A

• absolute zero – theoretically, the lowest obtainable temperature
• acceleration – the rate of change of velocity with respect to time
• adhesion – molecular attraction between two surfaces making contact
• adiabatic – any change in which there is no gain or loss of heat
• alloy – homogenous mixture of two or more metals
• alternating current – the electric current that changes its direction periodically
• ammeter – an instrument for measuring electric current in amperes
• amorphous – solids which have neither definite form nor structure
• ampere – SI unit of electric current, one ampere is the flow of 1 coulomb of charge per second
• amplitude – the maximum absolute value obtained by the disturbance of a wave or by any quantity that varies periodically
• angle of incidence/incidence – the angle that a straight line, ray of light, etc, meeting a surface, makes with that surface at the point of meeting
• angstrom – a unit of length; one =10-10m
• angular momentum – also called moment of momentum, it is the cross product of position vector and momentum
• anisotropic – directionally dependent
• asteroid –  a small rocky body orbiting the sun
• asymptotic – a line that approaches zero without ever actually reaching zero

• atomic mass unit – AMU
• atomic number – the number of protons in an atomic nucleus
• Axis – a straight line about which rotation takes place; straight lines for reference in a graph, usually the x-axis for measuring horizontal displacement and the y-axis for measuring vertical displacement

B

• Barometer – an instrument used to measure atmospheric pressure
• Beta particle – an electron emitted from a nucleus in radioactive decay
• Black body – an ideal body which would absorb all incident radiation and reflect none
• Black hole – the remaining core of a supernova that is so dense that even light cannot

• Boiling – a change from liquid to gas, occurring beneath the surface of the liquid
• Buoyant – upward force of an object immersed in fluid

C

• Calorie – a unit of heat; one calorie = 4.186 joules
• Calorimetry – the measurement of heat changes
• Capacitance– the ratio of charge stored per increase in potential difference
• Capacitor – electrical device used to store charge and energy in the electrical field
• Capillary action – the movement of liquid up a narrow tube as a result of adhesive forces
• Cartesian coordinate system – a system that specifies each point uniquely in a plane by a pair of numerical coordinates
• Catalyst – a substance that increases the rate of a chemical reaction without its self being consumed
• Center of gravity – point at the center of an object’s weight distribution where the force of gravity can be considered to act
• Center of mass – point at the center of an object’s mass distribution where all its mass can be considered to be concentrated
• Centrifugal force – an outward pseudo force acting on a body in a circular motion
• Centripetal force – the radial force required to keep an object moving in a circular path
• Chromatic aberration – the material effect produced by the refraction of different wavelengths of electromagnetic radiation through slightly different angles, resulting in a failure to focus. it causes colored fringes in the images produced by uncorrected lenses
• Circuit – any complete path along which electric charge can flow
• Circuit breaker – an automatic device for stopping the flow of current in an electric circuit as a safety measure
• Cis – describes the isomer in which two substituents both lie on the same side of a double bond
• Coherence length – the propagation distance over which a coherent wave maintains a specified degree of coherence
• Cohesion – the attraction of like molecules
• Combustion – burning in air
• Compound – a substance composed of atoms of two or more elements chemically united in fixed proportions Compression – in mechanics, the act of squeezing material and reducing its volume; in sound, the region of increased pressure in a longitudinal wave
• Concentration – amount of solute relative to the volume of a solution or to the amount of solvent in a solution
• Conductor–  (allow movement)- a substance or medium that conducts heat, light, sound, or especially an electric charge
• Conserved – term applied to physical quantity, such as momentum, energy or electric charge, that remains unchanged during interaction
• Constant – a quantity that is unknown but assumed to have a fixed value in a specified mathematical context
• Constructive interference – a type of interference that occurs at any location along the medium where the two interfering waves have a displacement in the same direction
• Corrosion – the undesirable oxidation of metals
• Cost – work and energy involved
• Coulomb – Si unit of electrical charge
• Critical angle – the smallest possible angle of incidence for which light rays are totally reflected at an interface between substances of different refractive index

• Current density -(J)- the amount of electric current flowing per unit cross-sectional area of a material

D

• Decibel – unit of sound level
• Delta – represents change
• Density – the right ratio of mass to volume
• Deposition – the phase change from gas to solid
• Destructive interference – a type of interference that occurs at any location along the medium where the two interfering waves have a displacement in an opposite direction
• Dielectric – (insulate) – insulating material or a very poor conductor of electric current
• Diffraction – the bending of light around the corners of an object
• Diffraction grating – a plate of glass or metal ruled with very close parallel lines, producing a spectrum by diffraction and interference of light
• Diffuse reflection – reflection from a rough surface
• Diffusion – the mixing of gases
• Dilution – the process of preparing a less concentrated solution from a more concentrated one
• Dimension – a measure of spatial extent, especially with height or length
• Diode – an electronic device that restricts the flow of electrons in a  circuit to one direction
• Diopter – a unit of refractive power that is equal to the reciprocal of the focal length of a given lens
• Dipole – (+/-) – a pair of separated electric charges or magnetic poles of equal magnitude but of opposite sign or polarity
• Dipole moment – a quantitative measure of the polarity of a bond
• Discreet – a finite or countable set of values; not continuous
• Dispersion – the splitting of white light into its component parts
• Displacement field – a vector field which accounts for the effects of free and bound charges within materials
• Distortion – the alteration of the original shape of something, such as an object, image, sound or waveform
• Doppler effect – the apparent change in the frequency of a wave due to relative motion between the source and the observer

