T12-Waves In Action Flashcards
Sound waves
-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)
A microphone
-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 .
The Ear Drum
-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 .
What can soundwaves in the air trigger ?
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.
What can happen when waves move from one miedum to another .
-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.
When waves speed changes as waves pass from one medium to aother .
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 .
How can we view features of soundwaves?
By connecitng mcirophone - to a cathode ray oscilloscope
PROBLEM; shows sound waves as transverse ways (not correct remember soudwaves are longitidunal
High Frequenxy
High Pitch
Low frequency
Low pitch
Small amplitude
Quiet sound
Large amplitude
Loud sound
Sounswaves can only move thourgh a medium becuase…
Soundwavs move by particles vibraing . Soudnwaves cnnot pass thorugh a vacuum as there are no particles .
Soundwaves (like light) can also be reflected
we call reflected sound an echo.
What is ulatrasound
Ultrasound is soundwaves with a frequency higher than the upperlimit of human hering .
-SO the frequnecy of ultrasound is at lest 20,000 Hz .
KEY baout ultrasound
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..
Ultrasound scanner porduce images of internal orgas usc as the kidney and heart .
This owrks for any organ that IS NOT surrounedby boen . Can also use for ltrasound ot porduce images of a foetus .
Advantage of ultrasound to XRAYS
-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 .
do question in book
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.
The crust
-Outside of the Earth is solid crust .
-The crust is very thing with a maximum dpetho f around 50Km . #
The mantle
-Under ht ecurst we have the mantle - the mantle is soild (perts of the mantle move slwoly upper part but we still call soild.)
the core
outercorse is liquid inner core is soild .
How do scienists know the earth has this inetoer sturctur , you cannot direclyty observe tihs
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 .)
There are two main types of longitiduinal waves
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
S waves
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 .
Why do seismic waves travel in curved paterns
due to denisty changes
s waves can be detected anywhere on the hgihglighted part of the earths sufrace
-gthere are large partso f earth where no s waves are detected , these are SWAVE SHADOWS .
WHAT ARE THE S WAVES SHADOWS CAUSED BY
The fact that s waves canot pass thorugh liquid . This tells scienitsts the Earth must contain a liquid core .
Pwaves cna be detecred anwyhere on the highlgihted region
Large prts if tge ertg wher ep waves cannot be detetce d, pwave shdow waes .
what are p wave shadow zones caused by
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 .
Sometimes faint p waves can be detected in the p wave shadow zone .
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 .
What is white light
It is a mixure of all the colours , if we pass white light thorugh a prism then it splits into a spectrum .
Each colour has a narrow band of wavelength and frequency .
The COLOUR of an objetc depends on whcih w avlengths f ligha re reflected , transmitted or absorbed .
How do coloured filtrers work ?
By absorbing specific wavelegnths and by transmitting (allowing thorugh) other waavelengths .
red filter
-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.
green filter
all of the oclours re absorbed aprt formg reen . gren is trnsmitted htourgh the iflter .
Objects that transmilight re iether transparent or translucent.
-You can EASILy see thorugh transparent objects .
-Translucent objects scter the light rys so we cannot see thorugh them clely .
Objects thAt we cannot see thorugh at all are poaque
-white light shines onto white object .
-wHITEO BJECTS PPAEAR WHITEBECAUSE THEY EFLECT ALL THE WAVELENGTHS OF VISILE LIGHT EQUALLUY .
White light shining onto a black object
-Black objects appaear black because hey absorb all the wavelengths of visible lgiht .
white light shining onto a red object
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 .)
combining coloured objects with coloured filters .
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 .
green objects or red filters
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 .
What are we describing in this RQP ?
-How to investigte the reflection of light bby different types of surfce + the refraction o flight by different substances .
Equipiment needed for this rqp ?
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
S1 of RQP
-Take a piece of A3 paper and draw a straight line , down the center using a ruler .
S2 of rqp
use a protractor to draw lines at right angles . This is the nromal (label N)
Stage 3 of rqp
Now place a glass bxo agaisnt hte first line so tht the normal is near the center of the block .
Stage four of rqp
draw around the glass block , mke sure to turn out all the lights in the room .
Stage 5 of rqp
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 .
Stage 6 of RQP
-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 .
Stage 7 of rqp
we ca also see another ray lavin the block from the opposite side , this is the transmitted ray .
Stage 8 of rqp
Mark the path of the transmitted ray a nd incidnet ray and relfected ray with crosses
Stage 9 of rqp
turn on room lights and switch of the ry box . GThen remove glassbox .
Stage 10 of rqp
Draw in the reflected ray and incidnent ray , then daw int he transmitted rya so oit meets the position of the block .
Stage 11 of rqp
draw a line to show the path of the transmited ray though the glass block
stage 12 of rqp
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 .
stage 13 of rqp
do the whole epxeriment again using different material like (perspex)
FNDINGS OF RQP (1)
-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 .
Findings of rqp (2)
-As the anlge of refraction is different for different materials
convex lenses
convex lenses are thicker at the center than at the edges .
lenses
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 .
parallel rays passing thorugh the ocnvex lens
check sheet
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 .)
-
stage 2
-all the other rays refract and are focused ona point –> this is called the principal focus (F) .
stage 3
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 .
Ray diagram for an object at least two focal length away from the lens . (1)
-draw a line to the top of the object passing stright through the center of the lens without chnign direciton .
Ray diagram for an object at least two focal length away from the lens . (2)
dRAW ANOTHER LINE FROM the top of the object , this line runs parallel to the principal axis .
Ray diagram for an object at least two focal length away from the lens . (3)
when this line htis the lens it is refrcted htorugh the prinicpal focus .
Ray diagram for an object at least two focal length away from the lens . (4)
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 .
object thagtis between one ad two focal lengths from the lens
Check sheet
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 )
the properties of i=an image depend on …
THe distance ebtween object and lens .
Concave lenses
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 //
Concave lenses
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 //
Concave lenses
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 //
-iF WE PLOT THE LINES BEHIDN THE LENDS , WE CN SEE THAT THEYC OME TO A POINT .
-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
Ray diagram for concave lens (1)
-dra a ray from the top of the object passing though the center without chaning direction .
ray diagram for concave lens (2)
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
ay diagrams for concave lens for (3)
-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 .
