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Waves Flashcards

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1
Q

eg transverse waves

A

ripples on surface of water

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2
Q

eg longitudinal waves

A

sound waves travelling in air

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3
Q

what do waves do

A

transfer energy from one place to another

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4
Q

what type of energy do the ripples on water transfer

A

kinetic energy

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5
Q

what are the up and down movements of waves called

A

ocsillations

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6
Q

describe transverse wave

A

ocsillations are perpendicular to direction of energy transfer

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7
Q

what does ‘perpendicular’ mean

A

at right angles

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8
Q

how do sound waves travel

A

as particles in the air move from side to side

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9
Q

what are ‘compressions ‘ in air

A

regions where the air particles are very close tgether

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10
Q

what comes between compressions

A

rarefactions

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11
Q

what are rarefactions

A

regions where air is spaced out

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12
Q

describe longitudinal wave

A

oscillations parallel to direction of energy transfer

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13
Q

what do all longitudinal waves require to travel in

A

a medium, eg
air
liquid
solid

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14
Q

what is different between transverse and longitudinal in terms of needing a medium in order to travel

A

NOT ALL transverse need a medium to travel in
ALL longitudinal waves need a medium

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15
Q

what is travelling in terms of ripples on a water surface

A

the wave is travelling, not the water

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16
Q

what is travelling in terms of sound waves in air

A

the wave is travelling, not the air

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17
Q

what can a slinky be used to represent

A

transverse waves
(eg ripples on surface of water)

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18
Q

what does the red dot in the slinky represent

A

-a single point (eg a water molecule)

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19
Q

how does the slinky example prove that the wave and not
the water / air itself travels.

A

when wave travels through/ slinky is moved,
the dot oscillates up and down
but doesn’t travel along the medium

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20
Q

what happens when longitudinal waves are sent along slinky

A

red dot oscillates from side to side
doesn’t travel through medium

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21
Q

what does red dot in slinky, in transverse wave represent

A

particle of air

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22
Q

what is amplitude- define it

A

the maximum displacement of a point
on a wave away from its undisturbed position.

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23
Q

where is the undisturbed position

A

the points horizontally along the centre where the wave isn’t moving

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24
Q

define wavelength

A

distance from a point on one wave
to the equivalent point on the adjacent wave

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25
Q

where can a wavelength be on a longitudinal wave

A

at any point,
eg middle or bottom
(just needs to be the equivalent point on the next wave)

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26
Q

symbol for wavelength

A

greek letter lamda
λ

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27
Q

how to measure wavelength on longitudinal wave

A

from one compression to next compression
from one rarefaction to next rarefaction

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28
Q

define frequency

A

number of waves passing point each second

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29
Q

unit for frequency

A

Hz

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30
Q

one Hz is equal to……

A

one wave per second

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31
Q

what does period of a wave mean

A

time in seconds for one wave to pass a point

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32
Q

unit for period

A

seconds

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33
Q

define wave speed

A

speed at which wave moves through the medium

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34
Q

equation for wavespeed is:
v = f λ
what do the symbols represent

A

wavespeed= frequency x wavelength

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35
Q

what is wavespeed (v) measured in

A

m/s

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36
Q

what is frequency (f) measured in

A

Hz

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37
Q

what is wavelength λ measured in

A

m

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38
Q

describe a method to measure the speed of sound waves in
air
5 points

A

-2 people stand 500 m apart
-person A has symbols
person B has timer
-B starts timing when she sees A clash cymbals together
-B stops timing when she hears sound of cymbals clashing
-Do equation-
speed of sound waves=
Distance travelled / time taken

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39
Q

the 2 problems with method of measuring speed of sound waves
- describe what you mean

A
  • everyone has different reaction time

takes fraction of a second between
seeing cymbals & starting timer and also between hearing sound and stopping timer

  • time btwn seeing cymbals clash and hearing them is short

means its difficult to press timer at correct time

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40
Q

how to reduce error of different reaction times

A

-large number of observers
use all results, discard anomalous results, find mean

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41
Q

how to reduce problem of short time between hearing + seeing

A

increase distance between person A and B

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42
Q

what is a ripple tank used for

A

to observe the features of water waves

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43
Q

describe what a ripple tank looks like

A

shallow tray of water
a vibrating bar in the water
bar is connected to power pack

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44
Q

what happens when the bar vibrates in the water

A

it creates waves across the surface of the water

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45
Q

what is above and what is below the ripple tank

A

above is a lamp
below is sheet of WHITE paper

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46
Q

what happens when light shines through the water

A

it creates an image of the waves on the paper

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47
Q

what are we using the ripple tank to measure x3

A

wavelength
frequency
speed
of waves

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48
Q

how are we going to video the waves shown on the paper and why in this way

A

using a mobile phone
we can freeze the video
play video at different speeds

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49
Q

how do you measure wavelength from the waves reflected on the paper
5 points

A

put the ruler next to paper
freeze image of waves
measure distance of 10 wavelengths
divide by 10 for 1 wavelength
turn from cm into metres

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50
Q

how do you measure frequency of the waves reflected on the paper

A

put timer next to paper
play video in slow motion
count number of waves passing a point in 10 seconds
divide answer by 10 to get frequency

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51
Q

2 ways to work out speed of the waves reflected on the paper

A

-use equation: v = f λ
(do frequency x wavelength)
OR
-choose a wave
-measure the time it takes to move the length of tank
- then do: speed = distance/time

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52
Q

one issue that arises as there are 2 ways to work out speed of the waves reflected on the paper

why this issue arises

A

-may get slightly different results
-due to measurement errors eg timing

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53
Q

list all the components / parts of the set up to measure frequency/wavelength/speed of waves in a solid in order

A

signal generator
vibration generator
string
wooden bridge
pulley on a clamp
mass

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54
Q

describe the apparatus used to measure frequency/ wavelength / speed of waves in a solid

A

-string with one end attached to vibration generator
-hanging mass at other end of string
-vibrator generator attached to signal generator

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55
Q

what does the mass at the end of the string do

A

keeps string taut

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56
Q

what does the signal generator let us do

A

change the frequency of vibration of the string

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57
Q

what happens when we turn on the power in the apparatus used to asses waves in a solid

A

the string vibrates

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58
Q

when, where, why do we get a standing wave

A

in the string
at certain frequencies
due to resonance

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59
Q

give an everyday example of resonance

A

stringed musical instruments eg guitar.

