P12 Flashcards
How do waves transfer energy?
The way they are travelling
What happens when eaves travel through a medium?
The particles of the medium oscillate and transfer energy between each other.
Whats the amplitude of a wave?
Maximum displacement of a point on the wave from it’s undisturbed position
Where is the amplitude?
Middle line to the top of the wave
What is the wavelength?
The distance between the trough of one wave to the trough next to it
Whats the frequency?
The number of complete waves passing a certain point per second
What is frequency measured in?
Hz
How to find the period (s)?
1/f
What are all waves either?
Transverse or longitudinal
What are transverse waves?
Where the oscilations are perpindicular to the direction of energy transferr
What waves are transverse?
- All EM waves
- A wave on a string
- All ripples and waves in water
What vibrations do transverse waves have?
Sideway
What vibrations do longitudinal waves have?
Parallel
What are longitudinal waves?
The oscilations are parallel to the direction of energy transfer
Examples pf longitudinal waves?
Sound waves and shock waves
Wave speed =
Frequency x wavelength
Whats the wave speed?
Speed energy is being transfered
What are sound waves caused by?
Vibrating objects
What type of wave is sound?
Longitudinal
What does sound travel faster in?
Solids than liquids
But liquids than gas
What happens whn a sound wave travels a solid?s
It causes particles in the solid to vibrate
Why cant sound travel is space?
Its mostly a vaccum and there are no particles to move or vibrate
When do you hear sound?
When your eardrums vibrate
What are the steps from sound to your ear?
1) Sound waves reach your ear
2) The vibrations reach a tiny bone in your ear called ossicles
3) The cochlea turns the vibrations into electrical signals which get sent to your brain and allows you to hear
What are the ranges humans can hear ?
20hz - 20khz
Why is human hearing limited?
Due to the size and shape of your ear
What can sound waves do?
Reflect or refract
How are sound waves reflected?
By hard flat surfaces
What are echoes?
Reflected sound waves
What happens when sound waves go into another medium?
They speed up
Why do soundwaves speed up?
They travel to another medium so its wavelength changes but frequency stays the same so speed changes
Whats an ultrasound?
Is sound with frequencies above 20,000Hz
What happens at boundaries?
Ultrasound waves get partially reflected
What is partial reflection?
When some of the wave is reflected between the two mediums and the other is refracted
How do you messure how far the boundary is?
The time it takes for the reflections to reach a detector
What are ways ultrasound is useful?
- Medical imageing
- Industrial imaging
How can you figure out the earths inner structure?
Use seismic waves
What causes seismic waves?
Earthquakes and explosions
What do seismologists do?
Work out the time it takes for the shockwaves to reach the seismometer also which part doesnt reach shock waves at all
What travels through the earths core?
P-Waves
Things about p waves?
- They are longitudinal
- They travel through solids and liquids
- They travel faster than s waves
Things about s-waves?
- Cant travel through liquids or gases and are transverse.
- Slower than P - waves
