waves Flashcards
What is a transverse wave?
In transverse waves, the oscillations (vibrations) are perpendicular to the direction of energy transfer.
What is a longitudinal wave?
In longitudinal waves, the oscillations (vibrations) are parallel to the direction of energy transfer.
What is the amplitude of a wave?
The amplitude is the height of a wave.
on a graph, from centre line to crest
What is the wavelength?
The wavelength is the length of one complete wave cycle.
What is the crest of a wave?
The crest is the top of a wave.
What is the trough of a wave?
The trough is the bottom of a wave.
What is the frequency of a wave?
The frequency is the number of waves that pass one point each second.
What is the period of a wave?
The period is the time it takes for one wave to pass a point.
What is the wave speed?
Wave speed is the speed at which energy is transferred through a medium.
How do you calculate wave speed?
wave speed (m/s) = frequency (Hz) x wavelength (m)
What three things could happen to a wave at a boundary between two materials?
Waves can either be reflected, absorbed or transmitted at a boundary between two materials.
What is the normal?
The normal is perpendicular to the boundary which reflects, absorbs or transmits the wave.
What is the angle of incidence?
The angle of incidence is the angle between the incoming ray and the normal.
This is numerically equivalent to the angle of reflection.
What is the angle of reflection?
The angle of reflection is the angle between the normal and the reflected ray.
This is numerically equivalent to the angle of incidence.
What is diffuse reflection?
diffuse reflection:
- reflection of light off of a rough surface
- the normal is different for each position on the material, so the angles of incidence and reflection are different at each position
- there is not a clear reflection
What is specular reflection?
specular reflection:
- reflection of light off of a smooth surface
- the normal is always the same
- clear reflection
What is refraction?
Refraction is when a wave changes direction at a boundary between two materials.
What affects the level of refraction for a wave?
How much a wave is refracted depends on how much the wave speeds up or slows down, which usually depends on the density of the material. The higher the density, the slower the wave travels.
What happens if a wave hits a boundary along the normal?
If a wave hits a boundary along the normal, the wave is not refracted and continues in that direction.
What is the optical density?
The optical density of a material is how quickly light can travel through it. The more optically dense an object is, the more the refracted ray bends towards the normal.
Are sound waves longitudinal or transverse?
Sound waves are longitudinal. They cause the particles to vibrate back and forth.
How do sound waves travel through a solid?
Sound waves can travel through solids by causing vibrations in the solid. This only works over a limited frequency range.
How do sound waves cause humans to hear sound?
Within the ear, sound waves cause the ear drum and other parts to vibrate, which causes sound.
What is the restriction of typical human hearing?
The typical restriction of human hearing is 20Hz - 20,000Hz (20kHz)