A beam of light consisting of two wavelengths 7000Ao and 5500Ao is used to obtain interference pattern in Young's double slit experiment. The distance between the slits is 2.5mm and the distance between the plane of slits and the screen is 150cm. The least distance from the central fringe, where the bright fringes due to both the wavelengths coincide, is n×10–5m. The value of n is _____.
Held on 6 Apr 2023 · Verified 6 Jul 2026.
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When an unpolarized light falls at a particular angle on a glass plate (placed in air), it is observed that the reflected beam is linearly polarized. The angle of refracted beam with respect to the normal is $\_\_\_\_$. $\left(\tan ^{-1}(1.52)=57.7^{\circ}\right.$, refractive indices of air and glass are 1.00 and 1.52, respectively.)
In Young's double slit experiment, the fringe width is β. If the wavelength of light is doubled and the slit separation is halved, the new fringe width is:
A biconvex lens is formed by using two thin planoconvex lenses, as shown in the figure. The refractive index and radius of curved surfaces are also mentioned in figure. When an object is placed on the left side of lens at a distance of 30 cm from the biconvex lens, the magnification of the image will be : 
A collimated beam of light of diameter 2 mm is propagating along $x$-axis. The beam is required to be expanded in a collimated beam of diameter 14 mm using a system of two convex lenses. If first lens has focal length 40 mm, then the focal length of second lens is $\_\_\_\_$ mm.
Light ray incident along a vector $\vec{AO}$ $(\vec{AO} = 2\hat{i}-3\hat{j})$ emerges out along vector $\vec{OB}$ $(\vec{OB} = C\hat{i}-4\hat{j})$ as shown in the figure below. The value of $C$ is ________. 
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