E

• Echo – reflection of sound
• Eddy –  changing, curling paths in turbulent flow of a liquid

• Effusion – the escape of a gas from a container into a vacuum
• Elasticity – property of a solid wherein a change in shape is experienced when a deforming force acts on it, with a return to its original shape when the deforming force is removed
• Elastomer – a material that can stretch or bend and then return to its original shape as long as the limits of its elasticity are not exceeded
• Electrical resistance – the property to oppose the flow of current
• electrode – a conductor through which electricity enters or leaves an object
• Electromotive force (EMF) – a source of energy that can cause a current to flow in an electrical circuit or device
• Ellipse – a closed, symmetric curve shaped like an oval
• Error propagation – escape
• Ether – hypothetical invisible medium that was formerly thought to be required for the propagation of electromagnetic waves, and thought to fill space throughout the universe
• Extremum – maximum or minimum value of a function

F

• Farad – SI unit of electrical capacitance
• Fiber optics – a technology that uses glass threads to transmit data
• Fluid – anything that flows, in particular any liquid or gas
• Flux – the number of field lines penetrating a surface
• Focal length – the distance between the lens and the image sensor when the subject is in focus
• Focal plane – the plane perpendicular to the axis of a lens or mirror and passes through the focal point
• Focal point – for a converging lens or a concave mirror, the point at which rays of light parallel to the principle axis converge
• Frequency – for a vibrating body or medium, the number of vibrations per unit time; for a wave, the number of crests that pass a particular point per unit time. Frequency is measured in Hertz
• Friction – a force that acts to resist the relative motion of objects or materials that are in contact
• Fulcrum – pivot point of a lever

G

• Galvanometer – an instrument for detecting electrical current
• Gas – phase of matter beyond the liquid phase, wherein molecules fill whatever space is available to them, taking no definite shape
• Generator – (make electricity) – machine that converts one form of energy into another
• Gradient – (upside down delta) – the rate at which a physical quantity, such as temperature or pressure, changes in response to changes in a given variable
• Gravitation – an attraction between objects due to mass
• Gravity – the gravitational attraction at the surface of a planet or other celestial body
• Grounding – (open 4’s interlocking) – the process of removing the excess charge on an object by means of the transfer of electrons between it and another object

H

• Half-life – the time during which half the number of atoms in the element disintegrate
• Hysteresis – the lag in response exhibited by a body in reacting to changes in the forces, especially in magnetic forces affecting it

I

• Impulse – the product of force and time for which force acts, also equal to the change in momentum
• In vacuo –  in a vacuum or in isolation
• Incidence – the intersection of a line or something moving in a straight line, such as a beam of light with a surface
• index of refraction (IOR) – the speed of light in a vacuum divided by the speed of light in the medium
• induction – the process by which electrical or magnetic properties are transferred, without physical contact from one circuit or body to another
• inductor  – a passive electronic component that stores energy in the form of a magnetic field
• Inertia – the sluggishness or apparent resistance of an object to change its state of motion. Mass is the measure of inertia.
• Infrared – electromagnetic waves of frequencies lower than the red of visible light
•  insulator – (prevent movement) – any of various substances that block or retard the flow of electrical or thermal currents
• internal resistance – the resistance within a battery, or other voltage source that causes a drop in the source voltage when there is a current

J

• joule – (j) – SI unit of work or energy
• junction – a connection between two or more conductors

L

• laser – a device which creates a beam of light where all of the photons are in a coherent state
• Linear momentum – product of the mass and the velocity of an object. Also called momentum
• Logarithmic – exponential

M

• Magnetic – any object that has the ability to attract objects made of iron or other magnetic substances
• magnetic dipole moment – measure of the magnetic strength of a magnet or current-carrying coil
• magnetic induction – magnetization induced by proximity to a magnetic field
• magnetism/magnetic field – (B) – the properties of attraction common to magnets
• magnetization –  – process of making a substance temporarily or permanently magnetic
• mass spectrometer – an apparatus for separating isotopes, molecules and molecular fragments according to mass
• mean-free path – (MFP) the distance that a molecule travels between collisions
• Mechanical energy – energy due to the position or the movement of something; potential or kinetic energy or a combination of both
• Microwaves – electromagnetic waves with frequencies greater than radio waves but less than infrared waves
•  mirage –  a naturally occurring optical phenomenon in which light rays are bent to produce a displaced image of distant objects or the sky
• moment – a combination of physical quantity and a distance
• Momentum – the product of a mass and velocity of a body, it is a measure of the quantity of motion in a body
• monopole – a magnetic pole considered in isolation
•  muon – an unstable subatomic particle
•  mutual induction – the magnetic field generated by a coil of wire induces voltage in an adjacent coil of wire

