C5 Doppler Effect

Doppler

C5.1 Doppler effect

When source of sounds moves away from an observer, it sounds lower in pitch; decreased f; increased λ. But its relative as in reality its still same f. When both stat. , same f. Moving relative; diff frequency

←source - O: decreased f, increased λ: red shift

→source - O: increased f, decreased λ: blue shift

C5.2 Δλ

λ + Δλ = away
λ - Δλ = towards

C5.3 Doppler in light

^Δf/_f = ^Δλ/_λ = ^Δv/_c (Δv = relative velocity source/observer)

Δv = v_source - v_observer

Δλ = λ_observed - λ

C5.4 Galactic Redshift

Redshift: object away from earth: λ increases
Blueshift: object towards earth: λ decreases
Universe is expanding.

C5.5 Equations for doppler effect of sound

f’_(observer) = f_{(source freq)} (^v / _{^{v ± u}s})
source to obs: v-u
source away obs: v+u
v_sounds = 340 ms^-1
u_s = speed of moving source relative to observer

f’_(obs) = f_{(source freq)} (^{v ± u_o} /_v)
obs to source: v+u
obs away source: v-u