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60
Q

what do we use to measure the wavelength of the standing wave

A

a ruler

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61
Q

how do we measure the wavelength ( from where to where ) in the RP for assessing waves in a solid

A

measure length of standing wave from wooden bridge to vibration generator
turn from cm to m

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62
Q

how do we find out frequency for waves in a solid

A

read the frequency generator

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63
Q

how do we calculate speed of waves in a solid

A

calculate speed of wave by: v = f λ

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64
Q

what happens if we increase the frequency through a standing wave

A

wavelength increases

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65
Q

how would you calculate the wavelength of a wave with 3 half wavelengths in the RP for waves through a solid

A

measure distance from wooden bridge to vibration generator
(eg 0.125 metres)
divide this length by number of half wavelengths
(eg. 0.125m / 3)
then times answer by 2
(eg… ( 0.125m/3) x 2) =0.143m

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66
Q

In the RP for waves in a solid, what does the wave speed of the string depend on

A

tautness of string
&
mass/cm

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67
Q

when wave hits boundary with different material, 3 things can happen….

A

waves are either:
transmitted
absorbed
reflected

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68
Q

describe what it means when a wave is transmitted

A

passing through the material doesn’t change the wave

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69
Q

what could potentially happen when a wave is transmitted

A

-refraction
(waves can change direction)

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70
Q

what happens when a wave is absorbed

A

energy of wave absorbed
wave wont pass through material

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71
Q

what is meant when wave is reflected

A

wave reflected off materials surface

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72
Q

whether transmittion, reflection, absorbtion happens depends on….

A

on the material
on the wavelength

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73
Q

describe initial parts of ray diagram for reflection

A

mirror line- horizontal/ vertical line, dashed along one side

incident ray- angled straight line, touches bottom of mirror line

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74
Q

what parts do you add on to your ray diagram for reflection

A

normal- draw dotted line at right angles to surface of mirror

angle of incidence- measure angle between incident ray and normal

angle of reflection- measure same angle ( of incidence) on other side of the normal

reflected ray- angled straight line going downwards from normal, with same angle as angle of incidence

( basically your angle and ray of incidence is reflected on the other side by the normal)

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75
Q

key fact for reflection in all waves

A

angle of reflection= angle of incidence

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76
Q

how to use a ray diagram to workout where an image will appear in the mirror if an object is infront of a mirror

A

-draw incident ray from object to mirror
-draw normal at right angles to mirror’s surface
-draw reflected ray
-draw #2 normal higher up , #2 incident ray from object to mirror #2 reflected ray
-extend both reflected rays so they meet at a point
-that point= position of image

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77
Q

what must you remember when drawing rays

A

the arrows showing direction

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78
Q

what things used to investigate reflection and refraction

A

ray box
lens
slit

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79
Q

what do the ray box, lens and slit produce when used together

A

narrow ray of light

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80
Q

hazard of ray box, and a control for this

A

ray boxes get hot
switch off when not in use

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81
Q

what alternative can be used to a ray box, why don’t we use this instead

A

a laser, dangerous

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82
Q

RP 9
Part 1
how to make reflected ray and refracted ray- up till transmitted ray

A

-on A3 paper draw straight line down center
use ruler
- Normal- ( line at right angle )
use protractor- label N
-place glass block against first line so normal goes through center
-draw around glass block
-turn off all lights
-incident ray- use ray block so ray hits block at normal
-adjust ray box - change angle of incidence till reflected ray & transmitted ray visible

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83
Q

how do we draw the normal in when making rays of reflection and refraction

A

use protractor to draw line at right angles to initial line

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84
Q

what do we label the normal when making rays of reflection and refraction

A

N

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85
Q

how do we make the incident ray when making rays of reflection and refraction

A

use ray block so ray hits block at normal

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86
Q

when do we stop adjusting the ray block

A

when reflected ray and transmitted ray are visible

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87
Q

what is the transmitted ray

A

ray leaving block from opposite side

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88
Q

RP 9
part 2
what do we do once we have the transmitted ray and the ray of reflection when making rays of reflection and refraction
( up to line through glass block)

A

-use crosses to mark path of all three rays
( transmitted, reflected, incidence)
-turn on lights
-switch off ray box
- remove glass block
-draw all rays ( use the crosses )
- draw line to show path of transmitted ray through glass block

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89
Q

how many x’s do we put on each ray when making rays of reflection and refraction

A

1 on reflected
1 on incident
2 on transmitted

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90
Q

RP 9
part 3
what do we do once we’ve drawn the line showing the path of transmitted ray through the glass block- when making rays of reflection and refraction

A

use protractor to measure important angles
do whole experiment again- use different material

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91
Q

RP 9 - making rays of reflection and refraction
what are the important angles to measure

A

reflection
incidence
refraction

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92
Q

where is the angle of refraction

A

angle between normal and the path of the transmitted ray through the block

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93
Q

what other material can u use when repeating RP 9
( making rays of reflection and refraction)

A

perspex (plastic)

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94
Q

what will you find when you repeat RP 9 with different material + what materials

A

angle of incidence and reflection are the same in glass and Perspex

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95
Q

why does angle of incidence and reflection stay same in glass and Perspex in RP 9

A

angles of incidence and reflection X depend on material

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96
Q

what angle will change when repeating RP 9 with Perspex instead of glass + why

A

angle of refraction ,
as angle of refractions different for different materials

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97
Q

is sound longitudinal or transverse wave

A

longitudinal

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98
Q

what happens when sound waves move through air

A

air particles vibrate from side to side

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99
Q

can air particles vibrations move from one medium to another

A

yes

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100
Q

when ….. waves move through air, air particles vibrate from ….. to ….. these vibrations can move from one ……… to ……..
eg from …. to ….

