Huygens Principle And Wave Interference

Question 1

A symmetric wave that describes the movement of something with time

Answer 1

Sine wave

Question 2

A higher amplitude means either louder, stronger, more power OR quieter, weaker, less power ?

Answer 2

louder, stronger, more power

Question 3

If waves are inverse to each other are they IN phase or OUT of phase

Answer 3

Out of phase

Question 4

The point sources in which each individual wave is emitted from is called?

Answer 4

Huygens sources

Question 5

The waves that are emitted from each source are called what?

Answer 5

Huygens wavelets

Question 6

Wavelets diverge from the source but the rate in which divergence occurs depends on what?

Answer 6

The size of the source

Question 7

A LARGER source has more or less divergence

Answer 7

Less

Question 8

A SMALLER source has less or more divergence

Answer 8

More

Question 9

The spreading of the beam as it travels away from the source is called

Answer 9

Divergence

Question 10

When a beam with a planar wavefront passes through a small hole (aperture) what is this

Answer 10

Diffraction

Question 11

Simply describe Huygens principle

Answer 11

Each point source creates its own sound wave/beam and that multiple wavelets together form a new wavefront

Question 12

Is Huygens principle important in the design of probes

Answer 12

Yes

Question 13

How is Huygens principle important in probe design

Answer 13

Multiple crystals are on the front of the transducer face, and each crystals sound beams form together to create the larger beam

Question 14

When two or more waves interact this is called?

Answer 14

Interference

Question 15

Adding the motion of one wave to another is classified as

Answer 15

Interference

Question 16

What two categories are there for interference

Answer 16

Constructive

Destructive

Question 17

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

Answer 17

Constructive

Question 18

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

Answer 18

Destructive

Question 19

Destructive interference causes an increase or decrease in amplitude and intensity

Answer 19

Decrease

Question 20

Constructive intensity results in an increase or decrease in intensity and amplitude

Answer 20

Increase

Question 21

Is is possible for waves to completely cancel each other out in destructive interference

Answer 21

Yes

Question 22

When two waves or neither “in phase” or “out of phase” what is created

Answer 22

Beat frequency is produced

Question 23

Beat frequency is how —— signals are detected in ultrasound

Answer 23

Doppler

Question 24

Uniformity of the beam intensity and amplification throughout the ultrasonic field is effected by what

Answer 24

Interference

Question 25

Changes in intensity can effect the ——of the beam

Answer 25

Sensitivity

Question 26

Interference is responsible for doing what to the beam

Answer 26

Interference gives the beam a shape and is responsible for the natural focusing of the beam

Question 27

The shape of the beam is important when considering the image ——

Answer 27

Resolution

Question 28

When two waves propagate in the same medium but in opposite directions what occurs

Answer 28

Standing waves

Question 29

When the two waves in standing waves are added together some parts of the amplitude is —— and other parts are ——

Answer 29

Zero and doubled

Question 30

In standing waves the minimum points of fluctuation that are points of low pressure are called

Answer 30

Nodes

Question 31

In standing waves points of maximum fluctuation and are points of high pressure are called

Answer 31

Anti-nodes

Question 32

Are standing waves able to give rise to areas of enhanced and decreased amplitudes

Answer 32

Yes

Question 33

Are nodes or anti nodes more intense/brighter

Answer 33

Anti nodes are more intense and brighter Nodes are darker

Question 34

How are changes in acoustic variables represented visually

Answer 34

By a sine wave

Question 35

When two waves are equal in amplitude, and frequency and are 180 degrees out of phase with each other what happens

Answer 35

They completely cancel each other out

Question 36

What is the difference between diffraction and divergence

Answer 36

Diffraction - spreading of beams as it passes through a small opening Divergence - spreading of beam as it travels

Question 37

What are the individual sources of sound found in a transducer array referring to when relating to Huygens principle

Answer 37

Huygens sources and the Huygens wavelets that come from the individual sources

Question 38

State Huygens principle

Answer 38

Each point source creates its sound wave/beam | A wave front is made up of individual point sources of sound

Question 39

Explain how a standing wave is produced

Answer 39

When two waves traveling in opposite directions interfere

Question 40

Nodes are located where on a standing wave

Answer 40

In the middle where waves intersect

Question 41

Where are antinodes located on a standing wave

Answer 41

On the troughs/crests of waves

Question 42

Explain the significance of a standing wave in relation to the potential effects that it can have on observed ultrasound images

Answer 42

Areas of nodes - result in areas of darkness on the screen (amplitude of zero) Areas of antinodes - create areas of brightness (bigger amplitudes)