A beam of unpolarised light of intensity $$I_0$$ is passed through a polaroid $$A$$ and then through another polaroid $$B$$ which is oriented so that its principal plane makes an angle of $$45^{\circ}$$ relative to that of $$A$$. The intensity of emergent light is:

The diffraction pattern of a light of wavelength $$400 \mathrm{~nm}$$ diffracting from a slit of width $$0.2 \mathrm{~mm}$$ is focused on the focal plane of a convex lens of focal length $$100 \mathrm{~cm}$$. The width of the $$1^{\text {st }}$$ secondary maxima will be :

In Young's double slit experiment, light from two identical sources are superimposing on a screen. The path difference between the two lights reaching at a point on the screen is $$7 \lambda / 4$$. The ratio of intensity of fringe at this point with respect to the maximum intensity of the fringe is :

When a polaroid sheet is rotated between two crossed polaroids then the transmitted light intensity will be maximum for a rotation of :