A

when sound waves move through air, air particles vibrate from side to side. these vibrations can move from one medium to another
eg from air to solid.

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101
Q

what is one key part of a microphone

A

paper cone

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102
Q

what happens when sound waves hit the cone in a microphone

A

cone vibrates

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103
Q

when the paper cone vibrates, what does the microphone do

A

microphone converts vibrations into electric signals

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104
Q

describe movement of sound waves into ear

A

sound waves funneled into ear where they hit eardrum

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105
Q

what is the ear drum

A

thin membrane

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106
Q

what do the sound waves in the ear cause

A

cause ear drum &
other parts of inner ear
vibrate
causing sound

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107
Q

sound waves in air trigger

A

vibrations in solids

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108
Q

vibrations in solids can only be triggered by sound waves at…..

A

limited range of frequencies

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109
Q

what is range of normal human hearing

A

20-20,000 Hz

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110
Q

what is 20,000 Hz in kHz

A

20,000 Hz = 20 KHz

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111
Q

what potentially happens if frequency of sound wave is outside of 20Hz-20,000Hz

A

eardrum not vibrate

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112
Q

what can happen when wave moves from 1 medium to another

A

speed can change

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113
Q

give example of a wave slower in 1 medium compared to another

A

sound waves-
travel faster in solids than in gases

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114
Q

why do sound waves travel faster in solids than gas

A

particles closer together in solid
vibrations pass more easily (from particle to particle)

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115
Q

what is changed when wavespeed changes

A

wavelength

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116
Q

when wavespeed increases, what happens to wavelength

A

increases

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117
Q

when a wave changes medium, the frequency

A

does not change

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118
Q

why does frequency not change when wave changes medium

A

waves would have to be created and destroyed at the boundary, thats’ not possible

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119
Q

how can we view features of sound waves

A

connect microphone to cathode ray oscilloscope

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120
Q

what is issue with cathode ray oscilloscope

A

represents sound waves as transverse
(sound waves are longitudinal)

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121
Q

if a sound has high frequency, it has a

A

high pitch

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122
Q

how to know if a sound has low pitch

A

if it has low frequency

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123
Q

if a sound has a small amplitude, it has a

A

quiet sound

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124
Q

how to know if a sound is loud from looking at cathode ray oscilloscope

A

if it has large amplitude

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125
Q

high frequency sound wave means

A

high pitch

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126
Q

large amplitude sound wave means

A

loud sound

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127
Q

low frequency soundwave means

A

low pitch

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128
Q

small amplitude sound wave means

A

quiet sound

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129
Q

if a sound is high pitched, it will have a

A

high frequency

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130
Q

if a sound is loud it will have a

A

large amplitude

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131
Q

if a sound is low pitched it will have a

A

low frequency

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132
Q

if a sound is quiet it will have a

A

small amplitude

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133
Q

sound waves can only move through a …….. for example through …….

A

medium
eg- solid

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134
Q

why can sound waves only move through a medium

A

because sound waves move by particles vibrating

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135
Q

where can sound waves not pass through, why

A

cant pass through vacuum
no particles

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136
Q

can sound waves be reflected

A

yas

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137
Q

what is a reflected sound wave called

A

echo

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138
Q

what are ultrasound waves

A

waves with frequency higher than upper limit of human hearing

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139
Q

what is upper limit of human hearing

A

20,000Hz

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140
Q

what happens to ultrasound waves at the boundary between 2 different densities

A

ultrasound waves partially reflect

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141
Q

a device that gives out + detects ultrasound waves

A

ultrasound probe

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142
Q

if we know the time taken for ultrasound pulse to leave probe, bounce off kidney and then be detected by probe, we can calculate……

A

distance between probe and kidney

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143
Q

the distance between the detector and the boundary can be calculated if you know

A

time taken for ultrasound reflections to be detected by the detector

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144
Q

ultrasounds can be used to for……

A

producing images of internal organ
producing images of foetus
industrial imaging

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145
Q

what must an organ have/ not have to be able to produce an image of it using ultrasound

A

organ must not be surrounded by bone

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146
Q

what is safer:
ultrasound or x-ray

A

ultrasound

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147
Q

why is ultrasound safer than x-ray
2 points

A

doesnt cause mutations
doesnt increase cancer risk

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148
Q

example of ultrasound being used for industrial imaging

A

ultrasound used to scan a pipe

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149
Q

why would ultrasound be used to scan a pipe
2 reasons

A

-detect hidden defects
-problems with a weld

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150
Q

how can we use ultrasound to work out distance

A

use equation:
(distance = speed x time)

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151
Q

what is distance measured in

A

metres

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152
Q

what is speed measured in

A

m/s

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153
Q

what is time measured in

A

seconds

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154
Q

ship uses ultrasound to measure distance to seabed.
ultrasound pulse is emitted
it takes 1.2 seconds for reflected pulse to return to ship
calculate depth of sea bed
speed of ultrasound in water is 1600 m/s

