In two separate setups for a Biprism experiment using the same wavelength,fringes of equal width are obtained. If the ratio of slit separation is $2:3$,then the ratio of the distance between the slit and the screen in the two setups is:

The colors seen on an oil film floating on the surface of water are due to interference. What should be the order of the thickness of the oil film?

What is the minimum thickness of a thin film required for constructive interference in the reflected light from it (in $ nm$)? Given, the refractive index of the film $= 1.5$, wavelength of the light incident on the film $= 600 \, nm$.

$A$ thin oil film of refractive index $1.2$ floats on the surface of water $(\mu = \frac{4}{3})$. When light of wavelength $\lambda = 9.6 \times 10^{-7} \ m$ falls normally on the film from air,it appears dark when seen normally. What is the minimum change in its thickness for which it will appear bright in normally reflected light by the same light?

The beautiful iridescent (like a rainbow) colors on the wings of a tropical or morpho butterfly are due to

In a biprism experiment,if the $5^{\text{th}}$ bright band with wavelength $\lambda_1$ coincides with the $6^{\text{th}}$ dark band with wavelength $\lambda_2$,then the ratio $(\lambda_1 / \lambda_2)$ is: