On a rainy day,a small oil film on water shows brilliant colours. This is due to:

In a biprism experiment, a steady interference pattern is observed on the screen kept at a distance of $100 \text{ cm}$ using a light of wavelength $5000 \text{ Å}$. Without changing the distance between the virtual sources of the slit, the source of light is replaced by a source of wavelength $6400 \text{ Å}$. Now, to reduce the fringe width by $20\%$ of its initial value, the screen should be moved

When a mica sheet of thickness $7 \ \mu m$ and refractive index $\mu = 1.6$ is placed in the path of one of the interfering beams in a biprism experiment, the central fringe shifts to the position of the seventh bright fringe. The wavelength of the light used is $............ \ \mathring{A}$.

Which of the following produces coherent waves?

In a Fresnel's biprism experiment,coherent sources are obtained by which of the following phenomena?

In a biprism experiment,the fringe width is $0.6 \ mm$. The distance between the $6^{th}$ dark fringe and the $8^{th}$ bright fringe on the same side of the central bright fringe is: (in $mm$)