A

s=vxt
s= 1600 x 1.2
distance = 1920 meters
1920/2 =960 metres

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155
Q

why sometimes divide by 2 when working out distance using ultrasound wave

A

because your answer could be from ship to seabed and then seabed back to ship

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156
Q

what is outer layer of earth made of- describe it

A

solid crust- very thin

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157
Q

what comes under crust

A

mantle

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158
Q

what is max depth of the solid outer crust

A

50 km+

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159
Q

is mantle considered solid, liquid , gas

A

solid

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160
Q

what parts of mantle can flow very slowly

A

parts of upper mantle

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161
Q

what comes under mantle

A

outer core

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162
Q

is outer core solid, liquid. gas

A

liquid

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163
Q

what comes under outer core

A

inner core

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164
Q

is inner core solid, liquid,gas

A

solid

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165
Q

there is ….. way for scientists to directly ….. the ……. of earth

A

there is no way for scientists to directly observe the interior of the earth

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166
Q

deepest mines go ……… into the crust

A

a few km

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167
Q

how do scientist know the internal structure of earth

A

due to earth quakes

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168
Q

why do earthquakes happen

A

sudden movement between tectonic plates and earths crust

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169
Q

the sudden movement between tectonic plates causes….

A

seismic waves

170
Q

what do seismic waves do

A

carry energy away from the earthquake and pass through the earth

171
Q

how are seismic waves detected

A

by seismometers in different countries

172
Q

info about the interior of the earth comes from…..

A

the pattern of waves on the seismometer

173
Q

2 main types of seismic waves

A

p waves
s waves

174
Q

e p waves or s waves longitudinal

A

p waves

174
Q

e p waves or s waves longitudinal

A

p waves

174
Q

e p waves or s waves longitudinal

A

p waves

174
Q

e p waves or s waves longitudinal

A

p waves

174
Q

are p waves or s waves longitudinal
choose one.

A

p waves

175
Q

p waves can pass through

A

solids and liquids

176
Q

which travel faster, p or s waves

A

p waves

177
Q

are s waves longitudinal or transverse

A

transverse

178
Q

s waves pass through

A

solids only

179
Q

describe pathway of s waves through the earth

A

curved paths
(start at point,
curve outwards,
go through crust and mantle)

180
Q

why do seismic (s) waves travel in curved paths

A

due to density changes in the earth

181
Q

what do you call the part of the earth where no s waves can be detected

A

s wave shadow zone

182
Q

why is the s wave shadow zone created

A

because s waves can’t pass through liquid
(the waves turning point is when it reaches liquid )

183
Q

s waves cant travel through liquids, this causes the s wave shadow zone. Scientists used this info to work out that…..

A

the earth must contain a liquid core

184
Q

where can p waves be detected on the earths surface

A

https://images.app.goo.gl/cpvbFLuUXMB7qTsYA
p waves can be detected around most of the earth
except 2 parts opposite each other on north and south of earth

185
Q

what do we call the places where p waves cannot be detected

A

p wave shadow zones

186
Q

what is the reason for p wave shadow zones

A

p waves travel faster in solids than liquid

187
Q

what happens when p waves enter liquid outer core

A

p waves slow down
causing refraction ( change in direction)

188
Q

2 times p waves refract in the earths interior

A

when they leave the outer core
when they enter the outer core

189
Q

p waves refract when entering and leaving the outer core. What does this confirm

A

that the outer core is a liquid
p waves move slower through liquid, that why they refract in outer core

190
Q

what can be detected in the p wave shadow zone

A

faint p waves

191
Q

faint p waves can be detected in the p wave shadow zone. this is used by scientists to prove that…..

A

the earth contains a solid inner core

192
Q

scientists have measured the ………waves of ……… of ………..

A

scientists have measured the seismic waves of thousands of earthquakes

193
Q

scientists have measured the seismic waves of thousands of earthquakes. They’ve used these to work out

A

thickness of crust, mantle, outer, inner cores

194
Q

light is an example of an ……………. wave

A

electromagnetic

195
Q

are electromagnetic waves longitudinal or transverse

A

transverse

196
Q

what do electromagnetic waves do

A

transfer energy from source of wave to absorber

197
Q

what do electromagnetic waves in a microwave oven do - give examples

A

transfer energy from the source- the oven
to the absorber-
the food

198
Q

what is the electromagnetic wave in the microwave oven

A

microwave

199
Q

what is the electromagnetic wave in solar panels

A

light waves

200
Q

what do electromagnetic waves in a solar panel do

A

transfer energy from the source-
the sun
to the absorber-
solar panels

201
Q

what happens to white light passed through a prism

A

it splits into a spectrum

202
Q

what type of light splits into a spectrum when passed through a prism

A

white light

203
Q

each colour of light has a different..,….. and ………

A

wavelength and frequency

204
Q

order of colour spectrum

A

red
orange
yellow
green
blue
indigo
violet

Roy. G. Biv

205
Q

describe wavelength of waves on red end of spectrum

A

longer wavelength

206
Q

describe frequency of waves on red end of spectrum

A

lower frequency

207
Q

describe wavelength of waves on violet end of spectrum

A

shorter wavelength

208
Q

describe frequency of waves on violet end of spectrum

A

higher frequency

209
Q

visible light forms a …… part of the electromagnetic spectrum

A

small part

210
Q

visible light is the only part of the spectrum that

A

can be detected by the human eye

211
Q

state the electromagnetic spectrum from low frequency to high frequency

A

radio
microwaves
infrared
visible light
ultra violet
x rays
gamma rays

212
Q

what is the mnemonic to remember electromagnetic spectrum

A

raging
Martians
invaded
venus
using
X-ray
guns

213
Q

what happens to frequency from radio to gamma rays

A

frequency increases from radio to gamma rays

214
Q

what happens to wavelength from radio to gamma rays

A

wavelength decreases from radio to gamma rays

215
Q

scientists say the electromagnetic spectrum is a ……

A

continuous spectrum

216
Q

what does a continuous spectrum mean

A

the cut off point between one type of wave and another is not always clear

217
Q

do electromagnetic waves need a a medium to travel in ?

