$A$ star is moving away from the Earth. An observer on the Earth will see the wavelength of light coming from the star as:

An observer is moving with half the speed of light towards a stationary microwave source emitting waves at frequency $10 \ GHz$. What is the frequency of the microwave measured by the observer? (Speed of light $c = 3 \times 10^8 \ ms^{-1}$)

$A$ rocket is moving away from the earth at a speed of $6 \times 10^7 \ m/s$. The rocket has blue light in it. What will be the wavelength of light recorded by an observer on the earth in $\mathring A$? (Wavelength of blue light $\lambda = 4600 \ \mathring A$)

Due to the Doppler effect, the shift in wavelength observed is $0.1 \text{ Å}$ for a star producing a wavelength of $6000 \text{ Å}$. The velocity of recession of the star will be: (in $\text{ km/s}$)

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:

The wavelength of light observed on the earth,from a moving star is found to decrease by $0.05\%$. Relative to the earth,the star is: