# The Andromeda galaxy is moving toward us at 3.01x105 m/s. By how much will the frequency of the 6.17x1014 Hz hydrogen?

The Andromeda galaxy is moving toward us

at 3.01x105 m/s. By how much will the

frequency of the 6.17x1014 Hz hydrogen line

be shifted in the galaxy's spectrum

Update:

3.01 × 10^5 and 6.17 × 10^14

### 1 Answer

Relevance

- NCSLv 71 year agoFavorite Answer
For a stationary receiver (observer),

new frequency f = F₀*c/(c + v) ← v -ve if src moving toward rcvr

using c = 299 792 458 m/s,

new f = 6.17e14Hz * 299792458m/s / (299792458m/s - 3.01e5m/s)

new f = 617620107836264.23161624863437674 Hz

and so the shift is

Δf = f - F₀ = 6.2010783626423161624863437674406e+11 Hz ≈ 6.20e11 Hz

Note that you get the same answer if you use c = 3e8 m/s,

Hope this helps!

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