A

no

218
Q

true or false:
electromagnetic waves CAN NOT travel through a vacuum

A

false,
electromagnetic waves CAN travel through a vacuum

219
Q

what can you say about the speed of electromagnetic waves in a vacuum

A

all electromagnetic waves travel at the SAME speed in a vacuum

220
Q

what is the speed of all electromagnetic waves in a vacuum-

A

300,000 000 m/s

221
Q

…,….. materials absorb, ………. or reflect ………… waves

A

different materials absorb, transmit or reflect electromagnetic waves.

222
Q

whether an electromagnetic wave is absorbed, transmitted or reflected depends on ……..

A

the wavelength

223
Q

describe how different materials act differently to the same wave in a microwave oven

A

microwaves are absorbed by food- which contain water particles
microwaves are reflected from metals

224
Q

describe how different surfaces act differently to light waves

A

light rays absorbed by black surfaces
light rays reflected from shiny , metallic surfaces

225
Q

what happens to light as it passes through water

A

light appears to change direction as it passes through water

226
Q

light appears to change direction as it passes through water. This is due to …….

A

refraction

227
Q

when waves change speed, they can also change……

A

direction

228
Q

when does the speed of a wave change

A

when it moves from one medium to another

229
Q

what is used to illustrate how waves change direction when changing speed (moving from one medium to another)

A

a ray diagram

230
Q

what happens to light when it passes from air into glass and what does this in turn cause

A

velocity of light decreases. This causes the direction of wave to change

231
Q

what does ray diagram of light ray from air to glass look like

A

normal at right angle to surface of glass
ray bends towards normal
light ray passes through glass block
when ray passes from glass back to air,
ray bends away from normal
this causes image of object to appear to have shifted position

232
Q

what happens to light ray as it passes from glass back to air

A

velocity increases, bends away from normal

233
Q

why does light ray bend towards normal

A

because velocity decreases

234
Q

in a ray diagram…..
there is a normal at a right angle to surface of glass
ray bends towards normal as it slows down
light ray passes through glass block
when ray passes from glass back to air,
ray bends away from normal because it speeds up
what does this cause?

A

causes image of object to appear to have shifted position

235
Q

what is the light ray that enters the glass block called

A

incident ray

236
Q

what is the light ray that leaves the glass block called

A

refracted ray

237
Q

when can refraction happen
2 points

A

when any wave changes speed
going from one medium to another

238
Q

what is the one exception when waves enter/ leave a different medium but don’t change direction - refraction doesnt happen

A

when they enter/ leave at right angles to the surface, along the normal

239
Q

what diagrams are used to explain refraction

A

wave front diagrams

240
Q

a wave front is found in a group of ………. waves travelling ……..

A

group of identical wave travelling together

241
Q

what is a wave front

A

an imaginary line that connects all the same points in a set of waves

242
Q

can wave fronts only be applied to longitudinal, transvers, or both types of waves?

A

BOTH

243
Q

wavefronts make it easier to visualise……

A

lots of waves moving together

244
Q

what do we do once we’ve drawn on the wavefronts onto the waves

A

remove the waves so we just have the wave fronts ( the lines connecting all the same points in a set of waves )

245
Q

explain what happens to wave fronts travelling at an angle when they go from air to glass

A

when parts of wavefronts move into glass, those parts slow down

246
Q

what happens when parts of wave fronts slow down on entering a new medium. why

A

-their wavelengths get smaller
because those parts of the wavefront move closer together
-waves bend towards the normal

247
Q

another word for when the waves bend towards the normal
is…

A

refracting

248
Q

what happens to wavefronts approaching along the normal into glass
2 points

A

waves slow down but do not change direction

249
Q

why do wave fronts approaching glass along the normal not change direction

A

because the whole wavefront slows down at the same time

250
Q

why do wavefronts that approach glass not along the normal refract

A

because some parts of the wavefront slow down first

251
Q

hot surfaces, like glowing coals, emit……

A

infrared radiation

252
Q

can humans see infrared radiation

A

no

253
Q

what is a Leslie’s cube used for

A

to see how much infrared is emitted from different surfaces

254
Q

how many different surfaces does a leslies cube have

A

4

255
Q

name the 4 different surfaces of a leslie’s cube

A

shiny metallic
shiny black
white
matt black

256
Q

RP 10 investigate how the amount of infrared radiation radiated by a surface depends on the nature of that surface.

list steps
x3

A

.fill leslie’s cube with hot water
.point infrared detector at each of 4 different surfaces
.record amount of infrared emitted

257
Q

important things to remember when recording amount of infrared on each surface of Leslie’s cube

A

keep same distance between Leslie’s cube and infrared detector

258
Q

why is keeping the same distance between the Leslie’s cube and infrared detector is important.

A

makes the measurements repeatable

259
Q

what surface emitts most infrared

A

matt black

260
Q

what surface emits least infrared

A

shiny metallic

261
Q

list the 4 materials on the leslie’s cube from which emits most infrared radiation to which emits the least infrared radiation

A

matt black
shiny black
white
shiny metallic

262
Q

what can be used to measure infrared radiaition if we don’t have an infrared detector

A

use a thermometer with the bulb painted black

263
Q

issue with using a thermometer with a black painted bulb instead of an infrared detector when comparing amount of infrared radiated by different surfaces
2 points

A

resolution of thermometer lower than infrared detector
the infrared detector is more likely to detect a difference

264
Q

define resolution

A

the smallest change that can be detected

265
Q

describe the equipment needed to measure the absorbance of infra red
by different surfaces

A

infrared heater,
metal plate on either side
one painted shiny metallic
other painted matt black
drawing pin attached to outer side of each
plate using vaseline

