Waves GapFill

Waves are the repeated motion of particles (or fields) around a point, that carry energy from one place to another.
Frequency (f) and period (T) of waves are related by the equation  f = 1/T²f = T/2f = 1/Tf = T².
Wave speed (v), frequency (f) and wavelength (λ) are related by the equation  v = f/λv = f²λv = fλ²v = fλ.

When a wave meets a boundary between two materials, it can be absorbed, transmitted or reflected. Whether a wave is absorbed, transmitted or reflected can vary with  the wave speedthe materials comprising the boundaryits speed in airits wavelength and the materials comprising the boundary and the angle of incidence.  A reflected wave  stops travelling once it reaches the boundarydoes not pass through the boundary, and instead travels back into the medium it was originally inpasses through the boundary unchangedchanges direction after passing through the boundary.

The frequency generally remains unchanged when waves are reflected or transmitted. Where waves are transmitted at a boundary, the speed at which the wave can travel will be different in different mediums. If the wave speed changes but the frequency remains the same, the  periodwaveamplitudewavelength will be different in the new medium. This usually results in a change of  amplitudemagnitudedirectionrefraction of the wave. This change of direction is known as  transmissionreflectionrefractiondiffraction.

Sound waves travel as vibrations in the air. Within the ear, this causes  the eardrum to become chargedthe brain to vibratethe eardrum to vibratethe whole ear to vibrate, which is converted into a signal which can be interpreted by the brain. Humans can only hear sound waves within a frequency range of around 20 Hz to 20 kHz; frequencies above 20 kHz are known as  supersoundinfrasoundultrasoundhypersound and this is used in medical and industrial imaging processes. Sound waves with frequencies below 20 hertz, Hz, are known as  supersoundinfrasoundhypersoundultrasound.
Earthquakes produce  geographic wavesterrestrial wavesseismic wavesmagma waves, which travel through Earth's crust and mantle, and, when detected, can tell us information about where the earthquake originated and the composition of Earth.
Imaging techniques using sound measure  the intensity of the wavethe change in frequency of the wavethe wavelength of the wavethe time taken between a wave being emitted and detected to determine the distance to the reflecting object or surface