Topic 4 - Waves

Question 1

Waves transfer ___ and ___ but do not transfer ___

Answer 1

Waves transfer Energy and information but do not transfer matter.

Question 2

What are the two types of waves?

Answer 2

Transverse

Longitudinal

Question 3

What is transverse wave?

Answer 3

A wave for which the oscillations are perpendicular to the direction of energy transfer.

Question 4

What is a longitudinal wave?

Answer 4

A wave for which the oscillations are parallel to the direction of energy transfer.

Question 5

Give two examples of transverse waves

Answer 5

1) electromagnetic waves

2) seismic s-waves

Question 6

Give two examples of longitudinal waves

Answer 6

1) sound waves

2) seismic p-waves

Question 7

What are the two parts of a longitudinal wave called?

Answer 7

Compression and rarefactions

Question 8

What are the two parts of a transverse wave called?

Answer 8

Peaks and troughs

Question 9

What is a wave’s amplitude?

Answer 9

The maximum displacement of a point on a wave from its undisturbed point

Question 10

What is wavelength?

Answer 10

The distance from a point on a wave to the same position on the adjacent wave.
Peak to peak or trough to trough

Question 11

What is the frequency of a wave

Answer 11

The number of waves that pass a given point each second.

Question 12

What is the unit used for frequency?

Answer 12

Hertz, Hz

Question 13

What is meant by a frequency of 200Hz

Answer 13

200 waves pass a given point each second.

Question 14

What is wave speed?

Answer 14

The speed at which energy is the transferred through a medium.

Question 15

What does a wave transfer?

Answer 15

Energy

Question 16

State the equation used to calculate wave speed.

Answer 16

Wave speed = frequency x wavelength

Speed(m/s) = frequency (Hz) x Wavelength (m)

Question 17

What is meant by the period of the wave? What’s the equation

Answer 17

The length of time it takes for one full wave to pass through a point.
T = 1/frequency
Second = 1/Hz

Question 18

What word is used to describe when a wave bounces off a surface?

Answer 18

Reflection

Question 19

What is the normal (in terms of reflection and refraction)?

Answer 19

A vertical imaginary line which is perpendicular to the boundary.

Question 20

What occurs when light is reflected off a boundary?

Answer 20

It bounces off a smooth flat surface so that the angle of incidence (the Angle it comes in at) is the same as the angle of reflection (the angle it leaves at).

Question 21

What is refraction?

Answer 21

Refraction is the change in speed of a wave as it reaches a boundary between two media, usually resulting in a change in direction (if it enters at an angle).

Question 22

What occurs when light is refracted at a boundary?

Answer 22

The light changes speed and direction in the new medium.
If the new medium is more dense, the light will travel slower and bend towards the normal.
If the new medium is less dense, the light will travel faster and bend away from the normal.

Question 23

When entering a denser material/medium, light waves

Answer 23

Slow down and bends towards the normal.

Question 24

When entering a less dense material, light waves

Answer 24

Speeds up and bend away from the normal

Question 25

How can refraction be measured?

Answer 25

The angle of incidence, i, and angle of of refraction, r, can be measured and compared. All angles are measured relative to the normal.

Question 26

What are the effects of absorption the of different wavelengths of waves in different mediums?

Answer 26

Some material behave differently depending on the wavelength An example is glass which will transmit visible light, but reflect UV light.

Question 27

How do sound waves travel through a solid?

Answer 27

The particles in the solid vibrate and transfer KE through the material.

Question 28

How does the human ear work?

Answer 28

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 the brain through auditory nerve 7) Brain converts the electrical signals into sound

Question 29

What is the frequency range of human hearing?

Answer 29

20Hz - 20kHz | 1kHz = 1000Hz

Question 30

What is an ultrasound wave?

Answer 30

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

Question 31

What is sound of frequencies less than 20Hz called?

Answer 31

Infrasound

Question 32

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

Answer 32

Earthquakes | They produced both P-waves and S-waves

Question 33

A P waves transverse or longitudinal?

Answer 33

Longitudinal

Question 34

Are S waves transverse or longitudinal?

Answer 34

Transverse

Question 35

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

Answer 35

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

Question 36

What is the significance of P and S waves?

Answer 36

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

Question 37

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

Answer 37

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

Question 38

How does Sonar work?

Answer 38

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 detect the echoes The equation distance = speed x time is used find the distance and travelled The distance travelled is halved to give the distance between emitter and boundary (as the wave had to travel there and back)

Question 39

How does foetal scanning work?

Answer 39

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.