266
Q

how do you carry out the experiment to investigate how the amount of infrared radiation absorbed depends on nature of surface

A

turn on the heater (between the metal plates)
start the timer
record time it takes for vaseline to melt + pins to fall

267
Q

when investigating the amount of infrared radiation absorbed what happens to the metal plates as they absorb infrared

A

temp of plates increases as they absorb infra red

268
Q

will the drawing pin fall off the matt black or shiny metallic plate first + why

A

matt black
because matt black surfaces absorb more infrared than shiny metallic surfaces

269
Q

what conclusion can be draw from RP 10 investigating how the amount of infrared radiation absorbed or
radiated by a surface depends on the nature of that surface

A

matt black surfaces are better at absorbing and emitting infrared than shiny metallic surfaces
infrared is reflected from shiny metallic surfaces

270
Q

what colour light emitted when lithium is heated in a flame

A

red

271
Q

when lithium atoms are heated and give out a red light, what type of wave do they emit?

A

electromagnetic waves

272
Q

what happens when electromagnetic waves are generated or absorbed over a wide frequency range

A

changes take place in atoms and nuclei of atoms

273
Q

what happens inside atoms when they are heated

A

electrons move from one level to a higher energy level

274
Q

what happens when an electron moves back to its original energy level after being heated

A

it generates an electromagnetic wave- (eg. light)

275
Q

how can an electromagnetic wave be generated
x2

A

when an electron moves back to its original energy level
a change to the nucleus

276
Q

where do gamma rays originate from

A

changes in the nucleus of an atom

277
Q

where can gamma rays be emitted from

A

the nucleus of radioactive atoms

278
Q

when a gamma ray is emitted from the nucleus of an atom it means that the nucleus….

A

the nucleus has less energy than at the start

279
Q

what happens when electromagnetic waves are absorbed by atoms + give an example

A

the atom changes - eg electrons can change energy shells

280
Q

…….. waves can be emitted and …… over a ……. frequency range from radiowaves to ……….. rays

A

electromagnetic waves can be emitted and absorbed over a wide frequency range from radio waves to gamma rays

281
Q

hazards of ultraviolet waves on human tissue x2

A

increase risk of cancer
cause skin to prematurely age

282
Q

x-rays and gamma rays are both types of

A

ionising radiation

283
Q

what do xrays and gamma rays do to atoms when absorbed

A

knock electrons off atoms

284
Q

hazards of x-rays and gamma rays
x2

A

mutates genes which…
increases risk of cancer

285
Q

what does the damage caused by radiation depend on
x2

A

the type of radiation
the dose

286
Q

what is dose of radiation measured in ???

A

sieverts (Sv)
millisieverts (mSv)

287
Q

how can radio waves be produced

A

when electrons oscillate in electrical circuits

288
Q

what does oscillate mean

A

move back and forward

289
Q

can radio waves be absorbed.
if yes, give example.
if no state why not

A

yes,
an electrical circuit in an aerial

290
Q

what happens when radio waves are absorbed by an electrical circuit in an aerial

A

the electrons in the circuit oscillate

291
Q

when radio waves are absorbed by an electrical circuit, the electrons in the circuit also oscillate. What is now created
2 points

A

an alternating current
with the same frequencies as the radio waves

292
Q

radiation dose is the measure of….

A

the risk of harm from body exposure to radiation

292
Q

radiation dose is the measure of….

A

the risk of harm from body exposure to radiation

293
Q

radio waves are used to transmit…..
x2

A

radio &
terrestrial TV signals

294
Q

what is terrestrial tv

A

tv received using an aerial

295
Q

why are radio waves useful

A

travel long distances before being absorbed
this is
reflect off layer of charged particles in atmosphere

296
Q

what specifically can longer wavelength radio waves do

A

spread out between hills

297
Q

*not on spec, delete if u want *
what is it called when waves can spread out between hills

A

diffraction

298
Q

what is a layer of charged particles in the atmosphere called

A

ionosphere

299
Q

radio waves can travel long distances around the earth before being absorbed. what is the reason for this

A

because they reflect off layers of charged particles in atmosphere

300
Q

uses of microwaves
x2

A

heat food
communicate with space satelites

301
Q

why are microwaves used to heat food

A

most foods contain many water molecules
water molecules absorb energy of microwaves

302
Q

what does the energy of microwaves cause

A

the temp of food to increase

303
Q

why are microwaves used to communicate with satelites in space

A

because microwaves pass through earths atmosphere without being reflected or refracted

304
Q

uses of infrared x3

A

electrical heaters
ovens (cook food)
infrared cameras

305
Q

why is infrared used in electric heaters and ovens
give an example in terms of heaters

A

the energy of infrared is easily absorbed by the surface of objects
- infrared from heater absorbed by objects in room

306
Q

example of what infrared cameras are used for

A

check for heat loss

307
Q

use of visible light

A

fibre optic communications

308
Q

what are optical fibres

A

very thin glass strands

309
Q

what do we do to the optic fibres to carry info

A

transmit pulses of light down fibres
use these pulses to carry info

310
Q

what are optical fibres used for

A

carry telephone signals
carry cable tv signals

311
Q

does visible light have short or long wavelength.
why is this useful.

A

short wavelength
it can carry alot of info

312
Q

uses of ultraviolet light

A

energy efficient lamps
sun tanning

313
Q

does ultraviolet light have short or long wavelength

A

short

314
Q

what carries more energy, visible light or ultraviolet light?

