P5.1 Flashcards
What is a wave
A wave is an oscillation that transfers energy.
What are mechanical waves
Mechanical waves such as sound and water waves need a (matter) medium to travel through whereas electromagnetic waves don’t.
What is longitudinal wave
The direction of the travel of the wave is the same as the direction of vibration of air molecules
What is a transverse wave
Transverse waves the direction of the vibrations are at right angles to the direction of the wave travel (water waves). The energy transfer is in the direction of the wave
What is amplitude
Distance from the middle to the top or bottom of wave
What is wavelength
Distance from one point on the wave to the same point on the next wave
What is frequency
Number of waves or oscillations per second (Hz)
What is time period
Time for a wave to pass a given point
What does a time trace show
It shows how displacement varies with time at a particular position.
A snapshot
A snapshot shows how displacement varies with distance
What is the formula for wave velocity
Wave velocity = frequency x wave length
Frequency formula
1/t
How can you measure wave velocity
You can measure the velocity of a wave ripple tank. You can measure the wavelength using a ruler and flashing strobe and calculating the number of rotations per minute for the frequency. You then put it in the formula to work out wave speed.
Another way to measure wave velocity
Echoes
Last way to measure wave velocity
You can also connect a pair of microphones a certain distance apart to an oscilloscope.
What happens when a wave travels to one medium from another
Its velocity can change and so can its direction. This is refraction.
When a sound wave becomes quicker what happens
The direction of the sound wave moves away from the line at 90 degrees to the surface called the normal.
When a sound wave speeds up what happens
It’s frequency stays the same, the wave speed increases the wave length increases
What happens when a sound wave meets a boundary
Be reflected
Be transmitted
Be absorbed
What is ultrasound
Ultrasound is a sound with a frequency greater than 20,000. And it can be focused into a beam.
What is ultrasound used for
Ultrasound is used to image soft tissue.
The transmitter beams ultrasound into the mother. The waves can reflect of the different boundaries. The machine calculates the distances using time and velocity and uses those distances to produce an image. You can use this to find depths.
What can u use to work out depth
You can use echoes and sonar to calculate depths
What happens when sound hits a solid
When a sound hits a solid some a solid particles vibrate and the wall gets a bit hotter
What is your ear designed to do
Your ear is designed to detect, amplify and convert sound to an electrical signal
What does the outer ear do
The outer ear (pinna and auditory canal) gathers the sound wave and directs it to the eardrum which vibrates.
What does the eardrum do
As the ear drum vibrates it makes the ossicle vibrate which amplify the vibration and pass it on to the inner ear through the oval window.
What does the cochlea do
The cochlea is shaped like a snail shell and contains fluid which transmits the movement of the oval window to small hairs on the inside wall of the cochlea. It then sends a signal to the auditory nerves to your brain.
What is a natural frequency
If you apply a vibration to them at their natural frequency they will vibrate with a very big amplitude.
What do the hairs inside the cochlea do
Vibrate at different frquencies. The range of frequencies that you can hear depends on the range of lengths of hair in your year.
What happens as you get older
As you get older your loose your short hairs. Leading to increased difficulty to hear high frequency sounds.
Frequency formula
frequency = waves/time
