(adsbygoogle = window.adsbygoogle || []).push({}); A distant galaxy is moving away from us at a speed of 1.85x10^7m/s. Starting from the formula for the doppler shifted frequency, derive a formula for the change in wavelength and hence calculate the fractional redshift (λ'-λ₀)/λ₀ in the light from the galaxy.

I'm pretty confused at the moment as i've seen the formula i need written in two different ways:

f₀ =f [tex]\sqrt{}[(1+v/c)/(1-v/c)][/tex]

and

f₀ =f [tex]\sqrt{}[(c+v)/(c-v)][/tex]

Are these two different forms of the same equation, as I can't seen to derive one from the other?

I suppose then the relationship I need to use is v = f λ, but im confused about which values of velocity, wavelength etc this equation relies on in this instance.

Sorry if i've missed something obvious as I don't think this question should be too hard, but I just can't think where to start.

Thanks for any help

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# Homework Help: Relativistic Doppler shift Problem

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