Given data:
fs: frequency of source (comet); fs = ?
fo: frequency observed; fo = 633*10^14 Hz
vs: velocity of source (comet); vs = 286000 m/s
vo: velocity of observer; vo = 0 m/s
c: speed of light; c = 3*10^8 m/s
Doppler effect equation:
fo/fs = (c + vo)/(c + vs)
633*10^14/fs = (3*10^8)/(3*10^8 + 286000)
Solving for fs,
633*10^14 = fs*(3*10^8)/(3*10^8 + 286000)
(633*10^14)(3*10^8 + 286000)/(3*10^8) = fs
fs = 633.6*10^14 Hz, which is the true frequency of light the source emits
Answer: 633.6*10^14 Hz