A

ultraviolet light

315
Q

what happens inside an energy efficient light bulb

A

ultraviolet light is created inside the bulb
-energy of ultraviolet is absorbed by the internal surface of the bulb
-it is converted to visible lightultraviolet light is created inside the bulb
-energy of ultraviolet is absorbed by the internal surface of the bulb
-it is converted to visible light

316
Q

in an energy efficient bulb,
-ultraviolet light is created inside the bulb
-energy of ultraviolet is absorbed by the internal surface of the bulb
-it is converted to visible light

Why is this good

A

It requires less energy than a normal light bulb

317
Q

hazards of ultraviolet light x2

A

increase risk of skin cancer
premature skin aging

318
Q

uses of x rays and gamma rays

A

medical imaging
treatments

319
Q

example of what x-ray can detect in medical imaging

A

broken bone

320
Q

example of what gamma ray can detect in medical imaging

A

cancers

321
Q

both x-rays and gamma rays are very ……

A

penetrative

322
Q

what does a penetrative wave mean

A

pass easily through body tissue

323
Q

why can we see x-rays on x-ray images

A

because x rays absorbed by bones

324
Q

example of a medical treatment that x-rays and gamma rays can be used in

A

to treat cancer

325
Q

what is the idea of refraction

A

waves change direction when they change speed, going from one medium to another

326
Q

describe shape of convex lenses

A

thicker at centre than edges

327
Q

what is the symbol for convex lens

A

straight line down with arrow on both ends

328
Q

key feature of all lenses

A

they refract light

329
Q

what happens to the light ray as it passes into the lens

A

it bends towards the normal

330
Q

what happens to the light ray as it passes out of the lens

A

bends away from normal

331
Q

when parallel rays of light pass through a convex lens what are the two main things that happen

A

central ray passes through lens without being refracted

all other rays refract and are focused at a point

332
Q

why is the central ray not refracted when it enters a convex lens

A

because this ray passes directly along the normal

333
Q

when the central ray passes through the lens without being refracted, we say that this ray ……

A

is passing along the principal axis
-centre of the lens

334
Q

when parallel rays pass through a convex lens all rays (except central ray) refract and are focus at a point.
what is this point called?

A

the principle focus

335
Q

what is the symbol for the principle focus

A

F

336
Q

what do you call the distance from the centre of the lens to the principle focus

A

focal length

337
Q

does the focal length change with different convex lenses

A

yes

338
Q

the focal length depends on

A

the strength of the lens

339
Q

when parallel rays pass through a convex lens , which rays meet at the principle focus

A

all the rays, even the central ray

340
Q

how to draw ray diagram for convex lens
4 points
what will already be there:
-straight line horizontally- the principle axis
-convex lens symbol going down through centre of principle axis

A

-place object minimum 2 focal lengths away from lens
-draw diagonal line from top of object through centre of lens- without changing direction
- draw line parallel to pricipal axis from top of object across to lens
-when line hits lens, its refracted through principal focus.
where two lines meet shows top of image

341
Q

3 key features of the ‘image’ made through a ray diagram

A

image is diminished
-(smaller than object)
image is inverted
-(upside down)
this is a real image

342
Q

what is meant when an image is a ‘real image’
2 points

A

the rays actually meet at a point
if you placed a screen there you would see the image in the screen

343
Q

what are the properties of the image formed in a ray diagram when object is between one focal length and two focal lengths

A

magnified image ( larger than object)
inverted
image is real

344
Q

the properties of an image depend on what

A

the distance between the object and the lens

345
Q

3 properties of image if object is more than 2 focal lengths from the lens

A

diminished
inverted
real

346
Q

3 properties of image if object is between 1 and 2 focal lengths from the lens

A

magnified
inverted
real

347
Q

magnifying glass works when an object is …….
a) between 1 and 2 focal lengths from the lens
b) less than 1 focal length away from the lens
c)more than 2 focal lengths away from the lens

A

B

348
Q

if an object is less than 1 focal length away from the lens you could also say that the object is very ……. to the lens

A

close/near

349
Q

describe ray diagram for magnifying glasses

A

-object is between 1 focal length and the lens
-draw line (ray) from top of object through centre of lens- doesn’t change direction
-another line(ray) from top of object, parallel to principle axis
-this line (ray) then passes through principle focus
–rays/lines don’t meet
-draw dotted line to extend rays/lines behind object
-where they meet shows image position

350
Q

what do the lines we draw in ray diagrams represent

A

light rays

351
Q

3 key properties of image formed by ray diagram of magnifying glass

A

magnifies
not inverted(image same way up as object)
image is virtual

352
Q

how can you tell that the image formed in a ray diagram of a magnifying glass is virtual

A
  • rays don’t meet at a point
    -we could not see this image on a screen
353
Q

when is the only time that a convex lens produces a virtual image

A

when it is used as a magnifying glass

354
Q

what must happen to make a convex lens be used as a magnifying glass

A

the object is less than 1 focal point away from the lens

355
Q

unit for magnification
why

A

no units
its a ratio

356
Q

magnification = image height / object height
what are the units for height

A

cm
mm

357
Q

the image formed by a convex lens can be either……. or……

A

real
virtual

358
Q

describe concave lens

A

thicker at edges than centre

359
Q

what does a convex lens do in brief

A

focus parallel rays of light to a point- the principal focus

360
Q

describe symbol for concave lens

A

straight line down. v on top, upside down v on bottom
v
l
l
^

361
Q

what happens to light rays that hit a concave lens

A

light rays diverge

362
Q

light rays diverge when they hit a concave lens. Another way to describe what concave lenses do to light rays is to say that concave lenses make

A

concave lenses make light rays spread out

363
Q

if the lines leaving the concave lens are plotted back behind the lens, what do we find

A

the lines come to a point

364
Q

the point where the rays meet in a ray diagrams is called….

