Topic 4 - Waves Flashcards
transverse waves
the mediums particles vibrate energy in a right angle to the direction of motion
longitudinal wave
the mediums particles vibrate energy in the same direction of the motion
mechanical waves
transfer of energy through a medium
electromagnetic waves - type of wave
transverse waves that do not need a medium through which to travel
wave frequency (Hz)
the number of waves passing a point each second
period
the length of time it takes one wave to pass a given point
wavelength of a wave (m)
the distance from a point on one wave to point in the same position on the next wave
amplitude of a wave (m)
from the middle of the wave to the top or bottom
velocity of a wave
the speed of the wave in the direction it is travelling
velocity of a wave equation
velocity = frequency x wavelength
wavespeed equation
wave speed = frequency x wavelength
(m/s) (Hz) (m)
what can change the speed of a wave
the medium through which is it travelling
refraction
when a wave travel from one medium through to another medium at an angle causing it to bend; this is caused by the wave changing speed as it passes through different mediums
what’s happening to the speed of a wave if it bends towards the normal line
it’s slowing down
what’s happening to the speed of a wave if it bends away from the normal line
it speeds up
what controls how much light is bent
the greater the difference in speed between the two media’s
—> great difference = more light bent
the normal line
the line that’s at a right angle to the interface
the interface
the boundary between two media
wave can be reflected
wave ‘bounces’ off the boundary
waves can be refracted
the wave passes into the new material, but changes the direction in which is travelling (wave bends at the boundary)
waves can be transmitted
the wave passes through the material and is not absorb or reflected
waves can be absorbed
the wave disappears as the energy is carrying is transferred to the material (the wave is dispersed at the boundary)
white light
made up of a mixture of different frequencies - we see these different frequencies as different colours
why do we hear different pitches of sounds
because of different frequencies of sound
what changes when a sound enters a different material
the wavelength and the velocity, NOT the frequency
what type of waves are sound waves
longitudinal
process to hear sound
1) sound waves enter the air canal
2) the eardrum is a thin membrane; sound waves make it vibrate
3) vibrations are passed on to tiny bones which amplify the vibrations (make them bigger)
4) vibrations are passed onto the liquid inside the cochlea
5) tiny inside the cochlea detect these vibrations and create electrical signals called impulses
6) impulses travel along neurons in the auditory nerve to the brain
when a wave hits a boundary, what can it do
- be reflected
- be refracted
- be transmitted
- be absorbed
ultrasound
waves with frequencies too high to be heard by humans (above 20kHz)
how can ultrasounds be used
- animals to communicate or navigate
- sonar equipment to find the depth of the sea or detect fish
- ultrasound scan to make images inside the body
how does an ultrasound scan work
The ultrasound machine detect the time between sending the pulse out and receiving the echo
infrasound
waves with frequencies too low to be heard by humans (below 20kHz)
seismic waves
infrasound waves that are produced by earthquakes
how are seismic waves detected
seismometer
what types of seismic waves are there
longitudinal P waves or transverse S waves
what type of waves are P waves
longitudinal
what type of waves are S waves
transverse
what type of states of matter can longitudinal waves transmit through
solids, liquids, gases
what type of states of matter can transverse waves transmit through
only solids
S wave shadow zone
the zone of the Earth on the opposite side to the earthquake
why does the S wave shadow zone occur
because part of the earths interior is liquid so the waves can’t pass through it so underneath this liquid core, it’s a shadow zone
for light what does the frequency determine?
colour
- higher frequencies means blue colours
- lower frequencies means red colours
The sound what does frequency determine?
pitch
- a high frequency results in a high pitch
- a low frequency results in a low pitch
What happens with light when amplitude changes
- Higher amplitude results in an increase of light
- Low amplitude results in a decrease of light
how do we work out the speed of waves on water?
Measure the time it takes for a wave to travel between two fixed points
How do you work up the speed of sound?
Measure the time it takes for a sound to travel a certain distance, for example, measure the time it takes for an echo of a loud sound to reach you
what happens when waves on the surface of water when they cross an interface from shallow water into deep water?
- They speed up
what happens when waves on the surface of water when they cross an interface from deep water into water water?
- they slow down
what happens when waves on the surface of water when they cross an interface from deep water into water water?
- they slow down
explain the process of how the internal structure of a human air lets the brain hear sound
- Sound waves enter the ear canal.
- The eardrum is a thin membrane sound waves make it vibrate.
- Vibrations apart from a tiny bones which amplify the vibrations (make them bigger)
- Vibrations are passed onto the liquid inside the cochlear.
- Tiny hairs inside the cochlear detect these vibrations and create electrical signals called impulses.
- Impulses travel along neurons in the auditory nerve to reach the brain.
what part of the cochlear detects high frequencies?
base
Which part of the cochlea detects low frequencies?
apex
Function of the hair cells in a cochlear
Detects vibrations - each cell is connected to a neurone that sends impulses to the brain
function of the fluid inside a cochlea
fluid transmit sound waves
