P7: General Properties of Waves Flashcards
What do waves do?
Transfer energy without transferring matter.
Mechanical waves
A vibration that travels through a substance.
Longitudinal waves
Waves in which the vibrations are parallel to the direction of energy transfer.
Transverse waves
Waves in which the vibrations are perpendicular to the direction of energy transfer.
Electromagnetic waves
Can travel through a vacuum, no medium is needed.
Examples of mechanical waves
sound, water, seismic
Examples of electromagnetic waves
light, radio, micro
Examples of Transverse waves
All electromagnetic waves
Example of longitudinal waves
Sound
Amplitude
Height of the wave crest.
The bigger the amplitude of the waves…
…. the more energy the waves carry.
Wavelength
The distance from one wavelength to the next.
Frequency
The number of wave crests passing a fixed point every second.
Speed of waves
Distance travelled by a wave crest every second.
Wave speed (m/s) =
Frequency (Hz) x Wavelength (m)
Straight waves
Plane waves
Reflection
The change of direction in a light ray or wave at a boundary when a wave/ray stays in the incident medium.
Refraction
The change of direction of a light ray when it crosses a boundary between two transparent substances.
Diffraction
The spreading of waves when they pass through a gap or around the edges of an obstacle.
The smaller the hole…
… The greater the diffraction
When is diffraction most noticeable?
When the hole is the same size as the wavelength of the wave.
What can diffraction cause?
Bad TV and Radio connection
Interference
Reinforcement or cancellation of waves when two sets of identical waves overlap.
When waves overlap crest to crest…
… constructive interference/ reinforcement takes place
What waves overlap crest to trough…
… destructive interference/ cancellation takes place.
