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## Homework Statement

A distant galaxy moving away from us at speed 1.85 *10^7 m/s. Calculate the fractional redshift (lambda'-lambda(0))/(lambda(0)) of the light from this galaxy.

## Homework Equations

(lambda'-lambda(0))/(lambda(0))=lambda'/lambda(0)-1;

f=(sqrt(1-beta)/sqrt(1+beta))*f(0)

f/f(0)=lambda/(lambda(0))

## The Attempt at a Solution

lambda(0))/lambda=f/f(0)= sqrt((1-beta)/(1+beta))=.980 since the galaxy is receding.

(lambda-lambda(0))/lambda(0)=(lambda/lambda(0))-1

1/(f/f(0)) = lambda/(lambda(0))=1.0204

therefore the fractional redshift is :

(lambda-lambda(0))/(lambda(0)=(lambda/lambda(0))-1= 1.0204-1=.0204