particles of the material vibrate parallel as the motion of the wave
example of longitudinal wave
sound
transverse waves
the particles of the material vibrate perpendicular to the direction the wave is travelling
example of transverse waves
light
frequency
number of waves to pass a point in one second
period
the time it takes for one wave to pass a point
in order for waves to interact with each other they must have the same frequency and wavelength
when two waves meet, they combine to produce an interference pattern
coherence
same wavelength
same frequency
fixed phase difference
same velocity
phase
a measure of how "in step" waves are
if phase difference is zero
waves are coherent
constructive interference
waves meet crest to crest and trough to trough.
are in phase
destructive interference
waves meet crest to trough and are 180 degrees out of phase
what happens at constructive interference
produce a larger crest
what happens at destructive interference
produce nowave at that point
the difference in distance is known as the path difference
bright fringe
constructive interference
dark fringe
destructive interference
maxima
constructive interference
minima
destructive interference
the central maximum has zero path difference
increasing number of slits
increases the distance between maxima
increasing distance to the screen
increases the distance between maxima
increasing the wavelength
increases the distance between maxima
wavelength of red light
700 nm
wavelength of green light
550 nm
wavelength of blue light
500 nm
wavelength of violet light
400 nm
prism
only one spectrum produced
red deviated least
violet deviated most
less widely spaced
grating
many spectra produced
red deviated most
violet deviated least
less intense
more spread out
central image same colour as the source
why is light from a grating less intense
energy divided between several spectra
the name given to the spreading of light is known as diffraction
When light passes through a grating the wavefronts on the opposite side overlap resulting in a pattern being formed. The name given to this patterned phenomenon is: