$A$ thin slice is cut out of a glass cylinder along a plane parallel to its axis. The slice is placed on a flat glass plate as shown. The observed interference fringes from this combination shall be

$A$ ray of light of intensity $I$ is incident on a parallel glass slab at a point $A$ as shown in the figure. It undergoes partial reflection and refraction. At each reflection,$25\%$ of the incident energy is reflected. The rays $AB$ and $A^1B^1$ undergo interference. The ratio $I_{\text{max}} / I_{\text{min}}$ is (in $: 1$)

In a Fresnel biprism experiment,which of the following light sources is used to identify the central fringe?

$A$ very thin transparent film (like a soap bubble) is viewed in white light. The color of the film appears .......

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?

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: