angular momentum of an electron       OpenStax
    spin-flip transitions atomic transitions between states of an electron-proton system in which the magnetic moments are aligned and not aligned       OpenStax
    spin-orbit coupling interaction between the electron magnetic moment and the magnetic field produced by the orbital angular momentum of the electron       OpenStax
    stimulated emission when a photon of energy triggers an electron in a metastable state to drop in energy emitting an additional photon       OpenStax
    transition metal element that is located in the gap between the first two columns and the last six columns of the table of elements that contains electrons that fill the d subshell       OpenStax
    valence electron electron in the outer shell of an atom that participates in chemical bonding       OpenStax
    Zeeman effect splitting of energy levels by an external magnetic field       OpenStax
    acceptor impurity atom substituted for another in a semiconductor that results in a free electron       OpenStax
    amplifier electrical device that amplifies an electric signal       OpenStax
    base current current drawn from the base n-type material in a transistor       OpenStax
    BCS theory theory of superconductivity based on electron-lattice-electron interactions       OpenStax
    body-centered cubic (BCC) crystal structure in which an ion is surrounded by eight nearest neighbors located at the corners of a unit cell       OpenStax
    breakdown voltage in a diode, the reverse bias voltage needed to cause an avalanche of current       OpenStax
    collector current current drawn from the collector p-type material       OpenStax
    conduction band above the valence band, the next available band in the energy structure of a crystal       OpenStax
    Cooper pair coupled electron pair in a superconductor       OpenStax
    covalent bond bond formed by the sharing of one or more electrons between atoms       OpenStax
    critical magnetic field maximum field required to produce superconductivity       OpenStax
    critical temperature maximum temperature to produce superconductivity       OpenStax
    density of states number of allowed quantum states per unit energy       OpenStax
    depletion layer region near the p-n junction that produces an electric field       OpenStax
    dissociation energy amount of energy needed to break apart a molecule into atoms; also, total energy per ion pair to separate the crystal into isolated ions       OpenStax
    donor impurity atom substituted for another in a semiconductor that results in a free electron hole       OpenStax
    doping alteration of a semiconductor by the substitution of one type of atom with another       OpenStax
    drift velocity average velocity of a randomly moving particle       OpenStax
    electric dipole transition transition between energy levels brought by the absorption or emission of radiation       OpenStax
    electron affinity energy associated with an accepted (bound) electron       OpenStax
    electron number density number of electrons per unit volume       OpenStax
    energy band nearly continuous band of electronic energy levels in a solid       OpenStax
    energy gap gap between energy bands in a solid       OpenStax
    equilibrium separation distance distance between atoms in a molecule       OpenStax
    exchange symmetry how a total wave function changes under the exchange of two electrons       OpenStax
    face-centered cubic (FCC) crystal structure in which an ion is surrounded by six nearest neighbors located at the faces at the faces of a unit cell       OpenStax
    Fermi energy largest energy filled by electrons in a metal at \(\displaystyle T=0K\)       OpenStax
    Fermi factor number that expresses the probability that a state of given energy will be filled       OpenStax
    Fermi temperature effective temperature of electrons with energies equal to the Fermi energy       OpenStax
    forward bias configuration diode configuration that results in high current       OpenStax
    free electron model model of a metal that views electrons as a gas       OpenStax
    hole unoccupied states in an energy band       OpenStax
    hybridization change in the energy structure of an atom in which energetically favorable mixed states participate in bonding       OpenStax
    impurity atom acceptor or donor impurity atom       OpenStax
    impurity band new energy band create by semiconductor doping       OpenStax
    ionic bond bond formed by the Coulomb attraction of a positive and negative ions       OpenStax
    junction transistor electrical valve based on a p-n-p junction       OpenStax
    lattice regular array or arrangement of atoms into a crystal structure       OpenStax
    Madelung constant constant that depends on the geometry of a crystal used to determine the total potential energy of an ion in a crystal       OpenStax
    majority carrier free electrons (or holes) contributed by impurity atoms       OpenStax
    minority carrier free electrons (or holes) produced by thermal excitations across the energy gap       OpenStax
    n-type semiconductor doped semiconductor that conducts electrons       OpenStax
    p-n junction junction formed by joining p- and n-type semiconductors       OpenStax
    p-type semiconductor doped semiconductor that conducts holes       OpenStax
    polyatomic molecule molecule formed of more than one atom       OpenStax
    repulsion constant experimental parameter associated with a repulsive force between ions brought so close together that the exclusion principle is important       OpenStax
    reverse bias configuration diode configuration that results in low current       OpenStax
    rotational energy level energy level associated with the rotational energy of a molecule       OpenStax
    selection rule rule that limits the possible transitions from one quantum state to another       OpenStax
