Interference and Diffraction Flashcards
what does the energy of a wave depend on?
its frequency and amplitude
do longer or shorter wavelengths diffract more?
longer
when does the most diffraction occur?
when the gap and the wavelength are a similar size
what does it mean if two waves are coherent?
they have the same speed, frequency, wavelength and have a constant phases relationship.
what is constructive interference?
when two sets of waves meet in phase (matching crests and troughs)
two crests meet to produce a larger crest
what is destructive interference?
two sets of waves meet out of phase (180 degrees)
a crest and a trough combine to cancel each other out and produce no wave (only if amplitudes are equal)
real life example of destructive interference
noise cancelling headphones
what are areas of constructive interference called?
maximum
what are areas of destructive interference called?
minimum
what is the path difference at the central-zeroth order maximum
zero
what is the path difference in areas of constructive interference
zero or a whole number
what is the path difference in areas of destructive interference
an odd number of half wavelengths (1/2,3/2,5/2 etc.)
equation for path difference at maximum
S2P-S1p=m lambda
equation for path difference at minimum
S2P-S1P= (m+1/2) lambda
what does m tell you?
how many wavelengths one wave travels more than the other