A

the principle focus

365
Q

do concave lenses focus the light rays at the principle focus. explain your answer

A

no, the light rays only appear to be coming from principle focus

366
Q

describe ray for concave lens

A

-draw diagonal ray from top of object through centre of lens, without changing direction
-another ray from top of object
passes through lens and then refracted out
-draw dotted line so this ray appears to come from principle focus
-where dotted line and first line drawn meets show image position

367
Q

describe 3 properties of image made in ray diagram for concave lens

A

image diminished
image right way up
image is virtual

368
Q

why is the image made in a ray diagram for concave lenses considered virtual

A

because rays do not actually cross
if we place a screen where the image appears, we would not see an image

369
Q

with a concave lens the image will always be…….
1
2
3

A

diminished
right way up
virtual
(any order)

370
Q

during reflection the angle of reflection is…….

A

the same as the angle of incidence

371
Q

define specular reflection

A

reflection from a smooth surface in a single direction

372
Q

what does specular reflection do

A

produce an image

373
Q

define diffuse reflection

A

reflection from a rough surface causes scattering

374
Q

does diffuse reflection produce an image

A

no

375
Q

what is white light

A

a mixture of all the different colours

376
Q

what happens to white light when passed through a prism

A

it splits into a spectrum

377
Q

what 2 things does each colour in the visible light spectrum have

A

own narrow band of wavelength
own narrow band of frequency

378
Q

what does the colour of an object depend on

A

which wavelengths of light are reflected, transmitted or absorbed

379
Q

how do colour filters work

A

by absorbing certain wavelengths (and colour) and transmitting other wavelengths (and colour)

380
Q

what is meant by saying a colour filter transmitts a wavelength

A

allows the wavelength through

381
Q

what happens when you shine white light onto a red filter
(this is applicable to any colour from the visible light spectrum)

A

-filter absorbs all colours of visible light except from red
-only red light is transmitted through the filter

382
Q

objects that transmit light can be 1 of two things. What are these

A

transparent
translucent

383
Q

what do translucent objects do
what is the effect of this

A

scatter light rays.
can’t see through them clearly

384
Q

what do we call objects that we cannot see through at all

A

opaque

385
Q

why do white objects appear white

A

they reflect all of the wavelengths of visible light equally

386
Q

why do black objects appear black

A

they absorb all the wavelengths of visible light

387
Q

how is the colour of an opaque object determined

A

by which wavelengths of light (which colours) are more strongly reflected and which are absorbed

388
Q

white light shines onto a blue object, why does object have blue colour

A

all the colours are absorbed- except from blue- which is reflected

389
Q

there is a red object on table
and red filter above object
white light shines onto filter
what happens

A

red filter absorbs all the colours of white light, apart from red
red is transmitted
red light reflects off red object
so object appears red

390
Q

there is a green object on a table
and red filter above it
white light shines onto filter
what happens

A

red filter absorbs all colours of white light except red
red is transmitted
green object absorbs all the red light thats transmitted instead of reflecting it
green object appears black as its not reflecting any light

391
Q

when does an opaque object appear black

A

when it does not reflect any light

392
Q

what surfaces are the best emitters and absorbers of infrared radiation

A

matt black

393
Q

true or false+ why

objects below 5 degrees do not emit infrared radiation

objects above 600 degrees do not absorb infrared radiation

A

FALSE
All objects emit AND absorb infrared REGARDLESS of temperature

394
Q

in a given time, which object will emit more infrared, a cooler object or a hotter one

A

a hotter object

395
Q

what do the wavelength and intensity of radiation depend on

A

the temp of the object

396
Q

how does the size of the wavelength of the radiation depend on the temp of the object

A

as the object gets hotter, it emits more short wavelength radiation

397
Q

…… hot objects emit ….. wavelength ….. than ….. objects

A

very hot objects emit shorter wavelength radiation then cooler objects

398
Q

how are the intensity of radiation and wavelength related

A

shorter wavelength means higher intensity of radiation

399
Q

why do very hot objects produce visible light

A

because as an object gets hotter, it emits more short wavelength radiation

400
Q

what happens to the intensity of radiation at higher temperature

A

intensity increases at higher temps

401
Q

define a perfect black body

A

an object that absorbs all the radiation incident on it

402
Q

a black body does not ….. or ….. any radiation

A

A black body does not reflect or transmit any
radiation.

403
Q

an object than ……. radiation well will also …… radiation well

A

absorbs
emits

404
Q

a perfect black body is an object that absorbs all the radiation incident on it. Since a good absorber of radiation is also a good emitter of radiation, a perfect black body would be

A

the best possible emitter

405
Q

what will an object do if warmer than surroundings

A

emit more radiation than it absorbs

406
Q

if an object emits more radiation than it absorbs, what will happen to the object

A

it temp will decrease

407
Q

what will an object do if cooler than its surroundings

A

absorb more radiation than it emits

408
Q

if an object absorbs more radiation than it emits, what will happen to the object

A

its temp increase

409
Q

what will an object do if its at a constant temp

A

absorb and emit radiation at the same rate

410
Q

what are the only two ways earth can lose / gain energy

A

emitting radiation
absorbing radiation

411
Q

what does the sun do to radiation
what type of radiation
example of that type of radiation

A

emits radiation
short wavelength radiation
eg visible light

412
Q

what can happen to the radiation emitted by sun
what does this cause

A

reflected by clouds
absorbed by earths surface
causes temp of earth to increase

413
Q

what happens to infrared radiation on earth

A

emitted back into space
some gets trapped by greenhouse gases

414
Q

human activity is increasing the levels of

A

green house gases in the atmosphere

415
Q

what is the effect of increased greenhouse gases

A

more heat energy trapped in atmosphere
less radiated into space

416
Q

what factors other than greenhouse gases affect amount of energy radiated from earth

A

amount of cloud cover

417
Q

why are cloudy nights warmer than clear night

A

clouds reflect infrared back to earth
( prevent infrared from being radiated to space)

Physics (8 decks)

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