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Physics > T12-Waves In Action > Flashcards

T12-Waves In Action Flashcards

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1
Q

Sound waves

A

-Sound is a longitudinal wave .
-When sound waves move through the air , the air prticles vibrate from side to side .
-These vibraitons can pass from ONE MEDIU to another (air—> soild)

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2
Q

A microphone

A

-One of the key parts is a papercone .
-When sound waves hit the cone , this causes it to vibrate .
–The microphone then converts this to electrical signals .

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3
Q

The Ear Drum

A

-Soundwaves are funnelesd into the ear , where they hit the eardrum .
-The ear drum is a thin membrane .
-The soundwaves cause the ear durm and other parts of the ear to vibrate .
-This cuases the sensation of sound .

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4
Q

What can soundwaves in the air trigger ?

A

They can trigger vibrations in soilids .
-This only works for over a limited range of frequencies .
-Partl because of human hearing having a freuneunxy of 20Hz to 20,000 Hz
-Frequnecies outisdeo f that may not be bale t ocause the eardurm to vibrate.

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5
Q

What can happen when waves move from one miedum to another .

A

-Their speed can change
(soundwabes travel much aster in soilds then in glasses).
—>as the particles in a soild are much closer together .
-This means the vibrations can pass more easily beween them.

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6
Q

When waves speed changes as waves pass from one medium to aother .

A

Their wavelength also changes .
FREQUENCY DOES NOT CHANGE ,w hen a wave changes medium .
-AS WAVES WOULD HAVE TO BE CREATED OR DESTROED AT THE BOUNDARY this is not possible .

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7
Q

How can we view features of soundwaves?

A

By connecitng mcirophone - to a cathode ray oscilloscope
PROBLEM; shows sound waves as transverse ways (not correct remember soudwaves are longitidunal

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8
Q

High Frequenxy

A

High Pitch

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9
Q

Low frequency

A

Low pitch

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10
Q

Small amplitude

A

Quiet sound

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11
Q

Large amplitude

A

Loud sound

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12
Q

Sounswaves can only move thourgh a medium becuase…

A

Soundwavs move by particles vibraing . Soudnwaves cnnot pass thorugh a vacuum as there are no particles .

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13
Q

Soundwaves (like light) can also be reflected

A

we call reflected sound an echo.

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14
Q

What is ulatrasound

A

Ultrasound is soundwaves with a frequency higher than the upperlimit of human hering .
-SO the frequnecy of ultrasound is at lest 20,000 Hz .

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15
Q

KEY baout ultrasound

A

ultrasound partiall ty reflect at the boundayr between two different denisities .
-If we calcuolate the itme it needs for the ultrasound pulse to leve the porbe and bounce off the object nd derected byt he porbe , we cn calculte the DISTANCE BETWEEN hte probe and the object..

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16
Q

Ultrasound scanner porduce images of internal orgas usc as the kidney and heart .

A

This owrks for any organ that IS NOT surrounedby boen . Can also use for ltrasound ot porduce images of a foetus .

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17
Q

Advantage of ultrasound to XRAYS

A

-Ultrasound is much safer than x-rays .
-As ultrasound does not cause mutation and does not increase the risk of cancer .
-Ultrasound allowed in inudstrial imagery (can pipe) -Ultraosund can be used ot deect hidden defect or porblems witha weld .

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18
Q

do question in book

A

time 1.2s
speed 1600,/s
calcultr distancr

-Hvr ot Half the distance a the calcualtion is actually the TOTAL DISTNCE FOM THE SEABED ND BAC K , so jus to find the depth divide ASNWER BY 2.

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19
Q

The crust

A

-Outside of the Earth is solid crust .
-The crust is very thing with a maximum dpetho f around 50Km . #

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20
Q

The mantle

A

-Under ht ecurst we have the mantle - the mantle is soild (perts of the mantle move slwoly upper part but we still call soild.)

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21
Q

the core

A

outercorse is liquid inner core is soild .

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22
Q

How do scienists know the earth has this inetoer sturctur , you cannot direclyty observe tihs

A

EARTHUAKES - sudden movment between the tectonic paltes in the Earth’s curst .
-Causing seismic waves ,w hic h carry energy from the Earthquake .
-These seismic waves can pass thruogh the Earth + can be detected by different coutnires (patern of these give us the ino bt inerior of earth .)

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23
Q

There are two main types of longitiduinal waves

A

P waves - longitiudinal waves
- Primary waves they cuase the intial tremors.) and they move up and down so aren’t s dangerous as s waves .
-primary waves can pass thorugh soilds and liquids .
-Pw aves travel faste thna s waves

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24
Q

S waves

A

s waves are transverse waves , and can onlyt rave through soilds .

-Sesiometers oon the Eartj;s surface now can detect the seismic wavs after they hve passed htourgh the Earth .

