Huygens Principle And Wave Interference Flashcards
A symmetric wave that describes the movement of something with time
Sine wave
A higher amplitude means either louder, stronger, more power OR quieter, weaker, less power ?
louder, stronger, more power
If waves are inverse to each other are they IN phase or OUT of phase
Out of phase
The point sources in which each individual wave is emitted from is called?
Huygens sources
The waves that are emitted from each source are called what?
Huygens wavelets
Wavelets diverge from the source but the rate in which divergence occurs depends on what?
The size of the source
A LARGER source has more or less divergence
Less
A SMALLER source has less or more divergence
More
The spreading of the beam as it travels away from the source is called
Divergence
When a beam with a planar wavefront passes through a small hole (aperture) what is this
Diffraction
Simply describe Huygens principle
Each point source creates its own sound wave/beam and that multiple wavelets together form a new wavefront
Is Huygens principle important in the design of probes
Yes
How is Huygens principle important in probe design
Multiple crystals are on the front of the transducer face, and each crystals sound beams form together to create the larger beam
When two or more waves interact this is called?
Interference
Adding the motion of one wave to another is classified as
Interference
What two categories are there for interference
Constructive
Destructive
When two waves are “in phase” the contributions of each wave results in an increase in amplitude and intensity. What type of interference is this
Constructive
When two waves are “out of phase” and the contributions of each wave results in a decrease in amplitude and intensity what type of inter fence is this
Destructive
Destructive interference causes an increase or decrease in amplitude and intensity
Decrease
Constructive intensity results in an increase or decrease in intensity and amplitude
Increase
Is is possible for waves to completely cancel each other out in destructive interference
Yes
When two waves or neither “in phase” or “out of phase” what is created
Beat frequency is produced
Beat frequency is how —— signals are detected in ultrasound
Doppler
Uniformity of the beam intensity and amplification throughout the ultrasonic field is effected by what
Interference
Changes in intensity can effect the ——of the beam
Sensitivity
Interference is responsible for doing what to the beam
Interference gives the beam a shape and is responsible for the natural focusing of the beam
The shape of the beam is important when considering the image ——
Resolution
When two waves propagate in the same medium but in opposite directions what occurs
Standing waves
When the two waves in standing waves are added together some parts of the amplitude is —— and other parts are ——
Zero and doubled
In standing waves the minimum points of fluctuation that are points of low pressure are called
Nodes
In standing waves points of maximum fluctuation and are points of high pressure are called
Anti-nodes
Are standing waves able to give rise to areas of enhanced and decreased amplitudes
Yes
Are nodes or anti nodes more intense/brighter
Anti nodes are more intense and brighter
Nodes are darker
How are changes in acoustic variables represented visually
By a sine wave
When two waves are equal in amplitude, and frequency and are 180 degrees out of phase with each other what happens
They completely cancel each other out
What is the difference between diffraction and divergence
Diffraction - spreading of beams as it passes through a small opening
Divergence - spreading of beam as it travels
What are the individual sources of sound found in a transducer array referring to when relating to Huygens principle
Huygens sources and the Huygens wavelets that come from the individual sources
State Huygens principle
Each point source creates its sound wave/beam
A wave front is made up of individual point sources of sound
Explain how a standing wave is produced
When two waves traveling in opposite directions interfere
Nodes are located where on a standing wave
In the middle where waves intersect
Where are antinodes located on a standing wave
On the troughs/crests of waves
Explain the significance of a standing wave in relation to the potential effects that it can have on observed ultrasound images
Areas of nodes - result in areas of darkness on the screen (amplitude of zero)
Areas of antinodes - create areas of brightness (bigger amplitudes)
