The approximate thickness of an oil film required to observe the interference of light (due to which it appears coloured) is .......

What is the effect on Fresnel's biprism experiment when white light is used?

In a biprism experiment, the fifth dark fringe is obtained at a point. $A$ thin transparent film of refractive index '$\mu$' is placed in one of the interfering paths. Now, the $7^{th}$ bright fringe is obtained at the same point. If '$\lambda$' is the wavelength of light used, the thickness of the film is equal to:

$A$ 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

White light may be considered to be a mixture of waves with $\lambda$ ranging between $3900\ \mathring A$ and $7800\ \mathring A$. An oil film of thickness $10,000\ \mathring A$ is examined normally by reflected light. If $\mu = 1.4$,then the film appears bright for

In a biprism experiment,monochromatic light of wavelength $\lambda$ is used. The distance between two coherent sources is kept constant. If the distance between the slit and the eyepiece $(D)$ is varied as $D_{1}, D_{2}, D_{3}$ and $D_{4}$,and the corresponding measured fringe widths are $z_{1}, z_{2}, z_{3}$ and $z_{4}$,then: