In the context of the Doppler effect in light,the term 'red shift' signifies:

In the hydrogen spectrum,the wavelength of the ${H_\alpha}$ line is $656 \ nm$,whereas in the spectrum of a distant galaxy,the ${H_\alpha}$ line wavelength is $706 \ nm$. The estimated speed of the galaxy with respect to the Earth is:

$A$ galaxy is moving away from the Earth at a speed of $286 \, km/s$. The shift in the wavelength of a red line at $630 \, nm$ is $x \times 10^{-10} \, m$. The value of $x$,to the nearest integer,is........
[Take the value of speed of light $c$ as $3 \times 10^{8} \, m/s$]

If a source of light is moving away from a stationary observer,then the frequency of light wave appears to change because of

$A$ heavenly body is receding from Earth such that the fractional change in wavelength $\lambda$ is $1$. What is its velocity?

For an observer on the earth, if a spectral line of wavelength $6600 \, \text{Å}$ emitted by a star is found to be red shifted by $22 \, \text{Å}$, then the star is