    semiconductor solid with a relatively small energy gap between the lowest completely filled band and the next available unfilled band       OpenStax
    simple cubic basic crystal structure in which each ion is located at the nodes of a three-dimensional grid       OpenStax
    type I superconductor superconducting element, such as aluminum or mercury       OpenStax
    type II superconductor superconducting compound or alloy, such as a transition metal or an actinide series element       OpenStax
    valence band highest energy band that is filled in the energy structure of a crystal       OpenStax
    van der Waals bond bond formed by the attraction of two electrically polarized molecules       OpenStax
    vibrational energy level energy level associated with the vibrational energy of a molecule       OpenStax
    acceptor impurity atom substituted for another in a semiconductor that results in a free electron       OpenStax
    activity magnitude of the decay rate for radioactive nuclides       OpenStax
    alpha (α) rays one of the types of rays emitted from the nucleus of an atom as alpha particles       OpenStax
    alpha decay radioactive nuclear decay associated with the emission of an alpha particle       OpenStax
    antielectrons another term for positrons       OpenStax
    antineutrino antiparticle of an electron’s neutrino in β decay       OpenStax
    atomic mass total mass of the protons, neutrons, and electrons in a single atom       OpenStax
    atomic mass unit unit used to express the mass of an individual nucleus, where 1u=1.66054×10−27 kg       OpenStax
    atomic nucleus tightly packed group of nucleons at the center of an atom       OpenStax
    atomic number number of protons in a nucleus       OpenStax
    becquerel (Bq) SI unit for the decay rate of a radioactive material, equal to 1 decay/second       OpenStax
    beta (ββ) rays one of the types of rays emitted from the nucleus of an atom as beta particles       OpenStax
    beta decay radioactive nuclear decay associated with the emission of a beta particle       OpenStax
    binding energy (BE) energy needed to break a nucleus into its constituent protons and neutrons       OpenStax
    binding energy per nucleon (BEN) energy need to remove a nucleon from a nucleus       OpenStax
    breeder reactor reactor that is designed to make plutonium       OpenStax
    carbon-14 dating method to determine the age of formerly living tissue using the ratio \(\displaystyle ^{14}C/^{12}C\)       OpenStax
    chart of the nuclides graph comprising stable and unstable nuclei       OpenStax
    critical mass minimum mass required of a given nuclide in order for self-sustained fission to occur       OpenStax
    criticality condition in which a chain reaction easily becomes self-sustaining       OpenStax
    curie (Ci) unit of decay rate, or the activity of 1 g of \(\displaystyle ^{226}Ra\), equal to \(\displaystyle 3.70×10^{10}Bq\)       OpenStax
    daughter nucleus nucleus produced by the decay of a parent nucleus       OpenStax
    decay process by which an individual atomic nucleus of an unstable atom loses mass and energy by emitting ionizing particles       OpenStax
    decay constant quantity that is inversely proportional to the half-life and that is used in equation for number of nuclei as a function of time       OpenStax
    decay series series of nuclear decays ending in a stable nucleus       OpenStax
    fission splitting of a nucleus       OpenStax
    gamma (γγ) rays one of the types of rays emitted from the nucleus of an atom as gamma particles       OpenStax
    gamma decay radioactive nuclear decay associated with the emission of gamma radiation       OpenStax
    half-life time for half of the original nuclei to decay (or half of the original nuclei remain)       OpenStax
    high dose dose of radiation greater than 1 Sv (100 rem)       OpenStax
    isotopes nuclei having the same number of protons but different numbers of neutrons       OpenStax
    lifetime average time that a nucleus exists before decaying       OpenStax
    liquid drop model model of nucleus (only to understand some of its features) in which nucleons in a nucleus act like atoms in a drop       OpenStax
    low dose dose of radiation less than 100 mSv (10 rem)       OpenStax
    mass defect difference between the mass of a nucleus and the total mass of its constituent nucleons       OpenStax
    mass number number of nucleons in a nucleus       OpenStax
    moderate dose dose of radiation from 0.1 Sv to 1 Sv (10 to 100 rem)       OpenStax
    neutrino subatomic elementary particle which has no net electric charge       OpenStax
    neutron number number of neutrons in a nucleus       OpenStax
    nuclear fusion process of combining lighter nuclei to make heavier nuclei       OpenStax
    nuclear fusion reactor nuclear reactor that uses the fusion chain to produce energy       OpenStax
    nucleons protons and neutrons found inside the nucleus of an atom       OpenStax
    nucleosynthesis process of fusion by which all elements on Earth are believed to have been created       OpenStax
    nuclide nucleus       OpenStax
    parent nucleus original nucleus before decay       OpenStax
    positron electron with positive charge       OpenStax
    positron emission tomography (PET) tomography technique that uses \(\displaystyle β^+\) emitters and detects the two annihilation \(\displaystyle γ\) rays, aiding in source localization       OpenStax
    proton-proton chain combined reactions that fuse hydrogen nuclei to produce He nuclei       OpenStax
    radiation dose unit (rad) ionizing energy deposited per kilogram of tissue       OpenStax
    radioactive dating application of radioactive decay in which the age of a material is determined by the amount of radioactivity of a particular type that occurs       OpenStax
    radioactive decay law describes the exponential decrease of parent nuclei in a radioactive sample       OpenStax
