4.6.1 Waves In Air, Fluids And Solids

Question 1

Waves are what ?

Answer 1

Either transverse or longitudinal

Question 2

Example of a transverse wave

Answer 2

The ripples on a water surface are an example of a transverse wave

Question 3

What do longitudinal waves show ?

Answer 3

They show areas of compression and rare faction

Question 4

Example of a longitudinal wave

Answer 4

Sound waves travelling through air are longitudinal

Question 5

Describe evidence that the wave itself moves?

Answer 5

For both ripples on a water surface and sound waves in air, it’s the wave and NOT the water or air itself that travels

Question 6

Describe wave motion in terms of their amplitude, wavelength, frequency and period?

Answer 6

The oscillations are either parallel in longitudinal waves or perpendicular in transverse waves

Question 7

What is the amplitude of a wave ?

Answer 7

The maximum displacement of a point on a wave away from, it’s undisturbed position

Question 8

What is the wavelength of a wave?

Answer 8

The wavelength of a wave is the distance from a point on one wave to the equivalent point on the adjacent wave

Question 9

What is the frequency of a wave?

Answer 9

The frequency of a wave is the number of waves passing a point every second

Question 10

Period equation

Answer 10

Period = 1/frequency

Question 11

Period units

Answer 11

Period, t, in seconds, s

Question 12

Frequency units

Answer 12

Frequency, f, in hertz, Hz

Question 13

What is the wave speeds

Answer 13

The wave speed is the speed at which the energy is transferred ( or the wave moves) through the medium.

Question 14

Wave equation

Answer 14

Wave speed = frequency x wavelength

Question 15

Wave speed units

Answer 15

Wave speed, v, in metres per second, m/s

Question 16

Frequency units

Answer 16

Frequency, f, in hertz, Hz

Question 17

Wavelength units

Answer 17

Wavelength, alpha, in metres, m

Question 18

How to measure distance travelled

Answer 18

Use a ruler to measure the distance and then a stop watch to measure the time.

Distance / time

Question 19

Show how changes in velocity, frequency and wavelength, in transmission of sound waves from one medium to another, are inter- related

Answer 19

the wavelength of the sound wave decreases. the frequency of the sound wave stays the same. the velocity of the sound wave decreases (since wave speed = frequency × wavelength)

Question 20

How can waves be reflected?

Answer 20

At the boundary between two different materials

Question 21

How can waves be absorbed or transmitted?

Answer 21

At the boundary between two different materials

Question 22

show a ray diagram showing refraction at the boundary between air and glass

Answer 22

Question 23

How does transmission reflection and absorption affect waves?

Answer 23

When a light wave with a single frequency strikes an object, a number of things could happen. The light wave could be absorbed by the object, in which case its energy is converted to heat. The light wave could be reflected by the object. And the light wave could be transmitted by the object.

Question 24

what do soundwaves do when travelling through solids?

Answer 24

cause vibrations in the solid

Question 25

what do soundwaves do within the ear?

Answer 25

sound waves cause the ear drum and other parts to vibrate which causes the sensation of sound. The conversion of sound waves to vibrations of solids works over a limited frequency range. This restricts the limits of human hearing.

Question 26

Describe the processes which convert wave disturbances between sound waves and vibrations in solids

Answer 26

Sound waves can travel through solids causing vibrations in the solid. Within the ear, sound waves cause the ear drum and other parts to vibrate which causes the sensation of sound. The conversion of sound waves to vibrations of solids works over a limited frequency range.

Question 27

describe the effect of sound waves on the ear drum

Answer 27

The eardrum vibrations caused by sound waves move the chain of tiny bones in the middle ear transferring the sound vibrations into the cochlea of the inner ear.

Question 28

explain why such processes only work over a limited frequency range and the relevance of this to human hearing

Answer 28

The human ear is capable of hearing sounds with frequencies between 20-20,000HZ Because sound waves are caused by vibrating particles, the denser the medium, the faster the sound travels. Meaning you can't hear sound in a vacuum are there are no particles. Sound generally travels faster in solids than liquids or gases because solids are the most dense.

Question 29

what is the range of normal human hearing?

Answer 29

20 Hz to 20 kHz

Question 30

describe how the differences in velocity, absorption and reflection between different types of wave in solids and liquids can be used both for detection and exploration of structures which are hidden from direct observation.

Answer 30

Ultrasound waves have a frequency higher than the upper limit of hearing for humans. Ultrasound waves are partially reflected when they meet a boundary between two different media. The time taken for the reflections to reach a detector can be used to determine how far away such a boundary is. This allows ultrasound waves to be used for both medical and industrial imaging. Seismic waves are produced by earthquakes. P-waves are longitudinal, seismic waves. P-waves travel at different speeds through solids and liquids. S-waves are transverse, seismic waves. S-waves cannot travel through a liquid. P-waves and S-waves provide evidence for the structure and size of the Earth’s core. Echo sounding, using high frequency sound waves is used to detect objects in deep water and measure water depth.

Question 31

what did the study of seismic waves provide?

Answer 31

new evidence that led to discoveries about parts of the Earth which are not directly observable.