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?

A light is incident essentially normally on a thin film of thickness $\mathrm{t}$ and refractive index $1.5$, The film is on a transparent glass of refractive index $2.5$. Which of the following condition of the wavelength $\lambda$ in oil leads to the destructive interference of the reflective light