Optics PYQ — Page 7

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 :

In Young's double slit experiment, monochromatic light of wavelength $5000\overset{\circ }{A}$ is used. The slits are $1.0\mathrm{mm}$ apart and screen is placed at $1.0m$ away from slits. The distance from the centre of the screen where intensity becomes half of the maximum intensity for the first time is ______$\times {10}^{-6}m.$

Given below are two statements : Statement (I) : When an object is placed at the centre of curvature of a concave lens, image is formed at the centre of curvature of the lens on the other side. Statement (II) : Concave lens always forms a virtual and erect image. In the light of the above statements, choose the correct answer from the options given below :

Critical angle of incidence for a pair of optical media is $45^{\circ}$. The refractive indices of first and second media are in the ratio:

A microwave of wavelength $2.0\mathrm{cm}$ falls normally on a slit of width $4.0\mathrm{cm}.$ The angular spread of the central maxima of the diffraction pattern obtained on a screen $1.5m$ away from the slit, will be:

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

Light from a point source in air falls on a convex curved surface of radius $20\mathrm{cm}$ and refractive index $1.5$. If the source is located at $100\mathrm{cm}$ from the convex surface, the image will be formed at ______ $\mathrm{cm}$ from the object.

In a Young's double slit experiment, the intensity at a point is $\left(\frac{1}{4}\right)^{\text {th }}$ of the maximum intensity, the minimum distance of the point from the central maximum is ________ $\mu \mathrm{m}$. (Given : $\lambda=600 \mathrm{~nm}, \mathrm{~d}=1.0 \mathrm{~mm}, \mathrm{D}=1.0 \mathrm{~m}$ )

Two slits are $1 \mathrm{~mm}$ apart and the screen is located $1 \mathrm{~m}$ away from the slits. A light of wavelength $500 \mathrm{~nm}$ is used. The width of each slit to obtain 10 maxima of the double slit pattern within the central maximum of the single slit pattern is _____$\times 10^{-4} \mathrm{~m}$

A biconvex lens of refractive index $1.5$ has a focal length of $20\mathrm{cm}$ in air. Its focal length when immersed in a liquid of refractive index $1.6$ will be:

The distance between object and its $3$ times magnified virtual image as produced by a convex lens is $20\mathrm{cm}.$ The focal length of the lens used is ________ $\mathrm{cm}.$

In a single slit diffraction pattern, a light of wavelength $6000\overset{o}{A}$ is used. The distance between the first and third minima in the diffraction pattern is found to be $3\mathrm{mm}$ when the screen is placed $50\mathrm{cm}$ away from slits. The width of the slit is ____$\times {10}^{-4}m$.

A monochromatic light of wavelength $6000\overset{o}{A}$ is incident on the single slit of width $0.01\mathrm{mm}$. If the diffraction pattern is formed at the focus of the convex lens of focal length $20\mathrm{cm}$, the linear width of the central maximum is :

In finding out refractive index of glass slab the following observations were made through travelling microscope 50 vernier scale division $=49 \mathrm{MSD} ; 20$ divisions on main scale in each $\mathrm{cm}$ For mark on paper $\mathrm{MSR}=8.45 \mathrm{~cm}, \mathrm{VC}=26$ For mark on paper seen through slab MSR $=7.12 \mathrm{~cm}, V C=41$ For powder particle on the top surface of the glass slab $\mathrm{MSR}=4.05 \mathrm{~cm}, \mathrm{VC}=1$ (MSR $=$ Main Scale Reading, VC $=$ Vernier Coincidence) Refractive index of the glass slab is :

The position of the image formed by the combination of lenses is : 

Light emerges out of a convex lens when a source of light kept at its focus. The shape of wavefront of the light is :

A convex mirror of radius of curvature $30\mathrm{cm}$ forms an image that is half the size of the object. The object distance is :

A parallel beam of monochromatic light of wavelength $600 \mathrm{~nm}$ passes through single slit of $0.4 \mathrm{~mm}$ width. Angular divergence corresponding to second order minima would be ______ $\times 10^{-3} \mathrm{rad}$.

When unpolarized light is incident at an angle of $60^{\circ}$ on a transparent medium from air. The reflected ray is completely polarized. The angle of refraction in the medium is

Two wavelengths $\lambda_1$ and $\lambda_2$ are used in Young's double slit experiment. $\lambda_1=450 \mathrm{~nm}$ and $\lambda_2=650 \mathrm{~nm}$. The minimum order of fringe produced by $\lambda_2$ which overlaps with the fringe produced by $\lambda_1$ is $n$. The value of $n$ is _____.

A light ray is incident on a glass slab of thickness $4 \sqrt{3} \mathrm{~cm}$ and refractive index $\sqrt{2}$ . The angle of incidence is equal to the critical angle for the glass slab with air. The lateral displacement of ray after passing through glass slab is _____ $\mathrm{cm}$. $\left(\right.$ Given $\left.\sin 15^{\circ}=0.25\right)$

Two immiscible liquids of refractive indices $\frac{8}{5}$ and $\frac{3}{2}$ respectively are put in a beaker as shown in the figure. The height of each column is $6\mathrm{cm}$. A coin is placed at the bottom of the beaker. For near normal vision, the apparent depth of the coin is $\frac{\alpha }{4}\mathrm{cm}$. The value of $\alpha$ is _______. 

A microscope is focused on an object at the bottom of a bucket. If liquid with refractive index $\frac{5}{3}$ is poured inside the bucket, then microscope have to be raised by $30\mathrm{cm}$ to focus the object again. The height of the liquid in the bucket is :

A point object $O$ is placed in front of two thin symmetrical coaxial convex lenses ${L}_{1}$ and ${L}_{2}$ with focal length $24\mathrm{cm}$ and $9\mathrm{cm}$ respectively. The distance between two lenses is $10\mathrm{cm}$ and the object is placed $6\mathrm{cm}$ away from lens ${L}_{1}$ as shown in the figure. The distance between the object and the image formed by the system of two lenses is _____________ $\mathrm{cm}$