Using Waves

Question 1

How do sound waves travel through a solid?

Answer 1

The particles in the solid vibrate and transfer kinetic energy through the material.

Question 2

How does the human ear work?

Answer 2

1. The outer ear collects the sound which travels into the ear
2. The sound waves cause the eardrum to vibrate at the same frequency
3. This is amplified by three ossicles (small bones)
4. This causes the hair in the cochlea to vibrate
5. The cochlea converts the vibrations into electrical signals
6. The signals are passed to brain through the auditory nerve
7. The brain converts the electrical signals into sound

Question 3

What is the frequency range of human hearing?

Answer 3

20 Hz - 20000 Hz

Question 4

What is an ultrasound wave?

Answer 4

A sound wave with a frequency greater than 20,000 Hz.

Question 5

What is sound of frequencies less than 20Hz called?

Answer 5

Infrasound

Question 6

What natural event causes seismic waves to be produced? What types are produced?

Answer 6

● Earthquakes
● They produce both P-waves and S-waves

Question 7

Are P waves transverse or longitudinal?

Answer 7

Longitudinal

Question 8

Are S waves transverse or longitudinal?

Answer 8

Transverse

Question 9

State a difference between the mediums that P-waves and S-waves can travel through.

Answer 9

● P-waves travel through both solids and liquids
● S-waves only travel through solids
(not liquids)

Question 10

What is the significance of P and S waves?

Answer 10

They provide evidence that the Earth has a liquid core; only P waves produced by an earthquake can be detected on the other side of the globe.

Question 11

What technique is used to detect objects in deep water and measure water depth?

Answer 11

● Echo sounding
● High frequency sound waves are emitted, reflected and detected
● Time difference between emission and detection, alongside wave speed, are used to calculate distances

Question 12

How does sonar work?

Answer 12

● When ultrasound waves are emitted they reflect off boundaries and their echoes are detected.
● The speed of the ultrasound is known and also the time it takes to detect the echoes.
● The equation distance=speed x time is used to find the distance travelled.
● The distance travelled is halved to give the distance between emitter and boundary (as the wave had to travel there and back

Question 13

How does foetal scanning work?

Answer 13

● An ultrasound wave is sent into the patient’s body. It passes through the body and reflects off the organs and tissue.
● The device then uses the reflected ultrasound waves to produce an image of the foetus.
● Ultrasound is safe and therefore does not damage cells.