4) Waves Flashcards

1
Q

What do transverse waves cause particles in the medium to do?

A

Vibrate at right angles to the direction of the wave’s motion

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2
Q

What are real world examples of transverse waves?

A

Corks bobbing

Mexican wave

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3
Q

What do waves transfer?

A

Energy

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4
Q

What do longitudinal waves cause particles in the medium to do?

A

Vibrate in the same direction as the wave’s motion

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5
Q

What are examples of longitudinal waves?

A

P-waves

Sound waves

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6
Q

What do all waves have?

A

A frequency

A period of oscillation

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7
Q

What is a wave’s frequency?

A

Number of oscillations per second

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8
Q

What is an oscillation?

A

A vibration

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9
Q

What is frequency measured in?

A

Hertz (Hz)

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10
Q

What are the equations for frequency?

A
frequency = number of oscillations / time
frequency = 1 / period
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11
Q

What is a period of a wave?

A

The time taken to complete one oscillation

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12
Q

What is equation for a wave’s period?

A

period = 1 / frequency

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13
Q

What is the period of a wave measured in?

A

Seconds (s)

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14
Q

What is the amplitude of wave?

A

The greatest distance a point on a wave moves from its rest position

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15
Q

What is the wavelength?

A

The distance between two peaks of adjacent waves

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16
Q

What are wavefronts?

A

Parallel lines at the peaks of ripples

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17
Q

What is the equation for wave speed?

A

wave speed = frequency x wavelength

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18
Q

What is the best way to observe water waves?

A

A ripple tank

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19
Q

What happens when a wave travels from one medium to another?

A

Speed changes
Wavelength changes
Frequency stays the same

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20
Q

What part of waves are directly proportional?

A

Speed and wavelength

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21
Q

Why is the frequency of a wave unchanged between mediums?

A

The source is still producing the same number of osciallations per seconds

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22
Q

When does reflection happen?

A

Wave hits a flat surface (plane) and bounces off

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23
Q

What can happen to waves at the boudnary of a medium?

A

Refraction
Reflection
Absorbtion
Transmission

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24
Q

Why does refraction happen?

A

If the wave crosses the medium at an angle the change in speed will cause the direction to change

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25
Q

What is absorbtion?

A

When energy is absorbed by the material

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26
Q

What is transmission?

A

When waves catry on travelling through a new material

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27
Q

What does transmission often lead to?

A

Refraction

28
Q

What is the angle of incidence?

A

The angle between the incident ray and the normal

29
Q

What is the incident ray?

A

The incoming light ray to a medium

30
Q

What is the normal line?

A

A line at 90 degrees to the plane

31
Q

What is the angle of reflection?

A

The angle between the reflected ray and the normal

32
Q

What does the law of reflection state?

A

The angle of incidence = the angle of reflection

33
Q

What is the flat surface light rays hit called?

A

The plane

34
Q

What happens to light when it enters a more optically dense medium?

A

It slows down

35
Q

What happens to light when it enters a less optically dense medium?

A

It speeds up

36
Q

How does light refract when entering a more optically dense medium?

A

It is refracted closer to the normal

Angle of refraction is smaller than angle of incidence

37
Q

How does light refract when entering a less optically dense medium?

A

It is refracted further from the normal

Angle of refraction is larger than angle of incidence

38
Q

What type of waves are sound?

A

Longitudinal waves

39
Q

How is sound produced?

A

By the vibration of particles in a medium

40
Q

What is a medium?

A

The subtance that waves travel through

41
Q

What do waves travel in a series of?

A

Compressions and rarefractions

42
Q

What are sound compressions?

A

Where the medium is squashed together?

43
Q

What are sound rarefractions?

A

Where the medium is stretched apart

44
Q

What sound range can we hear?

A

20Hz - 20,000 Hz

45
Q

What is ultrasound?

A

Sound waves above 20,000 Hz

46
Q

What is infrasound?

A

Sound waves below 20 Hz

47
Q

What are seismic waves?

A

Infrasound

48
Q

What do doctors use ultrasound for?

A

Scanning a developing foetus

49
Q

How does a rigid medium affect the speed of sound?

A

More rigid = higher speed

50
Q

How does a compressible medium affect the speed of sound?

A

More compressible = lower speed

51
Q

How quick is sound in gases?

A

Very slow as gas is easily compressable

52
Q

How quick is sound in solids?

A

Quicker than liquids or gases as more rigid

53
Q

How quick is sound in gases?

A

Quicker than gas as more rigid

54
Q

Why can sound waves not travel in space?

A

It is a vacuum
No medium for sound waves to travel through
No particles to vibrate

55
Q

What are the stages of sound in the ear?

A

1) Sound waves make ear drum vibrate
2) Passed via small bones (anvil, hammer, stirrup)
3) Auditory nerve
4) Sends an electrical signal to brain

56
Q

What can we use ultrasound waves for?

A

Medical imaging

Industrial imaging

57
Q

How is ultrasound used in medicine?

A

1) Ultrasound waves pass through body
2) When reaching a boundary between two different materials, some will be reflected which we can detect
3) A computer processes the timing and distribution of these waves and develops a video image

58
Q

How is ultrasound used in industry?

A

Can find flaws in materials
Usuallly ultrasound is reflcted by the far side of a material
Flaws reflect waves sooner telling us there is a problem

59
Q

How is ultrasound useds to find water depth?

A

Echo sounding

1) Send ultrasound pulse into water
2) When pulse hits surface it is reflected back
3) We can work out distance travelled by recording time taken

60
Q

What 2 types of seismic wave do earthquakes produce?

A

P-waves (primary)

S-waves (secondary)

61
Q

What type of wave are P-waves?

A

Longitudinal seismic waves

62
Q

What type of wave are S-waves?

A

Transverse, seismic waves

63
Q

What can S-waves travel through?

A

Solids

64
Q

What can P-waves travel through?

A

Solids

Liquids

65
Q

What happens if the incident ray is at the critical angle?

A

The refracted light travels parallel to the boundary of two mediums