Apparent wavelength of light coming from a star moving away from Earth is $0.02 \%$ more than its actual wavelength. The velocity of the star is ........ $km/s$.

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:

If the velocity of a galaxy relative to the Earth is $1.2 \times 10^6 \, m/s$,then the percentage increase in the wavelength of light from the galaxy as compared to a similar source on Earth will be ...............$\%$

The Doppler effect in sound,in addition to the relative velocity between the source and the observer,also depends on the individual motion of the source and the observer relative to the medium. However,the Doppler effect in light depends only on the relative velocity between the source and the observer. The reason for this is:

With what speed should a galaxy move outward with respect to Earth so that the sodium-$D$ line at wavelength $5890 \ \mathring{A}$ is observed at $5896 \ \mathring{A}$? (in $\text{km/s}$)

The apparent wavelength of the light from a star moving away from the Earth is $0.01\%$ more than its real wavelength. Then the velocity of the star is......$km/sec$.