Waves Flashcards
what are transverse waves?
oscillations perpendicular to direction of energy transfer
longitudinal waves?
oscillations parallel to energy transfer direction
what are the compressed and stretched regions of a longitudinal wave called?
compressed - compression
stretched - rarefaction
what is the law of reflection?
angle of incidence = angle of reflection
when does refraction occur?
when a wave enters a different medium which causes a change in direction and speed unless its 90 degrees
which sunlight colour travels fastest in water and is refracted the least?
red
what is the doppler effect?
closer something it is
shorter wavelength therefore higher freq.
so we hear different frequencies depending on distance from source
How is a sound wave heard in the brain?
vibrating source causes surrounding medium to vibrate
pattern of vibrations travels into eardrums which is forced to vibrate at same frequency
these vibrations send an electrical signal to the brain
what happens to sound wave travel when there is no air?
no vibrations are passed on
which medium does sound waves travel fastest?
solids
easier to pass on vibrations
what do sound waves obey?
law of reflection
angle of incidence = angle of reflection
how are echos heard?
reflection of sound waves from one or more surfaces
how do sonar or ultrasound work?
sound waves reflect
measured d = velocity *time times 2 there and back
how is ultrasound used?
depth detection in sonar , medical non invasive imaging?
how is ultrasound used in non invasive medical imaging?
can detect boundary between different tissue types
some ultrasound reflected
time taken shows depth and tissue type
which can be used to produce image of soft tissue in body
what are the different electromagnetic spectrum waves?
radiowaves
microwaves
infrared
visible light
ultraviolet
xray
gamma
what happens in the EM spectrum as wavelength decreases?
frequency decreases
Gamma - shortest wavelength
what are the EM waves used for?
radiowaves - communication radio TV
microwaves - communication ; pass through water for cooking
infrared - heat cameras; causes greenhouse effect
visible light - optical fibres and in pictures
UV -can cause skin cancer - ionising radiation
xray - medical imaging
gamma - sterilising,cancer,radiotherapy – very ionising
Which EM wave is the most ionising but the shortest wavelength?
Gamma shortest wavelength
highest freq
