WAVES #2 Flashcards
OPAQUE objects do not…
transmit light
transparent and translucent objects ….
do transmit light
why does a white object appear white`
reflects all of the white light
what does white light consist of
ROYGBIV
WHY di black objects appear black
they absorb all of the colours in the visible light
why do objects appear a colour eg red
a object appears red because it has absorbs all the colours of light except red which it is reflecting
what do colour filters do
colour filters filter out different wavelengths of light so that only certain colours are transmitted- the rest are absorbed
what would you see if you looked at a red object through a blue filter
the object would look black
a student looks at a red bag with a green buckle through a colour green filte. describe whay the student will see
the red bag is reflecting red light and the green buckle is reflecting green light
as it is a green filter only green light will be able to pass through
this means the buckle will appear green as the light reflected can pass through
howeber the bag will appear black because the filter doesn’t allow through the red light being reflected by thr bag
every object emits and absorb
infrared radiation
the hotter the object the more
infrared radiation it emits
an object that is hotter than its surroundings emits more Infrared radiation than it
absorbs. WHICH COOLS IT DOWN
an object that is COLDER than its surroundings emits LESS Infrared radiation than it
emits. which warms it up
objects at a constant temperature emits
infrared radiation at the same rate theyre absorbing it
what are sound waves caused by
vibrating objects
explain in terms of vibrations what happens when a sound enters your ear
air particles move back and forth creating pressure on your ear drum
this change in pressure causes the ear drum to vibrate
these vibrations pass from your ear drum to the inside of your ear
these vibrations are turned into electrical signals which ae sent to your brain so you can hear the sound
what are echoes
reflected sound waves
how is a sound wave created in a speakee
the paper diaphragm in a speaer vibrates back and forth
which causes the surrounding air to vibrate creating compressions and rarefactions
this creates a sond wave
why cant sound travel in space
because it mostly a vacuum which means there no available particles to vibrate
what is ultrasound
ultrasound is sound with frequencies higher than 20,000hz
what is infrasound
anything below 20hz- unable for us to detect
what is the speed of sound in air
330m/s
what is the speed of sound in water
1500m/s
equation when working out ultrasound
speed=distance/time (divided by 2)
what do you always have to remember for ultrasound calculations
to divide by two
what happens when ultrasound hits a boundary
the ultrasound wave gets partially reflected
pre natal scanning
in order to see unborn babies an ultrasound wave with a frequency between 2 and 10 MHz is made an transmitted into the mother
the wave is partially refleted when it meets a boundary between two different media
these refelctions are collected and interpreted as a picture
adv of untrasound scans
non invasive
accurate
non ionising
image is available immediately
dis of ultrasound scans
images deeper in the body results in progressively poorer resolution
using ultrasou[nd to treat kidnet stones
a high powered ultrasound wwave is used
stones vibrae until the break apart and easily passed out of the body via the the ureatha
the diagram shows how ultransonic waves can bee used to clean a watch suggest how
the oscillator vibrates causoing the fluid to knock the dirt off the watch
state two features of ultrasound
very high frequency waves
higher frequency than human hearing range
diagram shows an ultrasound transmitter
the block has an internal crack
explain why pulse a and b occur
when the ultrasound goes through the block it sends out three reflections when it enters, when it hits the crack and when it leaves, this is because it has been partially reflected back as it has hit a different boundary
pulse a occurred because it has changed density so it has sent a reflection back
what are the two types of seismic waves
p waves and s waves
what are p waves
p waves are longitudinal they travel through solids and liquids they travel faster than s waves can travel through the earth core they are bent by changing the density of the rock
what are s waves
s waves are transverse
they only travel through solids
theyre slower than p waves
they are bent by changing the density of the rock
what are the two types of surface waves
love wave
Rayleigh wave
where do the surface waves only travel
in the earths crust
what is a black body
is an object that absorbs all of the radiation that hits it, no radiation is reflected or transmitted
as the temp of an object increases the intensity
of every emitted wavelength increases
the hotter an object is the shorter its
peak wavelength
the peak wavelength of the sun is 500nm
the peak wavelength of another star is 850nm
which star is hotter
the sun is hotter because the hotter an object is the shorter its peak wavelength
can pwaves travel through the earths core
yes
csn s waves travel through the outer core
no
