A beam of plane polarized light of large cross-sectional area and uniform intensity of $3.3{\mathrm{W}\mathrm{m}}^{-2}$ falls normally on a polarizer (cross sectional area $3*{10}^{-4}{\mathrm{m}}^2$ ) which rotates about its axis with an angular speed of $31.4\mathrm{r}\mathrm{a}\mathrm{d}/\mathrm{s}$ . The energy of light passing through the polariser per revolution, is close to:

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.