Diffraction and Interfraction Flashcards
what is diffraction
bending of waves as they pass the edge of an obstacle or through an aperture (a gap in a barrier)
what does amount of diffraction depend on
wavelength of the wave
width of the object or aperture
waves with low wavelength diffract little + vice versa
wavelength relationship with diffraction
the longer the wavelength, the more is diffracts and bend around objects.
the shorter a wavelength (higher frequency), the less it diffracts and moves around other objects
applications of high frequency sounds
as high frequency sounds are diffracted less, their direction relative to the listener can be pinpointed easily
how is ultrasound frequency used
they are used for sonar and medical imaging as they have 20kHz frequencies. they are also used for echolocation by bats and dolphins
superposition principle
matter takes up space and cannot share that space with other matter
waves can be in the same region or same medium at the same time
this resulting wave is the sum of the individual waves - superposition principle
what is superposition important for
producing complex sounds when multiple waves combine and can produce waves with varying amplitudes.
what is inerference
results of superposition
two waves can reinforce each other, resulitng in a wave with higher amplitude (constructive interference)
two waves can counteract each other, resulting in a wave of lower amplitude (destructive interference)
transverse waves - interference
two waves can push particles in the same direction (constructive) or opposite direction (destructive)
longitudinal waves - interference
the two waves can compress the same parts of the medium (constructive) or compress the other’s rarefactions (destructive)
what is a beat
when two sound waves of different frequencies are added together, they alternate between constructive and destructive intereference to form a wave with a regular pulsation known as a beat.
formula for beat
frequency of beat = frequence of wave2 - frequency of wave1
what are beats used for
tune musical instruments
how do noise cancelling headphones work
noise cancelling headphones record outside noise, and then produce a wave that is exactly in the opposite phase
the superposition of the unwanted noise with the anti noise wave creates destructive interference and it cancels out and allows you to hear only devices sound.
what is resonance
when an object is exposed to vibrations equal to their resonant frequency. the vibration from one object causes a strong vibration in another. if the amplitude of the vibration becomes too great, the object can be destroyed
when does resonance occur
when the driving frequency matches the natural frequency
what happens when resonance occurs
amplitude of the resonating object’s oscilations will increase dramatically
the max possible energy from the driving frequency source is transferred to the object.
