Ultrasound

This lesson covers:

  1. What 'ultrasound' is, and how it's produced
  2. The reflection and refraction of ultrasound at the boundary of two materials
  3. The uses of ultrasound in medical imaging, quality checking, and sonar

Ultrasound is:

Sound with frequencies below human hearing (below 20 Hz)

Sound with frequencies above human hearing (above 20,000 Hz)

0

/

1

Bats naturally produce ultrasound for:

(Select all that apply)

Echolocation

Communication

Scaring away predators

0

/

2

Ultrasound can be produced using a:

Light

Microphone

Speaker

0

/

1

Ultrasound is:

Safe

Harmful sound vibrations

Harmful radiation

0

/

1

Diagram showing ultrasound reflecting off boundaries between mediums of different densities.

thickness / loudness / time


Ultrasound reflects off of the boundaries between mediums of different densities.


The taken for ultrasound to bounce back to the receiver can be used to calculate the of the medium.

time
thickness

0

/

2

Diagram showing ultrasound waves reflecting off a crack in a solid material.

reflect / cracks / solid


Ultrasound can be used to check for in products. The ultrasound would off of the crack and be detected.

cracks
solid
reflect

0

/

3

distance / sonar / boats


Ultrasound is used as by and submarines. By reflecting the ultrasound off the sea floor, we can calculate the from the sea floor. 

sonar
boats
distance

0

/

3

Illustration of a submarine emitting an ultrasound pulse towards the seafloor with a speed of 1500 m/s and a return time of 4 seconds.

Ultrasound travels at 1500 m/s in seawater.


It takes 4 seconds before for a pulse of ultrasound emitted from the submarine towards the seafloor is detected again. 


What is the distance between the submarine and the sea floor?

3000

m

m

0

/

1