Waves, light and sound Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Define a wave

A

A disturbance or oscillation that travels through space and matter accompanied by the transfer of energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is propagation of wave?

A

Direction in which waves travel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are transverse waves

A

Vibrations of the particles are perpendicular to the direction in which energy transfer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Examples of transverse waves

A

Water waves seismic waves electromagnetic waves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are longitudinal waves?

A

Vibrations of the particles are parallel to the direction in which energy transfer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Give examples of longitudinal waves

A

Sound waves and earthquake waves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do longitudinal waves have?

A

Compressions and rarefactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the wavelength?

A

Distance between two successive equivalent points.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is frequency?

A

Number of waves per unit time- Hertz Hz

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the equation for frequency?

A

F- number of waves/time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a period?

A

The time taken for one complete oscillation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the equation for a period?

A

Time/ number of waves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the amplitude?

A

The maximum displacement from the horizontal axis to the peak

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Equation for speed of sound

A

Wave speed= Frequency * Wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a ray?

A

Direction of travel- perpendicular to wave fronts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is a wave front?

A

Surface over which an optical wave has a constant phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What do circular waves have?

A

Circular wave fronts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What do plane waves have?

A

Plane wave fronts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does the pitch depend on?

A

The frequency of the source of sound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What does a high frequency produce?

A

High pitch noise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does a large amplitude produce?

A

A louder sound

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What type of wave is a light wave?

A

Transverse waves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the speed of light?

A

3 * 10^8 m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Where does light travel faster?

A

In low dense media

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What type of wave in a sound wave?

A

Longitudinal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Where does sound travel fastest?

A

In denser media

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the speed of sound in air?

A

330 m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the speed of sound in water?

A

1500 m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the speed of sound in solid?

A

5000 m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

How does light travel?

A

In straight lines

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Give the three different wave effects

A

Reflection, Diffraction and Refraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What happens to light waves when they enter a dense medium?

A

Bend towards the normal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What happens to sound waves when they enter a dense medium?

A

Bend away from the normal

34
Q

What is the range of human hearing?

A

Between 20Hz and 20 kHz

35
Q

What is an ultrasound?

A

Frequencies with above 20kHz

36
Q

What are luminous objects?

A

Emit their own light

37
Q

What are non-luminous objects?

A

They bounce off the light or they reflect the light so we can see them

38
Q

What is monochromatic light?

A

Waves that have a single frequency

39
Q

When does reflection of light happen?

A

When the light meets a boundary like a mirror, paper and surface of water

40
Q

What is the normal ray?

A

It is a virtual line that is perpendicular to the surface at the point of incidence

41
Q

What is the incident angle?

A

Angle between normal and incident ray

42
Q

What is the reflected ray?

A

Angle between the normal and reflected ray

43
Q

What are the laws of reflection?

A

Angle of incidence= Angle of reflection

Incident wave, reflected wave and the normal lie in the same plane

44
Q

What will happen to the wavelength, frequency and the speed after the reflection?

A

Nothing will change

45
Q

What is the image produced from reflection?

A

Same size, up right down, literally inverted, and virtual

46
Q

How can we distinguish an echo?

A

0.1 s

47
Q

How are good echo produced?

A
  1. The distance between the reflector and the sound source is more than 30 meters.
  2. The area of a reflector is large compared to the wavelength of the incident sound
  3. The incident sound is high pitched
48
Q

What do we use echo for?

A

To survey the depth and nature of the seabed

49
Q

What is refraction?

A

When waves enters from one medium to the other medium, it changes its direction depending upon the angle of incidence because of the change in speed

50
Q

What happens when a ray of light travels from a dense medium to a less dense medium?

A

Its speed and wavelength increases and the ray bends away

51
Q

What happens when white light enters a prism?

A

Red is deviated bent off course least by prism- violet light is deviated most

52
Q

What is the order of the colours in the spectrum?

A
Red
Orange
Yellow
Green
Blue
Indigo 
Violet
53
Q

Give the refractive index equation

A

Speed of light in air/speed of light in medium

54
Q

What is snell’s law?

A

n1 sin θ1= n2 sinθ2

55
Q

What are the conditions of total internal reflection?

A

The light must travel from denser to to less dense

Its incident angle more than critical angle

56
Q

What is the critical angle equation ?

A

Sinθ= 1/n

57
Q

What is an optical fibre?

A

A thin rod of high quality glass and very little light is absorbed by the glass

58
Q

What method does the optical fibre use?

A

Undergoes repeated total internal reflection even when the fibre is bent

59
Q

Where are optical fibres used?

A

Used in endoscopes to allow surgeons to see inside their patients and they can carry huge amounts of information as pulses of light.

60
Q

What is the focal point?

A

Where parallel light rays converge after the lens

61
Q

Describe the image formed when an object is very far way from a convex lens 3F.

A

Image is real, inverted and the image is smaller

62
Q

Describe the image formed when when an object is two focal points from a convex lens.

A

Real inverted and smaller

63
Q

Describe the image formed is between one and two focal lengths from the convex lens.

A

Real, inverted and larger

64
Q

Describe what happens when an object is one focal length from a convex lens

A

The lines do not intersect

65
Q

Describe the image formed is half focal lengths from the convex lens.

A

virtual, enlarged upright

66
Q

What is diffraction?

A

The spreading out of waves as they pass through a gap or by an obstacle

67
Q

What does a big gap in the barrier cause?

A

The disturbances are very small

68
Q

What does a small gap cause?

A

The circular disturbances are massive compared to the undisturbed wave front

69
Q

When does maximum diffraction happen?

A

When the width of the gap is equal to the wavelength of the waves

70
Q

How can sound diffract?

A

Through a doorway or around buildings

71
Q

What type of sound diffracts the best and why?

A

Low pitch- because they have a long wave length compared with the width so they spread our more

72
Q

What happens when ultrasound is diffracted?

A

There is little spreading which makes sharp focusing of ultrasound easier- good for medical scanning

73
Q

What are properties of EM waves?

A

They travel the same speed in a vacuum

74
Q

What waves are EM waves?

A

Transverse waves

75
Q

Give the order of the EM waves

A
Radio 
Microwaves
Infrared
Visible light
Ultraviolet
X-ray
Gamma Ray
76
Q

What are radio waves used for?

A

Amateur FM radio- TV broadcasts

77
Q

What are microwaves used for?

A

Mobile phones
Heating effect in microwaves
TV and communications

78
Q

What is infrared used for?

A

Radiant heaters, toasters
TV remote controllers
Security alarms
Optical fibers

79
Q

What is ultraviolet used for?

A

Sterilising equipment to kill bacteria

80
Q

Why is ultraviolet dangerous?

A

It can cause skin cancer and may damage the retina and cause blindness

81
Q

What is X-ray used for?

A

Treat cancer
Detect weapons in luggage
To take photographs that reveal flaws of metals

82
Q

What is gamma ray used for?

A

To take photographs
Killing bacteria
Treat cancer
Sterilizing food and medical equipment