Consider a ray of light incident from air onto a slab of glass (refractive index n) of width d, at an angle θ. The phase difference between the ray reflected by the top surface of the glass and the bottom surface is

(a)$\frac{4\mathit{\pi }\mathit{d}}{\mathit{\lambda }}$ ( $1-\frac{1}{{\mathit{n}}^2}{\mathit{s}\mathit{i}\mathit{n}}^2\mathit{\theta }$ )1/2+ $\mathit{\pi }$

(b)$\frac{4\mathit{\pi }\mathit{d}}{\mathit{\lambda }}$ ( $1-\frac{1}{{\mathit{n}}^2}{\mathit{s}\mathit{i}\mathit{n}}^2\mathit{\theta }$ )1/2

(c)$\frac{4\mathit{\pi }\mathit{d}}{\mathit{\lambda }}$ ( $1-\frac{1}{{\mathit{n}}^2}{\mathit{s}\mathit{i}\mathit{n}}^2\mathit{\theta }$ )1/2+ $\mathit{\pi }$ /2

(d) ( $1-\frac{1}{{\mathit{n}}^2}{\mathit{s}\mathit{i}\mathit{n}}^2\mathit{\theta }$ )1/2+ $2\mathit{\pi }$

The angle between the plane of vibration and plane of polarization is

A uniform thin rope of length 12 m and mass 6 kg hangs vertically from a rigid support and a block of mass 2 kg is attached to its free end. A transverse short wave-train of wavelength 6 cm is produced at the lower end of the rope. What is the wavelength of the wave train (in cm) when it reaches the top of the rope?
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In the Young's double slit experiment, the distance between the slits varies in time as d(t) = d? + a? sin(ωt); where d?, ω and a? are constants. The difference between the largest fringe width and the smallest fringe width obtained over time is given as :

An unpolarised light beam of intensity 2l₀ is passed through a polaroid P and then through another polaroid Q which is oriented is such a way that its passing axis makes an angle of 30° relative to that of P. The intensity of the emergent light is
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In Young’s double slit experiment the two slits are 0.6mm distance apart. Interference pattern is observed on a screen at a distance 80cm from the slits. The first dark fringe is observed on the screen directly opposite to one of the slits. The wavelength of light will be__________nm.