Waves Flashcards

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1
Q

What do waves do

A

They travel in straight lines
Refract,reflect,diffract
Transfer energy from one place to another without the transfer of matter

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2
Q

How many pulses make up a full wave

A

2

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3
Q

What is a transverse wave

A

A transverse wave is a moving (progressive) wave that consists of oscillations occurring perpendicular (or right angled) to the direction of energy transfer.

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4
Q

What is a wavefront

A

Straight line across a wave where all particles are in phase

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5
Q

Wavelength

A

Distance between 2 corresponding points on 2 successive waves

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6
Q

Frequency

A

Number of waves complete per seconds

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7
Q

Time period

A

Time taken for one complete wave

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8
Q

Crest/peak

A

Highest part of a wave

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9
Q

Trough

A

Lowest part of a wave

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10
Q

Amplitude

A

Maximum displacement from the waves undisturbed position

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11
Q

Wave speed

A

Distance travelled by wavefront per second

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12
Q

Medium

A

Matter the wave is traveling through

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13
Q

Describe the disturbance of a transverse wave

A

The disturbance is 90 degrees to the direction of the wave

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14
Q

What is the difference between transverse and longitudinal waves

A

In a transverse wave, the disturbance is 90 degrees to the wave and they don’t require a medium to travel through
Longitudinal waves require medium and occur 180 degrees/in the same plane as the direction of the wave

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15
Q

Describe the displacement of the medium in longitudinal waves

A

Parallel to the propagation of the wave

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16
Q

What are the equivalents of peaks and troughs in longitudinal waves

A

Compressions and rarefactions

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17
Q

When do échos occur

A

when a wave is directly reflected from a boundary

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18
Q

Refraction

A

Bending of light when it passes from one medium to another of different optical densities and is caused by the changing of speed in the media

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19
Q

What happens to the wave speed, wave length, direction and frequency when a wave refracts

A

The wave speed, length and direction changes but frequency will remain the same

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20
Q

How can we minimize refraction

A

By limiting the angle at which the ray enters the new optical density

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21
Q

What is diffraction

A

The bending of waves through a gap

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22
Q

How does the size of the gap through which the wave diffracts affect the wavelength

A

The smaller the sound the larger the wavelength, the greater the wave will spread out through the gap

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23
Q

How does frequency affect the diffraction of a radio wave

A

High frequency is little diffraction
Low frequency is large diffraction

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24
Q

What are the advantages of digital signals

A

They carry

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25
Q

What is refractive index

A

The ratio of the speed of light in a vacuum to the speed of light in a medium

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26
Q

What is total internal reflection

A

Complete reflection of a light ray reaching a boundary with a less dense medium when the angle of incidence exceeds the critical angle
i>c

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27
Q

What are the uses for total internal reflection

A

Fibre optic cables-transmit light down fibres
Communication and medical examinations

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28
Q

What are the 3 parts in an optic fibre cable

A

Coating
Cladding
Core

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29
Q

What is the critical angle

A

The angle of incidence in the medium of greater optical density that results in an angle of refraction of 90 degrees

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30
Q

What are the 2 main types of lenses

A

Concave and convex
Diverging and converging

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31
Q

What happens when parallel light rays pass through a convex lense

A

They converge at one point called the principle focus.

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32
Q

What type of image will be produced when an object is closer to the lens that then focal point

A

A magnified virtual image

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33
Q

What type of image is formed when an object is further from the lens than the focal point

A

inverted and real

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34
Q

What does it mean if an image is real

A

The image can be projected on a screen

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35
Q

What is another word for backtracking lines

A

Extrapolating

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36
Q

Why does dispersion happen

A

The refractive index for frequencies of light is slightly different, causing the angle of refraction to vary by a small amount

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37
Q

What is dispersion

A

The refraction of white light as it passes and then disperses through a prism into 7 colours. The colour with the highest frequency and smallest wave length, violet refracts the most and red the least

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38
Q

Monochromatic

A

Light of a single frequency

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39
Q

Normal

A

Line that intersects given line or surface at 90 degrees

40
Q

What are the primary light colours

A

RGB

41
Q

Principal focus point

A

Point where a beam,parallel to the principal axis appears to converge after passing through the lens

42
Q

Principal axis

A

Line passing through the centre of a lens or curved/spherical mirror and parallel to the axis of symmetry

43
Q

Focal length

A

Distance between centre of a lens/curved mirror and its focal point

44
Q

Angle of refraction

A

Angle which a refracted line/ray makes with a normal line to the surface at the point of refraction

45
Q

Angle of reflection

A

Angle which a reflected line/ray makes with a normal line to the surface at the point of reflection

46
Q

Angle of incidence

A

Angle which an incident line/ray makes with a normal line to the surface at the point of reflection

47
Q

What is long sightedness called

A

Hyperopia
Close=blurry

48
Q

What is short sightedness called

A

Myopia

49
Q

Where does the image form and what lens is used to treat miopia

A

Before the retina, concave/diverging lens

50
Q

Where does the image form and what lens is used to treat hyperopia

A

Behind the retina, convex/converging lenses

51
Q

How does text appear in a mirror

A

Laterally inverted

52
Q

Describe what is meant by wave motion as illustrated by vibrations in ropes and springs, and by experiments using water waves

A

Wave motion is the transfer of energy from one point to another which can be demonstrated by hanging an object on a stretched string and sending a pulse through the string resulting in it bobbing up and down. When a pebble is dropped into a pond circular ripples move outward on the surface of the water.

