Huygens’ Principle And Wave Interference

Question 1

What is attenuations?

Answer 1

Weakening of sound as it travels

Question 2

What is a sine wave?

Answer 2

A symmetric wave that describes the movement of something with time

Question 3

What are Huygens’ Sources?

Answer 3

The idea that ultrasound beams is actually created by many waves each emitted by their own source. Which is Huygens sources

Question 4

What are Huygens’ Wavelets?

Answer 4

Waves emitted from each source.

Question 5

What does changing the size of the sources do for the wavelets?

Answer 5

These wavelets diverge from the source and the rate of divergence depends on as the size of the source

Question 6

What is divergence?

Answer 6

The spreading of the beam as it travels from the source

Question 7

If we have a larger source what does that do to the divergence?

Answer 7

The larger the source of sound the less divergence there is

Question 8

When does diffraction occur?

Answer 8

Occurs after a beam with planar wave fronts pass through a small aperture

Question 9

What is Huygens’ Principle?

Answer 9

Each point source creates its own sound wave or beam. Basically, multiple wavelets from many sources together form a new wave-front

Question 10

Why is Huygens’ principle important?

Answer 10

It is important to consider during the designing of probes.

Question 11

How are typical probes designed?

Answer 11

1.They generally have a array of multiple small elements or crystal mounted on the transducer face.
2. Each crystal is its own separate source and all of the sound sources together create the larger beam

Question 12

What is interference?

Answer 12

When two or more waves interact

Question 13

What is sensitivity?

Answer 13

The ability to pick up weak echoes

Question 14

What is an example of interference?

Answer 14

Adding of the motion from one wave to that of another

Question 15

What can interference be categorized as?

Answer 15

Constructive or destructive

Question 16

What is constructive interference?

Answer 16

When two waves are “in phase” and the contribution of each wave results in an increase in amplitude and intensity

Question 17

What is destructive interference?

Answer 17

When two waves are “out of phase” and the contribution of each wave results in a decrease in amplitude and intensity or they may simply cancel each other out

Question 18

What is beat frequency?

Answer 18

When two waves are neither completely in phase nor out of phase

Question 19

How are Doppler signals detected in ultrasound? (What do we use?)

Answer 19

We use beat frequency

Question 20

Interference effects what?

Answer 20

The uniformity of the beams intensity and amplification throughout the ultrasonic field.

Question 21

What does changes in intensity do?

Answer 21

Effects the sensitivity of the beam

Question 22

Interferences also gives what in terms of the beam?

Answer 22

Gives the shape of the beam responsible for the natural focusing of the beam

Question 23

Why is beam shape important?

Answer 23

Important in terms of considering the image resolution

Question 24

When do standing waves occur?

Answer 24

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

Question 25

What are nodes?

Answer 25

Points of minimum fluctuation and are points of low pressure

Question 26

What are anti nodes?

Answer 26

Points of maximum fluctuation and are points of high pressure

Question 27

Standing wave can give rise to what?

Answer 27

Areas of enhanced or decreased amplitude