A star is moving away from an observer with a speed of $500 kms^{-1}$. Calculate the Doppter shift if the wavelength of light emitted by the star is $6000 A^{\circ}$

Question

$\begin{array}{1 1} 10^{\circ}A \\ 20^{\circ}A \\ 30^{\circ}A \\ 40^{\circ}A \end{array} $