Sound and light Flashcards
What is a sound wave
An invisible wave that travels through using vibrations that make the air molecules move through the air to reach the ear
What do you call the space sound travels through
A medium
What medium does sound travels through quickest and why
Sound travels through solids quickest because the particles are closer together so the wave distance is shorter
Why can’t sound travel through vacuums
There is no medium for it to travel through
Are waves a matter
No waves are just a transfer of energy
What are vibrations also known as
Oscillation
The louder the sound the …
The higher the amplitude
What does a low amplitude sound have
Less energy resulting in a smaller range of movement through the air molecules
What are up and down movements in a wave called
Undulations
What is a transverse wave
In transverse waves the vibrations are at right angles to the direction of wave travel and move up and down. Not all transverse waves require a medium to travel through
Can water waves be reflected
Yes water waves can be reflected and change to a different direction
What is a crest in a wave
The highest point of a wave
What is a trough in a wave
The lowest point of the wave
What is displacement in a wave
How far a point on the wave is from the resting line
What is amplitude in a wave
The maximum displacement, meaning the displacement from the middle lime to the crest or trough
What is frequency in waves
The number of waves produced by a source each second. It is measured in Hertz (Hz)
What machine visualises sound waves
Oscilloscopes
What does pitch tell us
How shrill or deep something is. It is also measured in Hertz (Hz)
The pitch of a sound depends on
The frequency
What range of hertz can a human hear and what is it called
20-20,000 hertz and it is called the audible frequency range
What do you call a sound above 20,000 hertz
Ultrasound
What do you call a sound below 20 hertz
Infrasound
What is 1 Hertz (Hz) equal to
1 sound wave per second
What do you call the outer part of the ear
Pinna
How does the ear hear?
- Sound waves are collected by the earlobe/pinna
- The waves travel through the ear canal
- The waves make the ear drum vibrate
- The small bones (ossicles) amplify the vibrations and hit the cochlea
- The cochlea (an organ filled with fluid) turns these into electrical impulses
- The auditory nerve takes the electrical impulses to the brain
Why is the cochlea filled with fluid
Sound travels through liquids quicker
What is the name for objects that create light
Luminous sources
How do we see non luminous sources
Light waves reflect off the object and enters our eyes
What do opaque materials do
Produce shadows and do not transmit light
In a mirror you are…
The same distance behind the mirror as you are in front, you are the correct way up and inverted.
What type of lines does light travel in
Straight
What are angles used to show in a diagram of light reflected waves
The direction of light
What do you call the ray going in
Incident ray
What does a you call the ray that is reflected
The reflected ray
What does a normal line mean in a diagram of light waves
It is 90 degrees to the mirror
Is the incident ray equal in angle to the reflected ray
Yes
What are eye problems caused by
Genetics, age, dust, bright light, how eyes developed, infectious diseases and previous eye injuries
What are objects that do not give out light
Non luminous
Why does cleaning or smoothing a surface make it shinier
Shiny surfaces are smooth so they reflect light in a regular way to form a clear image, also known as speculative reflection. Rough or bumpy surface scatter light that falls on them which makes them look duller, also known as diffused reflection. (The diagram below shows a smoother surface but a rough surface would have the arrows scattering in different places)
\ /\
\ /
\ /
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Our eyes have … lenses and what do they do
Convex. These lenses focus the light and enable us to see
What is the point where the rays cross called
Focal point
What coloured part of the eye controls the light entering
Iris
What part of the eye has photo sensitive cells
Retina
What part of the eye changes it’s shape to focus light
(crystalline) lens
What part of the eye is a convex transparent ‘window’ that does most of the focussing
Cornea
An image formed on the eyes retina will be…
Upside down
Convex lenses focus light rays by bending them. What is the name for this bending effect
Refraction
Sources of light emit energy, which is carried by light waves until they hit an absorber. What is an absorber
Materials that absorb light and are often dark colours.
Give one example of an absorber
Aluminium foil
What is transferred when light hits an absorber
Atoms and molecules which is emitted as thermal energy
What does the cornea do
Clear area of the sclera, it refracts light - bends it as it enters the eye.
What does the iris do
Muscles which alter the size of the pupil, controlling the amount of light entering the eye.
What does the blind spot do
Where the optic nerve leaves the retina so lacks receptor cells.
What does the retina do
Contains the light receptor cells.
What does the optic nerve do
Carries impulses between the retina and the brain.
What does the sclera do
White, tough outer layer.
What does the conjunctiva do
Protects and lubricates the eye and produces mucus and tears
What does the lens do
Focuses light onto the retina.
What are receptor cells
Cells in the retina that convert light into electrical impulses
What does the pupil do
Small hole at the centre of the iris through which light enters the eye.
What does the choroid do
Pigmented middle layer with many blood vessels. It absorbs light to avoid reflection and supplies retina with nutrients to maintain temperature and volume of the eye.
