Relevant Waves Flashcards
What happens when waves travel through a medium
The particles oscillate and transfer energy between each other but overal the particles stay in the same - only energy is transferred
What is the aplimitude of a wave
the maximum displacement of a point on a wave away from its undisturbed position.
What is the wavelength
the distance from a point on one wave to the equivalent point on the adjacent wave.
What is the frequency of a wave
The number of completed waves passing a certain point per second. Frequency is measured in herts
What is an example of a transverse wave
The ripples on a water surface or a wave of a string
Transverse waves characteristics
The oscillations (vibrations) are perpendicular to the direction of energy transfer
Longitudal wave characteristics
The oscillations are parallel to the direction of energy transfer
Examples of longitudal waves
Sound waves or shock waves
Movements of longitudal waves
They refract and compress
What is wave speed
The wave speed is the speed at which the energy is transferred (or the wave moves) through the medium.
What is the crest and trough of a wave
Top and bottom
How can waves be reflected
Waves can be reflected at the boundary between two different materials. Waves can be absorbed or transmitted at the boundary between two different materials.
Angle of incidence =
Angle of refraction
What three things can happen when waves arrive at a boundry between two different materials
- reflect
- absorb
- tansmitt (leads to refraction)
What affects how waves do when arrive at two different objects
What happens depends on the wavelength and the properties of the materials involved
What is the angle of incidence
The angle between the incoming wave and the normal
What is the angle of refraction
The angle between the reflected wave and the normal
What is the normal
a line perpendicular to the surface at the point of incidence
What is specular reflection
Happens when waves reflec a single direction by a smooth surface.
What is diffuse reflection
When a wave is reflected by a rough suface and the reflected rays are scattered as the normal is different for each incidence ray.
What affect refraction
How the wave speeds up or slows down depending on density of two materials
What happens when a wave crosses a boundry and slows down
The light will bend towards the normal (opposite for when it speeds up)
How does the waves change when refracted
The frequency stays the same but the wavelength changes
How can sound waves travel
Sound waves can travel through solids causing vibrations in the solid.
How do sounds waves get heard by humans
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.
Why can sound only work over limited frequency range and the relevance of this to human hearing.
Different materials can convert different frequencies of sound waves into vibrations. (Humans can only hear 20Hz - 20kHz). Humans hearing is limited by the size and shape of our ear drum, as well as the structure of all parts within the ear that vibrate to transfer energy from sound waves.
When will sound waves refract
As they enter denser material and speed up as the waves travel into a different medium.
How can sound waves be used for ultrasound
Ultrasound waves have a frequency higher than the upper limit of hearing for humans. (20,000Hz) 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.
How can uktrasound be used
Medical imaging: be used to detect the boundry of fluid in womb and foetus, with some waves being reflected back.
Industrial imaging: crack in materias can be detected by waves reflecting out of them
How can waves be used to detect or explore
Waves can be completely reflected or partically. The wave may continue travelling in the same direction but at different speeds, or may be refracted. Strudying these path and properties can help show properties of structures that you can’t see.
How are seismic waves produced
Seismic waves are produced by earthquakes
P-waves
P-waves are longitudinal, seismic waves. P-waves travel at different speeds through solids and liquids.
S-waves
S-waves are transverse, seismic waves. S-waves cannot travel through a liquid.
What can measuring P/S-waves do
P-waves and S-waves provide evidence for the structure and size of the Earth’s core.
Echo sounding
Echo sounding, using high frequency sound waves is used to detect objects in deep water and measure water depth.
