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

$A$ star moves away from Earth at a speed of $0.8 c$ while emitting light of frequency $6 \times 10^{14} \text{ Hz}$. What frequency will be observed on the Earth (in units of $10^{14} \text{ Hz}$)? ($c$ is the speed of light)

If the shift of wavelength of light emitted by a star is towards the violet end of the spectrum,then this shows that the star is

$A$ star emitting radiation at a wavelength of $5000 \; \mathring{A}$ is approaching Earth with a velocity of $1.5 \times 10^6 \; m/s$. The change in wavelength of the radiation as received on Earth is ....... $\mathring{A}$.

What is the Doppler effect for light? Derive the formula for the Doppler shift.

The wavelength of light coming from a star is observed to increase by $0.4\%$. What is the velocity of the star?