I came across this equation on Wikipedia:
$$z=\frac{\lambda_{\text{observed}} – \lambda_{\text{emitted}}}{\lambda_{\text{emitted}}}$$
and it got me thinking: If I measure a wavelength of $700 \;\text{nm}$ compared to a rest wavelength of $656 \;\text{nm}$, that gives me a redshift of $0.097$.
So if every wavelength gets shifted by the same amount, in this case $720 – 656 = 64 \;\text{nm}$. Does that mean that the redshift value is different for every wavelength?
If not, every wavelength gets shifted by a different amount with a fixed redshift value?
How you calculate the velocity of a body in these scenarios?
Best Answer
Every wavelength doesn't get redshifted by the same absolute amount.
Every wavelength is multiplied by a factor of $1+z$.