SP3e Ultrasound and infrasound

Question 1

What is ultrasound?

Answer 1

a sound with a higher frequency than humans can hear – above 20 000 Hz.

Question 2

What do animals such as bats and dolphins use ultrasound for?

Answer 2

to detect objects - echolocation.

Question 3

How can ultrasound be used to find faults in manufactured items?

Answer 3

The machine is passed over the object being tested. If there are no cracks, it will detect just one echo from the far side of the object.​
If there is a crack it will detect an echo from the crack as well. The timing of this echo can be used to work out how deep into the material the crack is located.

Question 4

How do ships and submarines use ultrasound? (SONAR)

Answer 4

A pulse of ultrasound is emitted, and some is reflected off the bottom. A microphone detects the echo, and the distance travelled can be calculated using: distance = speed x time

Question 5

What is infrasound?

Answer 5

a sound with a lower frequency than humans can hear - below 20 Hz. Animals use it to communicate.

Question 6

What is one thing infrasound is produced by?

Answer 6

volcanoes and earthquakes. Some people believe that animals can sense the infrasound before the eruptions or earthquakes start.

Question 7

P-waves? (2)

Answer 7

.longitudinal waves, and so are infrasound waves​
.can travel through solids and liquids

Question 8

S-waves? (2)

Answer 8

.transverse waves, and so are not infrasound waves​
.can travel through solids but not liquids

Question 9

What are sesmic waves?

Answer 9

waves produced by an explosion or earthquake and that travel through the Earth. They include P-waves and S-waves.

Question 10

What is the S-wave shadow zone?

Answer 10

zone where S-waves from an earthquake do not reach a part of the Earth.

Question 11

What is the P-wave shadow zone?

Answer 11

a band around the Earth opposite the earthquake. The zone still has weak waves arriving that have been refelcted by an inner core that is solid.