In a binary star system, two stars orbit a common point and move so that they are always in diametrically opposite positions. Light from both stars reaches an observer on earth. Assume that both stars emit light of wavelength $6.58\times {10}^{-7} \mathrm{m}$.

b. When the stars are in the position shown in the diagram, the observer on earth measures wavelengths in the received light $6.50\times {10}^{-7}\mathrm{m}$ and $6.76\times {10}^{-7}\mathrm{m}$. Determine the speed of each stars.

A ball of mass $\mathrm{m}$ is attached to two identical springs of spring constant $\mathrm{k}$ as shown. Initially, the springs have their natural lengths. The ball is displaced to a small distance to the right and then released. What is the period of oscillations of the ball?

 Light of wavelength $\lambda$ is incident on two parallel slits and an interference pattern is formed behind the slit.The separation of the slit and the width of the slit both decreased. Which of the following is correct about the separation and width of the bright fringes?

A coherent light of wavelength $\mathrm{\lambda }$  is incident on two parallel slits that are separated by a distance $d$. Angle $\mathrm{\theta }$ is the smallest separation for which the two rays showed interference destructively on a screen far from the slit.

Which of the following could be correct?