# Diffraction and Interfraction Flashcards

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1
Q

what is diffraction

A

bending of waves as they pass the edge of an obstacle or through an aperture (a gap in a barrier)

2
Q

what does amount of diffraction depend on

A

wavelength of the wave
width of the object or aperture

waves with low wavelength diffract little + vice versa

3
Q

wavelength relationship with diffraction

A

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

4
Q

applications of high frequency sounds

A

as high frequency sounds are diffracted less, their direction relative to the listener can be pinpointed easily

5
Q

how is ultrasound frequency used

A

they are used for sonar and medical imaging as they have 20kHz frequencies. they are also used for echolocation by bats and dolphins

6
Q

superposition principle

A

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

7
Q

what is superposition important for

A

producing complex sounds when multiple waves combine and can produce waves with varying amplitudes.

8
Q

what is inerference

A

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)

9
Q

transverse waves - interference

A

two waves can push particles in the same direction (constructive) or opposite direction (destructive)

10
Q

longitudinal waves - interference

A

the two waves can compress the same parts of the medium (constructive) or compress the other’s rarefactions (destructive)

11
Q

what is a beat

A

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.

12
Q

formula for beat

A

frequency of beat = frequence of wave2 - frequency of wave1

13
Q

what are beats used for

A

tune musical instruments

14
Q

how do noise cancelling headphones work

A

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.

15
Q

what is resonance

A

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

16
Q

when does resonance occur

A

when the driving frequency matches the natural frequency

17
Q

what happens when resonance occurs

A

amplitude of the resonating object’s oscilations will increase dramatically

the max possible energy from the driving frequency source is transferred to the object.