Optics PYQ — Page 16

Formation of real image using a biconvex lens is shown below:  If the whole set up is immersed in water without disturbing the object and the screen positions, what will one observe on the screen?

Consider a Young's double slit experiment as shown in figure. What should be the slit separation $d$ in terms of wavelength $\lambda$ such that the first minima occurs directly in front of the slit $({S}_{1})$ ? 

Consider a tank made of glass (refractive index $1.5$ ) with a thick bottom. It is filled with a liquid of refractive index $\mu .$ A student finds that, irrespective of what the incident angle $i$ (see figure) is for a beam of light entering the liquid, the light reflected from the liquid glass interface is never completely polarized. For this to happen, the minimum value of $\mu$ is: 

An upright object is placed at a distance of $40 cm$ in front of a convergent lens of focal length $20 cm.$ A convergent mirror of focal length $10 cm$ is placed at a distance of $60 cm$ on the other side of the lens. The position and size of the final image will be:

An object is at a distance of $20 \mathrm{~m}$ from a convex lens of focal length $0.3 \mathrm{~m}$. The lens forms an image of the object. If the object moves away from the lens at a speed of $5 \mathrm{~m} / \mathrm{s}$ the speed and direction of the image will be

A transparent cube of side $d$, made of a material of refractive index ${\mu }_{2}$, is immersed in a liquid of refractive index ${\mu }_{1}({\mu }_{1}<{\mu }_{2})$. A ray is incident on the face $AB$ at an angle $\theta$ (shown in the figure). Total internal reflection takes place at the point $E$ on the face $BC.$  Then, $\theta$ must satisfy

A thin convex lens $L$ (refractive index $=1.5$ ) is placed on a plane mirror $M$. When a pin is placed at $A$, such that $OA=18 cm,$ its real inverted image is formed at $A$ itself, as shown in figure. When liquid of refractive index ${\mu }_{l}$ is put between the lens and the mirror, the pin has to be moved to ${A}^{'},$ such that $O{A}^{'}=27 cm,$ to get its inverted real image at $A'$ itself. The value of ${\mu }_{l}$ will be 

A system of three polarizers ${P}_{1},{P}_{2},{P}_{3}$ is set up such that the pass axis of ${P}_{3}$ is crossed with respect to that of ${P}_{1}$ . The pass axis of ${P}_{2}$ is inclined at ${60}^{o}$ to the pass axis of ${P}_{3}.$ When a beam of unpolarized light of intensity ${I}_{o}$ is incident on ${P}_{1},$ the intensity of light transmitted by the three polarizers is $I$ . The ratio $({I}_{o}/I)$ equals (nearly):

A ray of light $AO$ in vacuum is incident on a glass slab at angle $60^{\circ}$ and refracted at angle $30^{\circ}$ along $OB$ as shown in the figure. The optical path length of light ray from $A$ to $B$ is: 

A point source of light, S is placed at a distance L in front of the center of plane mirror of width d which is hanging vertically on a wall. A man walks in front of the mirror along a line parallel to the mirror, at a distance 2L as shown below. The distance over which the man can see the image of the light source in the mirror is: 

A plano-convex lens of refractive index ${\mu }_{1}$ and focal length ${f}_{1}$ is kept in contact with another plano-concave lens of refractive index ${\mu }_{2}$ and focal length ${f}_{2}.$ If the radius of curvature of their spherical faces is $R$ each and ${f}_{1}=2{f}_{2},$ the ${\mu }_{1}$ and ${\mu }_{2}$ are related as:

A plano - convex lens (focal length ${f}_{2}$ , refractive index ${\mu }_{2},$ radius of curvature R) fits exactly into a plano - concave lens (focal length ${f}_{1},$ refractive index ${\mu }_{1},$ radius of curvature R). Their plane surfaces are parallel to each other. Then, the focal length of the combination will be:

A monochromatic light is incident at a certain angle on an equilateral triangular prism and suffers minimum deviation. If the refractive index of the material of the prism is $\sqrt{3}$, then the angle of incidence is :

A light wave is incident normally on a glass slab of refractive index $1.5.$ If $4%$ of light gets reflected and the amplitude of the electric field of the incident light is $30\frac{V}{m},$ then the amplitude of the electric field for the wave propagating in the glass medium will be:

A convex lens of focal length $20 cm$ produces images of the same magnification 2 when an object is kept at two distances ${x}_{1}$ and ${x}_{2}({x}_{1}>{x}_{2})$ from the lens. The ratio of ${x}_{1}$ and ${x}_{2}$ is:

A convex lens (of focal length $20 cm$ ) and a concave mirror, having their principal axes along the same lines, are kept $80 cm$ apart from each other. The concave mirror is to the right of the convex lens. When an object is kept at a distance of $30 cm$ to the left of the convex lens, its image remains at the same position even if the concave mirror is removed. The maximum distance of the object for which this concave mirror, by itself would produce a virtual image would be:

A convex lens is put $10 cm$ from a light source and it makes a sharp image on a screen, kept $10 cm$ from the lens. Now a glass block (refractive index 1.5) of $1.5 cm$ thickness is placed in between the light source and the lens. To get the sharp image again, the screen is shifted by a distance $d.$ Then $d$ is: 

A concave mirror has radius of curvature of $40 cm.$ It is at the bottom of a glass that has water filled up to $5 cm$ (see figure). If a small particle is floating on the surface of water, its image as seen, from directly above the glass, is at a distance $d$ from the surface of water. The value of $d$ is close to: (Refractive index of water $=1.33)$ 

A concave mirror for face viewing has a focal length of $0.4 m$. The distance at which you hold the mirror from your face in order to see your image upright with a magnification of $5$ is

Unpolarized light of intensity $I$ passes through an ideal polariser $A$. Another identical polariser $B$ is placed behind $A$. The intensity of light beyond B is found to be $\frac{I}{2}$. Now another identical polariser $C$ is placed between $A$ and $B$. The intensity beyond B is now found to be $\frac{I}{8}$ . The angle between polariser $A$ and $C$ is

Unpolarized light of intensity $I$ is incident on a system of two polarizers, $A$ followed by $B$. The intensity of emergent light is $\frac{I}{2}$ . If a third the polarizer $C$ is placed between $A$ and $B$ the intensity of emergent light is reduced to $\frac{I}{3}$ . The angle between the polarizers $A$ and $C$ is $\theta$ , then

The angular width of the central maximum in a single slit diffraction pattern is $60^{\circ}$ . The width of the slit is $1\mu m$. The slit is illuminated by monochromatic plane waves. If another slit of the same width is made near it, Young's fringes can be observed on a screen placed at a distance $50 \mathrm{cm}$ from the slits. If the observed fringe width is $1 \mathrm{cm}$, what is slit separation distance? (i.e., the distance between the centres of each slit.)

Light of wavelength $550 \mathrm{~nm}$ falls normally on a slit of width $22.0 \times 10^{-5} \mathrm{~cm}$. The angular position of the second minima from the central maximum will be (in radians)

Light of wavelength $550\mathrm{nm}$ falls normally on a slit of width $22.0\times {10}^{-5}\mathrm{cm}$. The angular position of the second minima from the central maximum will be (in radians):