    radioactive tags special drugs (radiopharmaceuticals) that allow doctors to track movement of other drugs in the body       OpenStax
    radioactivity spontaneous emission of radiation from nuclei       OpenStax
    radiopharmaceutical compound used for medical imaging       OpenStax
    radius of a nucleus radius of a nucleus is defined as \(\displaystyle r=r_0A^{1/3}\)       OpenStax
    relative biological effectiveness (RBE) number that expresses the relative amount of damage that a fixed amount of ionizing radiation of a given type can inflict on biological tissues       OpenStax
    roentgen equivalent man (rem) dose unit more closely related to effects in biological tissue       OpenStax
    sievert (Sv) SI equivalent of the rem       OpenStax
    single-photon-emission computed tomography (SPECT) tomography performed with \(\displaystyle γ\)-emitting radiopharmaceuticals       OpenStax
    strong nuclear force force that binds nucleons together in the nucleus       OpenStax
    transuranic element element that lies beyond uranium in the periodic table       OpenStax
    antiparticle subatomic particle with the same mass and lifetime as its associated particle, but opposite electric charge       OpenStax
    baryon number baryon number has the value \(B=+1\) for baryons, \(–1\) for antibaryons, and 0 for all other particles and is conserved in particle interactions       OpenStax
    baryons group of three quarks       OpenStax
    Big Bang rapid expansion of space that marked the beginning of the universe       OpenStax
    boson particle with integral spin that are symmetric on exchange       OpenStax
    color property of particles and that plays the same role in strong nuclear interactions as electric charge does in electromagnetic interactions       OpenStax
    cosmic microwave background radiation (CMBR) thermal radiation produced by the Big Bang event       OpenStax
    cosmology study of the origin, evolution, and ultimate fate of the universe       OpenStax
    dark energy form of energy believed to be responsible for the observed acceleration of the universe       OpenStax
    dark matter matter in the universe that does not interact with other particles but that can be inferred by deflection of distance star light       OpenStax
    electroweak force unification of electromagnetic force and weak-nuclear force interactions       OpenStax
    exchange symmetry property of a system of indistinguishable particles that requires the exchange of any two particles to be unobservable       OpenStax
    fermion particle with half-integral spin that is antisymmetric on exchange       OpenStax
    Feynman diagram space-time diagram that describes how particles move and interact       OpenStax
    fundamental force one of four forces that act between bodies of matter: the strong nuclear, electromagnetic, weak nuclear, and gravitational forces       OpenStax
    gluon particle that that carry the strong nuclear force between quarks within an atomic nucleus       OpenStax
    grand unified theory theory of particle interactions that unifies the strong nuclear, electromagnetic, and weak nuclear forces       OpenStax
    hadron a meson or baryon       OpenStax
    Hubble’s constant constant that relates speed and distance in Hubble’s law       OpenStax
    Hubble’s law relationship between the speed and distance of stars and galaxies       OpenStax
    lepton a fermion that participates in the electroweak force       OpenStax
    lepton number electron-lepton number \(L_e\), the muon-lepton number \(L_μ\), and the tau-lepton number \(L_τ\) are conserved separately in every particle interaction       OpenStax
    mesons a group of two quarks       OpenStax
    nucleosynthesis creation of heavy elements, occurring during the Big Bang       OpenStax
    particle accelerator machine designed to accelerate charged particles; this acceleration is usually achieved with strong electric fields, magnetic fields, or both       OpenStax
    particle detector detector designed to accurately measure the outcome of collisions created by a particle accelerator; particle detectors are hermetic and multipurpose       OpenStax
    positron antielectron       OpenStax
    quantum chromodynamics (QCD) theory that describes strong interactions between quarks       OpenStax
    quantum electrodynamics (QED) theory that describes the interaction of electrons with photons       OpenStax
    quark a fermion that participates in the electroweak and strong nuclear force       OpenStax
    redshift lengthening of the wavelength of light (or reddening) due to cosmological expansion       OpenStax
    Standard Model model of particle interactions that contains the electroweak theory and quantum chromodynamics (QCD)       OpenStax
    strangeness particle property associated with the presence of a strange quark       OpenStax
    strong nuclear force relatively strong attractive force that acts over short distances (about \(10^{−15}) m) responsible for binding protons and neutrons together in atomic nuclei       OpenStax
    synchrotron circular accelerator that uses alternating voltage and increasing magnetic field strengths to accelerate particles to higher and higher energies       OpenStax
    synchrotron radiation high-energy radiation produced in a synchrotron accelerator by the circular motion of a charged beam       OpenStax
    theory of everything a theory of particle interactions that unifies all four fundamental forces       OpenStax
    virtual particle particle that exists for too short of time to be observable       OpenStax
    W and Z boson particle with a relatively large mass that carries the weak nuclear force between leptons and quarks       OpenStax
    weak nuclear force relative weak force (about \(10^{−6}\) the strength of the strong nuclear force) responsible for decays of elementary particles and neutrino interactions       OpenStax
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