4.6.1 Waves In Air, Fluids And Solids Flashcards
Waves are what ?
Either transverse or longitudinal
Example of a transverse wave
The ripples on a water surface are an example of a transverse wave
What do longitudinal waves show ?
They show areas of compression and rare faction
Example of a longitudinal wave
Sound waves travelling through air are longitudinal
Describe evidence that the wave itself moves?
For both ripples on a water surface and sound waves in air, it’s the wave and NOT the water or air itself that travels
Describe wave motion in terms of their amplitude, wavelength, frequency and period?
The oscillations are either parallel in longitudinal waves or perpendicular in transverse waves
What is the amplitude of a wave ?
The maximum displacement of a point on a wave away from, it’s undisturbed position
What is the wavelength of a wave?
The wavelength of a wave is the distance from a point on one wave to the equivalent point on the adjacent wave
What is the frequency of a wave?
The frequency of a wave is the number of waves passing a point every second
Period equation
Period = 1/frequency
Period units
Period, t, in seconds, s
Frequency units
Frequency, f, in hertz, Hz
What is the wave speeds
The wave speed is the speed at which the energy is transferred ( or the wave moves) through the medium.
Wave equation
Wave speed = frequency x wavelength
Wave speed units
Wave speed, v, in metres per second, m/s
Frequency units
Frequency, f, in hertz, Hz
Wavelength units
Wavelength, alpha, in metres, m
How to measure distance travelled
Use a ruler to measure the distance and then a stop watch to measure the time.
Distance / time
Show how changes in velocity, frequency and wavelength, in transmission of sound waves from one medium to another, are inter- related
the wavelength of the sound wave decreases. the frequency of the sound wave stays the same. the velocity of the sound wave decreases (since wave speed = frequency × wavelength)
How can waves be reflected?
At the boundary between two different materials
How can waves be absorbed or transmitted?
At the boundary between two different materials
show a ray diagram showing refraction at the boundary between air and glass
How does transmission reflection and absorption affect waves?
When a light wave with a single frequency strikes an object, a number of things could happen. The light wave could be absorbed by the object, in which case its energy is converted to heat. The light wave could be reflected by the object. And the light wave could be transmitted by the object.
what do soundwaves do when travelling through solids?
cause vibrations in the solid
what do soundwaves do within the ear?
sound waves cause the ear drum and other parts to vibrate which causes the sensation of sound. The conversion of sound waves to vibrations of solids works over a limited frequency range. This restricts the limits of human hearing.
Describe the processes which convert wave disturbances between sound waves and vibrations in solids
Sound waves can travel through solids causing vibrations in the solid. Within the ear, sound waves cause the ear drum and other parts to vibrate which causes the sensation of sound. The conversion of sound waves to vibrations of solids works over a limited frequency range.
describe the effect of sound waves on the ear drum
The eardrum vibrations caused by sound waves move the chain of tiny bones in the middle ear transferring the sound vibrations into the cochlea of the inner ear.
explain why such processes only work over a limited frequency range and the relevance of this to human hearing
The human ear is capable of hearing sounds with frequencies between 20-20,000HZ
Because sound waves are caused by vibrating particles, the denser the medium, the faster the sound travels. Meaning you can’t hear sound in a vacuum are there are no particles.
Sound generally travels faster in solids than liquids or gases because solids are the most dense.
what is the range of normal human hearing?
20 Hz to 20 kHz
describe how the differences in velocity, absorption and reflection between different types of wave in solids and liquids can be used both for detection and exploration of structures which are hidden from direct observation.
Ultrasound waves have a frequency higher than the upper limit of hearing for humans. Ultrasound waves are partially reflected when they meet a boundary between two different media. The time taken for the reflections to reach a detector can be used to determine how far away such a boundary is. This allows ultrasound waves to be used for both medical and industrial imaging.
Seismic waves are produced by earthquakes. P-waves are longitudinal, seismic waves. P-waves travel at different speeds through solids and liquids. S-waves are transverse, seismic waves. S-waves cannot travel through a liquid. P-waves and S-waves provide evidence for the structure and size of the Earth’s core.
Echo sounding, using high frequency sound waves is used to detect objects in deep water and measure water depth.
what did the study of seismic waves provide?
new evidence that led to discoveries about parts of the Earth which are not directly observable.
