Question

is only the wavelength can determine re and blue shift? could we have another option?

Answer 1

The other option is no shift. Red and blue shift don't mean the light ends up either red or blue, it means its frequency has shifted towards the red end of the spectrum or towards the blue end

Answer 2

Perhaps you are asking if the shift can be detected only in wavelength... if so, the answer is no, you can also detect it as a frequency shift... but wavelength and frequency are related through\[c = \lambda f\]

Answer 3

thnx stan