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25
Q

Why do seismic waves travel in curved paterns

A

due to denisty changes

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26
Q

s waves can be detected anywhere on the hgihglighted part of the earths sufrace

A

-gthere are large partso f earth where no s waves are detected , these are SWAVE SHADOWS .

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27
Q

WHAT ARE THE S WAVES SHADOWS CAUSED BY

A

The fact that s waves canot pass thorugh liquid . This tells scienitsts the Earth must contain a liquid core .

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28
Q

Pwaves cna be detecred anwyhere on the highlgihted region

A

Large prts if tge ertg wher ep waves cannot be detetce d, pwave shdow waes .

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29
Q

what are p wave shadow zones caused by

A

the fact that p waves travel faster in soilds than in liquids .
-p waves SLOW DOWN as they enter the liquid outer case .
-This causes them to REFRACT (change direction)
-They also refract gweb tget keace the outercore .
-This CONFIRMS that the outercore is liquid .

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30
Q

Sometimes faint p waves can be detected in the p wave shadow zone .

A

This was used by scientists to show tht the Earth also contains a solid inner case .

-sciensits measured the seisic waves fromt housands of Earthquake .
-They have used this to work out the thicknesso f the curst nd mantle and outer and inner core .

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31
Q

What is white light

A

It is a mixure of all the colours , if we pass white light thorugh a prism then it splits into a spectrum .

32
Q

Each colour has a narrow band of wavelength and frequency .

A

The COLOUR of an objetc depends on whcih w avlengths f ligha re reflected , transmitted or absorbed .

33
Q

How do coloured filtrers work ?

A

By absorbing specific wavelegnths and by transmitting (allowing thorugh) other waavelengths .

34
Q

red filter

A

-iIf ou shine white light onto the iflter , filrter absorbs the colour of visible light apart formr ed .
-So onl red light is transmitted htourgh the filter.

35
Q

green filter

A

all of the oclours re absorbed aprt formg reen . gren is trnsmitted htourgh the iflter .

36
Q

Objects that transmilight re iether transparent or translucent.

A

-You can EASILy see thorugh transparent objects .
-Translucent objects scter the light rys so we cannot see thorugh them clely .

37
Q

Objects thAt we cannot see thorugh at all are poaque

A

-white light shines onto white object .
-wHITEO BJECTS PPAEAR WHITEBECAUSE THEY EFLECT ALL THE WAVELENGTHS OF VISILE LIGHT EQUALLUY .

38
Q

White light shining onto a black object

A

-Black objects appaear black because hey absorb all the wavelengths of visible lgiht .

39
Q

white light shining onto a red object

A

Red obejcts absorb ll the colours of white light apart from red which is RFLECTED .
-hENCE WHY OBJECT HS RED LIGHT
(Same fir vkue as al the oclours are absorbed apart from blue which is relfetced .)

40
Q

combining coloured objects with coloured filters .

A

red object + red filter
-red filter absorbs all fo the colours of white apart from the red which si transmitted .
-Red light cannot reflect off the real objects , o the objetc onw ppears red .

41
Q

green objects or red filters

A

red filters allow the red lightt o be transmitted .
-However , the green onject completley absorbs the red light so none of it is reflected .
-In this cause the green object will aper balck as i is reflecting no light at all .

42
Q

What are we describing in this RQP ?

A

-How to investigte the reflection of light bby different types of surfce + the refraction o flight by different substances .

43
Q

Equipiment needed for this rqp ?

A

Ray box , lens and slit
-This produces a narrow ray of light .
-Ray boxes do get hot , so it is important to switch them off when they are not being use d .
-COULD DO this practical with a ser , nbut this can be dangerous , ray box is afer

44
Q

S1 of RQP

A

-Take a piece of A3 paper and draw a straight line , down the center using a ruler .

45
Q

S2 of rqp

A

use a protractor to draw lines at right angles . This is the nromal (label N)

46
Q

Stage 3 of rqp

A

Now place a glass bxo agaisnt hte first line so tht the normal is near the center of the block .

47
Q

Stage four of rqp

A

draw around the glass block , mke sure to turn out all the lights in the room .

48
Q

Stage 5 of rqp

A

use the ray box to direct a ray of light so it hits the block at the normal .
-This is the INCIDNENT RAY .
-The angle between the incident ray and normal is the ANGLE OF INCIDENCE .

49
Q

Stage 6 of RQP

A

-Adjust the ray box to chnage the anlge of incidience .
-At a certian angle , we cansee a ray REFLECT fromt he surface of the block .

50
Q

Stage 7 of rqp

A

we ca also see another ray lavin the block from the opposite side , this is the transmitted ray .

