# Glossary


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Glossary Entries

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Definition

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

OpenStax
objective lens nearest to the object being examined.       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
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
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