N

• naught – the digit zero
• neutrino – a neutral subatomic particle with a mass close to zero, rarely reacting with normal matter
• Newton – Si unit of force
•  Nonpolar molecule  – a molecule with polar bonds but having a symmetrical molecular structure; or a molecule containing atoms of equal or almost equal eletronegativities
• Normal force – component of support force perpendicular to a supporting surface. For an object resting on a horizontal surface, it is the upward force that balances the object
• Nuclear fission – the splitting a heavy nucleus into more stable lighter nuclei with an accompanying release of
• Nuclear fusion – the combination of two lighter nuclei to form a heavier nucleus with an accompanying energy

O

• oblate (of a sphere) – flattened at the poles
• Ohm – a unit of resistance
•  Optics – the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it
• Oscillation – same as vibration; a repeating to and fro motion about an equilibrium position
• Out of phase – a term applied to two waves for which the crest of one wave arrives coincident with the trough of a second wave; their effects tend to cancel each other

P

• parabola – a conic section formed by the intersection of a cone by a plane parallel to its side

• Parallax – apparent displacement of an object when viewed by an observer from two different positions; often used to calculate the distance of stars
• permativity – the measure of the resistance that is encountered when forming an electric field in a medium; to store electrical energy in an electrical field
• Photon – the particle associated with light
• polarize – (stretch) – a property of waves that can oscillate with more than one orientation
• polarizer – an optical filter that passes light of a specific polarization and blocks waves of other polarization
•  positron – a particle of matter with the same mass as an electron, but positive charge
• potential drop – electrical potential difference
• potential energy – the energy an object has because of its position rather than its motion
• prism – a transparent solid body often having triangular bases used for dispersing light into a spectrum or for reflecting rays of light
•  propagate – to cause (an organism) to multiply by any process of natural reproduction from the parent stock; to reproduce (itself) its kind, etc.

• Pulley – wheel that acts as a lever, used to change the direction of a force. A pulley or system of pulleys can multiply forces

Q

• quadratic – involving the second and no higher power of a unknown quantity or variable
• quantize – to restrict (a variable quantity) to discreet values rather than to a continuous set of values

• Quark – one of the two classes of elementary particles

R

• Radiation – energy transmitted by electromagnetic waves
• Radioactive – term applied to an atom having an unstable nucleus that can spontaneously emit a particle and become the nucleus of another element
• Reflection – the bouncing back of a wave from a boundary
• Refraction – the bending of light from its straight line path when it travels from one medium to another
• repel – push an object away with an electrical force
• resistivity – a material’s opposition to the flow of electric current; measured in ohms

• Reverberation – the persistence of a sound, as in an echo, due to multiple reflections
• Rotation – spinning motion that occurs when an object rotated about an axis located within the object (usually an axis through its center of mass)

S

• Saturated – term applied to a substance, such as air, that contains a maximum amount of another substance, such as water vapor, at a given temperature and pressure
• scalar – a quantity having only magnitude, not direction

• Scatter – to absorb sound or light and re-emit it in all directions
• Simple harmonic motion – (SHO) vibratory or periodic motion, like that of a pendulum
• Specific heat – the amount of heat energy required to increase the temperature of one gram of a substance by one
• specular reflection – reflection from a smooth surface
• speed of light – (C)

• Static friction – the force between two objects at relative rest by virtue of contact that tends to oppose sliding
• super conductor –  a substance capable of becoming super conducting at sufficiently low temperatures; an element when cooled to near absolute zero dramatically lose all electrical resistance
• superposition – the overlapping of waves

• Surface tension – tendency of the surface of a liquid to contract in area and thus behave like a stretched elastic membrane

T

• Tangential speed – linear speed along a closed path
• Tangential velocity – component of velocity tangent to the trajectory of a projectile
• tensor – an array of components that are functions of coordinates of a space

• Terminal speed – speed obtained by an object wherein the resistive forces, often air resistance, counterbalance the driving forces, so motion is without acceleration
• Terminal velocity – terminal speed, together with the direction of motion (down for falling objects)
• terminal voltage – the voltage at the terminals of an electrical device
• Tesla – an SI unit for measuring magnetic field

• toriod – a coil of insulated or enameled wire

• Torque – product of force and lever-arm distance which tends to produce rotational acceleration
• total internal reflection – a phenomenon which occurs when a propagating wave strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface

• Transformer – device for increasing or decreasing voltage or transferring electric power from one coil of wire to another by means of electromagnetic induction

U

• Ultraviolet – (UV) – electromagnetic waves of frequencies higher than those of violet light

V

• Vacuum – absence of matter; void
• Vaporization – the process of a phase change from liquid to vapor
• Vector – arrow whose length represents the magnitude of a quantity and whose direction represents the direction of the quantity

• virtual image – an image formed when the outgoing rays from a point on an object always diverge

• Voltage – electrical “pressure” or a measure of electrical potential difference
• voltmeter – an instrument used for measuring electrical potential difference between two points in an electrical circuit

• Volume – quantity of space an object occupies

W

• wavelength – (WL) the distance, measured in the direction of propagation of a wave between two successive points in the wave that are characterized by the same phase of oscillation
• Weber – (WB) – unit of magnetic flux