51
Q

Stage 8 of rqp

A

Mark the path of the transmitted ray a nd incidnet ray and relfected ray with crosses

52
Q

Stage 9 of rqp

A

turn on room lights and switch of the ry box . GThen remove glassbox .

53
Q

Stage 10 of rqp

A

Draw in the reflected ray and incidnent ray , then daw int he transmitted rya so oit meets the position of the block .

54
Q

Stage 11 of rqp

A

draw a line to show the path of the transmited ray though the glass block

55
Q

stage 12 of rqp

A

use a portractor to measure the angle of incidnence and relfectionad refraction .
-The angle of refraciton is the anlge between the nromal and the path of the transmittd ray htourgh the block .

56
Q

stage 13 of rqp

A

do the whole epxeriment again using different material like (perspex)

57
Q

FNDINGS OF RQP (1)

A

-Angles of incidence and reflection are the same for btoh glss and perspex x.
-As the nlgres of incidence and reflection do not depend on the materials .

58
Q

Findings of rqp (2)

A

-As the anlge of refraction is different for different materials

59
Q

convex lenses

A

convex lenses are thicker at the center than at the edges .

60
Q

lenses

A

lenses refract light , the light rays bend towards hte normal when it passes into the lens .
-and way from the normal , when it passes out of the lens .

61
Q

parallel rays passing thorugh the ocnvex lens
check sheet

A

1.central ray passes through the lens without being refracted ,a s the ray is passing directly passing along the normal .
-This ray is passing along the PIRNCIPAL AXIS (the center of the lens .)
-

62
Q

stage 2

A

-all the other rays refract and are focused ona point –> this is called the principal focus (F) .

63
Q

stage 3

A

The distance from the center of the lens to the principel focus is called the focal length .

-Different covnex lenses have got different focal lenfths depending on the strenght of lens .

64
Q

Ray diagram for an object at least two focal length away from the lens . (1)

A

-draw a line to the top of the object passing stright through the center of the lens without chnign direciton .

65
Q

Ray diagram for an object at least two focal length away from the lens . (2)

A

dRAW ANOTHER LINE FROM the top of the object , this line runs parallel to the principal axis .

66
Q

Ray diagram for an object at least two focal length away from the lens . (3)

A

when this line htis the lens it is refrcted htorugh the prinicpal focus .

67
Q

Ray diagram for an object at least two focal length away from the lens . (4)

A

Where the two lines meet , get the top of the image .

Key properties of the oimage

-The image is SMALLER than the objects scientists ay the image is diminished .
-The image is inverted (uspide down .)
-This is a REAL IMAGE - as the rays actually meet at a point .
-If we ple a scrren here we would see the imge on the screen .

68
Q

object thagtis between one ad two focal lengths from the lens
Check sheet

A

Same thin for one two and three .
However the PROPERTIES OF THE IMGE CHANGE .
-The image is larger thn the objec it has been MAGNNFIIED .
-Image is inverted
Image is real (MEET T A POINT )

69
Q

the properties of i=an image depend on …

A

THe distance ebtween object and lens .

70
Q

Concave lenses

A

thicker t the edges than at the center
-Rau pf light hit the concsave lens nd make the light ryas spread out the light rays DIVERGE //

70
Q

Concave lenses

A

thicker t the edges than at the center
-Rau pf light hit the concsave lens nd make the light ryas spread out the light rays DIVERGE //

71
Q

Concave lenses

A

thicker t the edges than at the center
-Rau pf light hit the concsave lens nd make the light ryas spread out the light rays DIVERGE //

72
Q

-iF WE PLOT THE LINES BEHIDN THE LENDS , WE CN SEE THAT THEYC OME TO A POINT .

A

-wE CN SEE THIS IS THE PRINCIPAL FOCUS 9f)
key ; A CONCAVE LENS IS NOT Actually FOCUSING THE LIGHT at the princippal focus , the light rays onlly APPEAR to be coming fro the principl foucs

73
Q

Ray diagram for concave lens (1)

A

-dra a ray from the top of the object passing though the center without chaning direction .

74
Q

ray diagram for concave lens (2)

A

draw antoehr ray from the top of the object .
-This psses thoruh the lens and is refracted .
-The ray mt apper to come form the principal focus . 9Draw a dotted line to show this .0

75
Q

ay diagrams for concave lens for (3)

A

-Where these lines meet show the posiiton of the image ,
-KE POINTS OF THE IMAGE
-Image is DIMINISHED (Smaller than the object )
-Image is the right ay up .
THe image is VIRTUAL AS THE RAYS DO NOT ACTUALLHY MMET THEY ONLAY APPER TO .
-iF WE PLAC E A SCRRENE WHERE THRE IMAGE IS ,W E OWULD NOT SEE A N IMAGE ON THE SCREEN .

Physics (20 decks)

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