What is the pupil reflex
When exposed to strong light, the pupil contracts to reduce the light entering the retina
What are the ossicles
Hammer, anvil and stirrup
When can you hear an echo
An echo is heard when a sound wave bounces off a surface and comes back into your ear
A ship off the coast is 510 m away from a cliff and blows its horn. If the people on the ship hear an echo 3 seconds later, what is the speed of the sound wave?
340 m/s because you must double 510 as it is going there and back and then divide it by 3 to know how fast it traveled in a singular second
What surfaces do and do not reflect well
Hard smooth surfaces reflect well while soft rough surfaces do not
What is a longitudinal wave
Where particles move side to side parallel to the direction of energy transfer. They require a medium to travel through
What is a wave trace
Where particles move side to side parallel to the direction of energy transfer. They require a medium to travel through
What is a wavelength
The difference between peaks on a wave trace
What happens when light enters a more dense substance
It bends more towards the normal line
Transmit meaning in light
When light moves through a new medium unaffected
What is a virtual image
An upright image where the rays seem to diverge, using a concave lens
What happens to a shadow when the object is closer to the light source
The shadow gets bigger
What do concave lenses do to rays
Causes them to bend outwards (diverging)
How do we see things
- Light enters the pupil
- The size if the pupil is altered by the iris
- The cornea and lens focus light onto the retina
- The retina contains two light sensitive cells called rods and cones. When light hits these cells, chemical reaction produce electrical impulses that travel through the optic nerve to the brain
What would happen if a guitar had a thicker string
A lower pitch
What would happen if the strings on a guitar were tightened
It would have a higher pitch
What colours do white light consist of
Red, orange, yellow, green, blue, indigo and violet
Why does refraction happen
When a waves travels at an angle (non perpendicular), a change in speed through a different medium occurs, causing it to travel at a different angle
What happens when light enters a more dense substance
It bends more towards the normal line
What is a virtual image
An upright image where the rays seem to diverge, using a concave lens
What happens to a shadow when the object je further away from the light source
The shadow gets smaller
What is the speed of light per second in meters
3,000,000 m/s
What happens when light speeds up
It bends away from the normal
What is the focal length
The distance between the lens and focal point
What do decibels measure
The loudness of a sound
What does translucent mean
Only some light can pass through
What does transparent mean
Allows light to pass through
How do we see
- Light enters the eye through the pupil
- The size of the pupil is altered by the iris
- The cornea and lens focus light onto the retina
- The retina contains two light sensitive cells called rods and cones. When light hits these cells, chemicals reactions produce electrical impulses that travel through the optic nerve to the brain
How do we see white
It absorbs no colour and reflects all colours equally
How do we see black
It’s absorbs all colours equally and reflects none
What would happen if strings were plucked harder on a guitar
It would be loud
What does the ciliary muscle do
Adjusts the shape of the lens to focus on different distances
Can sound travel in a vacuum
No
What happens to colours that are absorbed when passing through a colour filter
It does not pass through it
What do RGB filters do
Only transmits their colour and absorbs the others.
What do colour filters absorb and transmit
Colour filters transmit the colours they are made of and absorb the colours they are not
What do coloured surfaces do
Reflect their own colour but absorb the other colours
If a cyan colour filter reflect a red surface what would happen
No light would show because there is no red light to be reflected (got absorbed in the filter) and the green and blue light got absorbed on the red surface
How can you split up the different colour lights, that white light is made of and what it’s technical name for splitting up white light
Using a prism and this is also known as dispersion
What is meant by the spectrum of light
The different colours in white light
Why does the spectrum of light disperse on a prism
Different colours of light refract by different amounts
Are water waves longitudinal or transversal
Transversal
Are sound waves longitudinal or transversal
Longitudinal
What happens when two water waves meet
They either add together or cancel each other out. This change is called superposition.
What happens when two water waves are in phase
If the peaks and troughs line up with the other wave, they add together and have a higher peak/crest and a lower trough
What happens if the two water waves meet out of phase
If the first wave’s peak lines with the other wave’s trough etc, they cancel out and meet in the middle. This means that the amplitudes of the two waves subtract and create a smaller wave with an amplitude of the difference between the two. If the two waves are of equal amplitude, then they will cancel out completely.
Are light waves longitudinal or transversal
Transversal
What is the wave speed formula
v= f x l
v is the wave speed (m/s)
f is the frequency (Hz)
l is the wavelength (m)
What does and doesn’t change when a wave enters a new medium
Does change- wave speed and wavelength
Doesn’t change- frequency
When does refraction not happen, even if the speed changes in the new medium
If the wave approaches the medium at an angle perpendicular to it
What 4 things happen when waves hit a medium
Transmission, absorption, refraction and reflection
