P12 - Reflection/ Refraction Flashcards
3 effects of a wave at a boundary
-reflection
transmission
-refraction
ripple tanks
-used to study waves in controlled conditions
-makes plane waves by moving a straight edge along the water surface
-waves will move at same speed/distance
plane waves
straight waves
speed of waves -
distance travelled by each wave every second through a medium
-speed of energy transfer
wave speed formula
frequency x wavelength
speed of sound formula
distance/time
normal of surface
90 degrees to surface
refraction
change of direction of wave when they cross a boundary between mediums
Refraction: non zero angled wave to boundary
change speed + direction
Refraction: normal incident ray
speed changes only
wave front
line from crest to trough
diff between refracted and incident waves
-same frequency
-diff speeds so diff wavelengths
Refraction: more dense medium
-refracted ray will be towards normal (smaller angle )
Refraction: less dense medium
-refracted ray will be away from normal (larger angle )
Law of reflection
angle of incidence = angle of reflection
partial reflection
-waves directed at a substance may be reflected and some may be transmitted/absorbed
-depends on surface/wavelength
waves that are absorbed by waves
some waves are absorbed by substance
-heats surface = energy gain
amplitude in absorption
as waves travel through
-amplitude decreases
-as more energy is absorbed
transmission
-waves that aren’t absorbed are allowed to pass through
reflection in a ripple tank
-plane waves are reflected from a straight barrier at same angle as incident waves
-speed/ wavelength won’t change
does reflection of a wave alter speed or wavelength
no
-no change in medium
-reflected into original medium
