doppler effect Flashcards
What happens when a source of sound waves moves relative to a stationary observer
the observed frequency is different from the source frequency
What expression should you use for the observed frequency when a source of sound waves moves relative to a stationary observer
fο = fs v / (v ± vs)
Frequency of waves observed by stationary observer = frequency of waves emitted by the source x speed of waves through the medium / (speed of waves through the medium +- speed of the source of waves)
what is doppler shift
Doppler shift is the apparent change in frequency (and wavelength) of a wave when there is relative motion between the source of waves and an observer
v =
Speed of waves through the medium
vs =
Speed of the source of waves
fs =
Frequency of waves emitted by the source
f0 =
Frequency of waves observed by the stationary observer
When should you use + or - symbol for the expression
fο = fs v / (v ± vs)
if f0 > fs use -
If f0 < fs use +
what is blueshift
When lightwaves move towards you causing the light to turn blue, red shift is the opposite
doppler effect siren example
A police car
What does λ stand for?
wavelength of compressed waves in front of moving source
What speed does source move at speed
Source moves at speed vs m s-1 and emits fs waves per second
In distance (v – vs) metres, how many waves are there
In distance (v – vs) metres, there are fs waves
