SP4 Waves Flashcards
How do transverse waves move
Perpendicular to the direction
How do longitudinal waves move
Parallel to the direction
What is frequency
Wave frequency is the number of waves that pass a certain point each second
What is frequency measured in
Hz
What is the period
The length of time it takes one wave to pass a given point
What is the wavelength
The distance between a point on one wave and a point in the same position on the next wave
What is the amplitude
The maximum distance of a point on the wave away from its rest position
The greater the amplitude the louder the sound
What waves are transverse
Waves on the surface of water
What waves are longitudinal
Sound waves
What is the velocity
The speed of the wave in the direction it is travelling
Waves travel at different speeds in different materials
How do you calculate the speed of a wave
speed = distance / time
speed = frequency × wavelength
What is refraction
The change in direction of light across different materials
Where does refraction happen
The interface
Does light travel faster or slower in air than it does in glass or water
Faster
How does the bend in refraction differ
The greater the difference in speed between the two media the more the light is bent
The light bends towards the normal when it slows down
What happens when a wave is reflected
It bounces off the material
What happens when a wave is refracted
The wave passes into the material but changes the direction in which it is travelling
What happens when a wave is transmitted
The wave passes through the material and is not absorbed or reflected
What happens when a wave is absorbed
The wave disappears as the energy it is carrying is transferred to the material
How do our ears pick up sound
The eardrum is a thin membrane which vibrates
Vibrations are passed onto tiny bones which amplify the vibrations
The vibrations are passed onto the liquid inside the cochlea
Tiny hairs inside the cochlea detect these vibrations and create electrical signals called impulses
Impulses travel along neurons in the auditory nerve to reach the brain
What is the cochlea
A couled tube inside our ear containing a liquid. It can detect the different frequencies of sound reaching the ear.
What range of frequencies can be heard by humans
20Hz to 20000Hz
What regions of the cochlea pick up which frequencies
The base (where it is thicker) picks up higher frequency sounds and the apex (where it is thinner) picks up lower frequency sounds
Why is it important that different parts of the membrane in the cochlea have different stiffness
Different thicknesses of the membrane vibrate best at certain frequencies
What is ultrasound
Humans can detect sounds up to 20000Hz so waves with higher frequencies than this are called ultrasound
When is ultrasound used
Some animals use ultrasound to communicate with eachother and some animals use it to detect objects around them with it
What are ultrasound scans and when do we use them
Ultrasound can be used to make images of things inside the body for example a scan of a developing fetus in the womb. We use them to see how well the fetus is developing.
What is sonar equipment
Sonar equipment on boats is used to detect the depth of water. It sends waves of sound to the sea bed and waits for the waves to be reflected and picked up by the microphone beneath the boat
How can sonar be used to detect depth
Depth = (distance = speed ÷ time) ÷2
What is infrasound
Humans can hear frequencies of 20Hz-20000Hz so sounds below 20Hz are infrasound
