Huygens' Principle and Wave Interference

Question 1

what is a sine wave

Answer 1

a wave that is symmetrical and describes the movement of something with time

Question 2

Huygens’ sources

Answer 2

point sources that create a wave

Question 3

Huygens’ wavelets

Answer 3

the waves emitted from each source

Question 4

wavelets diverge from the source and the rate of divergence depends on the ___ of the source (_____= more divergence)

Answer 4

size
smaller

Question 5

divergence

Answer 5

the spreading of the beam as it travels from the source

Question 6

the _____ the source of sound, the less divergence there is

Answer 6

larger

Question 7

diffraction occurs

Answer 7

after a beam with planar wave fronts pass through an aperature

Question 8

Huygens’ principle

Answer 8

is that each point source creates its own sound wave or beam

Question 9

multiple _____ from many sources together form a new ____

Answer 9

wavelets
wave front

Question 10

Huygens’ principle effects probe design why

Answer 10

typically probes have multiple small crystals mounted on transducer face each with a separate source where all sources form a larger beam together

(impacts sensitivity/res)

Question 11

interference occurs

Answer 11

when 2 or more waves interact

Question 12

interference is the ____ of the motion from one wave to that of another

Answer 12

adding

Question 13

interference 2 categories

Answer 13

constructive
destrcutive

Question 14

constructive interference (occurs/results)

Answer 14

occurs when two waves are “in phase”
contribution of each wave results in an increase in amp/intensity

Question 15

destructive interference (occurs/results)

Answer 15

occurs when two waves are “out of phase”
contribution of both results in an decrease in amp/intensity or cancel out

Question 16

when two waves are neither completely in phase nor out of phase a ______ is produced

Answer 16

beat frequency

Question 17

beat frequency

Answer 17

occurs when two waves are neither completely in phase nor out of phase

Question 17

changes in intensity can effect the ____ of the beam

Answer 17

sensitivity

Question 17

what does beat frequency have to do with ultrasound

Answer 17

how doppler signals are detected in ultrasound (send out on F, get a different F back)

Question 18

interference effects the ____ of the beams intensity and amplification throughout the ______

Answer 18

uniformity
ultrasonic field

Question 19

interference gives the beam a ____ responsible for the ______ of the beam

Answer 19

shape
natural focusing

Question 20

beam shape is also important when considering the image ______

Answer 20

resolution

Question 21

standing waves occur/results

Answer 21

when two waves propagate in the same medium but in opposite directions resulting in some points where amplitude is zero and others where amp is doubled

Question 22

nodes

Answer 22

points of minimum fluctuation and are points of low pressure (smallest difference in wave amp)

Question 23

anti-nodes

Answer 23

the points of maximum fluctuation and are points of high pressure (biggest difference in wave amp)

Question 24

standing waves can give rise to areas of ____ or _____ amplitude

Answer 24

enhanced decreased

Question 25

All points on a wave front are sources of secondary waves

Answer 25

Hyugens' principle

Question 26

A vibration of a system in which some particular points remain fixed while others between them vibrate with the maximum amplitude

Answer 26

standing wave

Question 27

Several wavelets traveling together in a medium create a:

Answer 27

wave front

Question 28

Waves spread out as a result of passing through a narrow aperture

Answer 28

diffraction

Question 29

A symmetrical representation of the movement of something over time

Answer 29

sine wave

Question 30

Two or more waves added together where the resultant amplitude is greater than the original

Answer 30

constructive interference

Question 31

The sound wave emitted from each point source that contribute to the overall wavefront

Answer 31

HUYGENs WAVELETS

Question 32

When two or more waves interfere and are not completely in or out of phase

Answer 32

beat freqeuncy

Question 33

Two or more waves added together where the resultant amplitude is less than the original

Answer 33

destructive interference

Question 34

Individual sources of sound that result in a wavefront when they interfere

Answer 34

Huygens' sources

Question 35

The fixed points of amplitude as the result of a standing wave

Answer 35

nodes

Question 36

What is the result when two waves of equal amplitude, frequency and are 180 degrees out of phase interfere with one another?

Answer 36

total destructive interference

Question 37

Explain the significance of a standing wave in relation to the potential effects that can be observed on an ultrasound image

Answer 37

the areas of nodes can result in areas of darkness on the screen where areas of antinodes can create areas of brightness

Question 38

How does Huygens' Principle apply to transducer construction and design?

Answer 38

Understanding the way that the wavelets from the probe interact allow the ability to alter the shape of the beam for the purpose of steering and focusing. This will impact the sensitivity and resolution of the image.