Waves Flashcards
what is a progressive wave
a wave that travels through matter (or in some cases a vacuum) and transfers energy from A to B but not matter
equation for velocity of a wave
v=f(lamda)
equation for frequency
f=1/T
what is intensity proportional to
amplitude^2
what are coherent waves
waves emitted from two sources that have constant phase difference
when two waves superpose what happens
at points in phase, constructive interference
at points out of phase, destructive interference
how are stationary waves created
reflected wave superposes
antiphase points create nodes with zero displacement
in phrase points create antinodes with max displacement
distance between node and antinode = half wavelength
when two waves interfere to create interference patterns, where are maxima and minima formed?
when path difference is an integer multiple of wavelength then a maxima is formed
when path difference in (n+1/2)(lamda) then a minima is formed
path and phase difference at central maxima
0 and 0
path and phase difference at first order minima
1/2 lamda and pi
path and phase difference at first order maxima
lamda and 2pi
what is the fundamental frequency
the minimum frequency for a standing/stationary wave
equation for youngs double slit experiment
lamda=ax/D a=slit separation D=distance between slits and board showing interference pattern x=separation between fringes
in reflection what angle equals what angle
angle of incidence = angle of reflection
equation for refractive index
n=c/v c=speed of light 3X10^8
v= speed of light through material
refraction law equation
n1sin(x1)=n2sin(x2)
x=angle between ray and normal
what is refraction
occurs when a wave changes direction as it changes speed when passing from one medium to another
what is diffraction
the spreading out of a wave when it passes through a gap or around an obstacle.
when does maximum diffraction occur
when the gap is the same size as the wavelength of the wave
what is polarisation
when particles oscillate in one plane/direction
what is the intensity of a progressive wave?
the radiant power passing through a surface per unit area
equation for intensity
I=P/A
equation for intensity radiated from a sphere
I=P/4(pi)r^2
order of EM
Red midgets interfere very usually xylophone gigs
radio, micro, infra, visible, ultra, xray, gamma
in this order how does frequency and wavelength change
frequency increases
wavelength decreases
wavelength of radio waves
10^6 to 10^-1
wavelength of microwaves
10^-1 to 10^-3
wavelength of infrared
10^-3 to 700nm
wavelength of visible
700nm to 400nm
wavelength of ultraviolet
400nm to 10^-8
wavelength of xray
10^-8 to 10^-13
wavelength of gamma
10^-10 to 10^-16
equation for frequency of em
f=c/lamda
conditions for total internal reflection
light must be travelling in a medium with a higher refractive index and strike a boundary with a medium of lower refractive index
angle at which it meets boundary must be bigger than the critical angle
equation to find critical angle
sinc=1/n
total internal reflection critical angle with prism
sinc=n2/n1