53
Q

What can be modelled as a transverse wave

A

Electromagnetic radiation (such as light),
water waves
seismic S-waves

54
Q

What can be modelled as longitudinal waves

A

Sound waves
Seismic P-waves

55
Q

Reflection

A

Change in direction of a wave when it strikes a surface
i=r

56
Q

Refraction

A

Change in speed of a wave when the medium changes

57
Q

Diffraction

A

Spreading of a wave as it goes through a gap or around a corner

58
Q

Properties of the electromagnetic spectrum (3)

A

All transverse
Travel at 3x10*8 in air
Can travel through a vacuum

59
Q

Electromagnetic spectrum (7) in order of wavelength

A

Radio waves (greatest )
Microwaves
Infrared rays
Visible light (ROYGIBIV)
Ultraviolet
X-rays
Gamma rays (shortest)

60
Q

What on the electromagnetic spectrum has the highest frequency and lowest wavelength

A

Gamma rays

61
Q

Use of radio waves (3)

A

Radio and television transmissions
Astronomy
Radio frequency identification (RFID)

62
Q

Uses of microwaves (3)

A

Satellite television
Mobile phones
Microwave ovens

63
Q

Uses of infrared waves (5)

A

Thermal imaging
Optical fibres
Intruder alarms
Short range communications (remote for TV)
Electric grills

64
Q

Uses of visible light waves (3)

A

Vision
Photography
Illumination

65
Q

Uses of ultraviolet waves (3)

A

Sterilizing water
Detecting fake bank notes
Security marking

66
Q

Uses of X-ray waves (2)

A

Medical scanning (broken bones)
Security cameras (detecting metallic objects in luggage)

67
Q

Uses of gamma rays (2)

A

Sterilising food + medical equipment
Detecting + treating cancer

68
Q

Dangers of microwaves

A

Internal heating of body-cells

69
Q

Dangers of infrared waves

A

Can cause skin damage and burns

70
Q

Dangers of ultraviolet waves

A

Can cause damage to surface skin cells and eyes if exposed too long leading to cancer and eye conditions

71
Q

Dangers of X-ray and gamma rays

A

Causes mutation/damage cells in the body leading to cancer (they are ionising)

72
Q

Why/how Communication with artificial satellites uses electromagnetic waves

A

Done with microwaves
Some satellite phones use low orbit artificial satellites
Some satellite phones and direct broadcast satellite television use geostationary satellites

73
Q

Systems of communication that rely on electromagnetic waves (4)

A

Mobile phones
Bluetooth
Optical fibres
Communication with artificial satellites

74
Q

Application of electromagnetic waves in mobile phones

A

Wireless internet uses microwaves because they can penetrate some walls + only require a short aerial for transmission + reception

75
Q

Application of electromagnetic waves in Bluetooth

A

Radio waves as they pass through walls

76
Q

Application of electromagnetic waves in optical fibres

A

Visible light/infrared is used for cable television + high speed broadband connections because glass is transparent to visible light and some infrared and visible light and short wavelength infrared can carry high rates of data

77
Q

Speed of sound in air

A

330-350 m/s

78
Q

Range of frequencies audible to humans

A

20 - 20 000 Hz

79
Q

Ultrasound

A

Sound with a frequency higher than 20 000 Hz

80
Q

Types of signals that can transmit sound

A

Analogue
Digital

81
Q

Advantages of digital over analogue signals

A

Increased rate of transmission
Increased range of transmission (easier to regenerate)

82
Q

Analogue signals

A

Continuous in value

83
Q

Digital signals

A

Discrete (fixed) in values

84
Q

Describe the production of sound by vibrating
sources

A

When an object vibrates, it causes movement in surrounding air molecules. These molecules bump into the molecules close to them, causing them to vibrate as well.

85
Q

Describe the longitudinal nature of sound waves

A

all the particles of the medium (such as gas, liquid or solid) vibrate in the same direction as the wave

86
Q

Behaviour of waves (3)

A

reflection at a plane surface
refraction due to a change of speed
diffraction through a narrow gap

87
Q

Describe the formation of an optical image by a plane mirror (3)

A

Virtual
Upright
Same distance from mirror

88
Q

What are ripple tanks often used to show (4)

A

Reflection at a plane surface
Refraction due to a change in speed caused by a change in depth
Diffraction due to a gap
Diffraction due to an edge

89
Q

Principal focus/focal point

A

the point where rays of light travelling parallel to the principal axis intersect the principal axis and converge

90
Q

Use of a single lens

A

Magnifying glass when the object is just beyond the principal focus of the lens

91
Q

Uses of total internal reflection (2)

A

Optical fibres (communications, endoscopes, decorative lamps)
Prisms ( binoculars, telescopes, cameras, periscopes)

92
Q

Describe the use of converging and diverging
lenses to correct long-sightedness and short-
sightedness

A

Nearsightedness, is corrected with a diverging lens. (Forms before retina)
Farsightedness, is corrected with a converging lens (forms behind retina)

93
Q

Describe the dispersion of light as illustrated by the refraction of white light by a glass prism

A

It splits into it ROYGBIV colours

94
Q

Uses of ultrasound in non-destructive testing of materials (2)

A

medical scanning of soft tissue
sonar (including calculation of depth or distance from time and wave speed)

95
Q

How to correct long sightedness

A

Convex lens, so that the light rays are converged and can meet at the retina

96
Q

How to correct short-sightedness

A

Concave lens, so that the light rays are diverged and can meet at the retina