waves, optics and modern physics unit 2

terms and definitions from unit 2

beat frequency

frequency of beats produced by sound waves that differ in frequency

beats

constructive and destructive interference of two or more frequencies of sound

doppler effect

alteration in the observed frequency of a sound due to motion of either the source or the observer

doppler shift

actual change in frequency due to relative motion of source and observer

fundamental

the lowest-frequency resonance

harmonics

the term used to refer collectively to the fundamental and its overtones

hearing

perception of sound

loudness

perception of sound intensity

notes

basic unit of music with specific names, combined to generate tunes

overtones

all resonant frequencies higher than the fundamental

phon

numerical unit of loudness

pitch

perception of the frequency of a sound

sound

traveling pressure wave that may be periodic; the wave can be modeled as a pressure wave or as an oscillation of molecules

sound intensity level

unitless quantity telling you the level of sound relative to a fixed standard

sound pressure level

ratio of the pressure amplitude to a reference pressure

timbre

number and relative intensity of multiple sound frequencies

transducer

device that converts energy of a signal into a measurable energy form

coherent waves

waves are in phase or have a definite phase relationship

incoherent wave

waves have random phase relationships

monochromatic light

light composed of one wavelength only

order of interference

integer m used in the equations for constructive and destructive interference for a double slit

interference fringes

bright and dark patterns of interference

principal maxima

brightest interference fringe seen with multiple slits

secondary maximum

bright interference fringes of intensity lower than the principal maxima

diffraction

bending of a wave around the edges of an opening or an obstacle

destructive interference for a single slit

occurs when the width of the slit is comparable to the wavelength of light illuminating it

width of the central peak

angle between the minimum for m=1 and m=-1

missing order

interference maximum that is not seen because it coincides with a diffraction minimum

diffraction grating

large number of evenly spaced parallel slits

resolution

ability, or limit thereof, to distinguish small details in images

diffraction limit

fundamental limit to resolution due to diffraction

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