Question 1 : The power of a convex lens of focal length $2$ metre will be:

Question 3 : If a drop of water is introduced between the glass plate and a convex lens in a Newton's ring system, the ring system

Question 4 : The nature of image formed when an object is placed near to a concave lens is _____

Question 5 : How will the image formed by a convex lens be affected if the central portion of lens is wrapped in black paper?<br>

Question 7 : It is first face of a prism which disperses white light. The statement is

Question 8 : Assertion: The diamond shines due to multiple total internal reflections. Reason: The critical angle for diamond is 24.4$^o$.

Question 9 : A manufacturer uses a concave lens instead of a convex lens in a magnifying glass by mistake. What will be the effect on the working of the lens?

Question 10 : A rod of length 10 cm lies along the principal axis of a concave mirror of focal length 10 cm in such away that the end closer to the pole is 20 cm away from it. Find the length of the image.

Question 11 : The distance between an object and its real image produced by a converging lens is $0.72\ m$. The magnification is $2$. What will be the magnification when the object is moved by $0.04\ m$ towards the lens?

Question 12 : What is the power of the lens, if the far point of a short sighted eye is $200\ cm$?

Question 13 : An object is placed on the principal axis of a convex mirror of focal length 15 cm. If the distance of the object from the mirror is 30 cm, determine the image distance

Question 14 : A converging lens of refractive index $1.5$ kept in a liquid medium having the same refractive index. What would be the focal length of the lens in this medium?<br/>

Question 15 : In an experiment to trace the path of a ray of light through a glass prism for different values of angle of incidence a student would find that the emergent ray:

Question 18 : Assertion: Rainy clouds appear dark from below. Reason: There is not sufficient light which can be scattered by these clouds.

Question 19 : Ray optics fail when the size of the obstacle is :

Question 20 : State the condition for the following:&#160;A lens has both its focal lengths equal.<br/>

Question 21 : Which of the prism is used to see infrared spectrum of light

Question 22 : The frequency of a light wave in a material is $2\times 10^{14} Hz$ and wavelength is $5000\overset {\circ}{A}$. The refractive index of material will be :

Question 23 : While obtaining the image of a candle by a convex lens, if lower half portion of the lens is blackened to make it opaque completely, then the intensity of the image will be :

Question 24 : Two thin lenses of focal lengths $f_{1} and f_{2}$ are in contact and coaxial. The power of the combination is :<br/>

Question 25 : A satisfactory photographic print is obtained when the exposure time is $10\ sec$ at a distance of $2\ m$ from a $60\ cd$ lamp. The time of exposure required for the same quality print at a distance of $4\ m$ from a $120\ cd$ lamp is

Question 26 : How will the image formed by a convex lens be affected if thecentral portion of lens is wrapped in black paper ?

Question 27 : Height of the image of an object on an principal axis produced by a convex lens is double the focal length of lens is $20 cm$, then image distance from the lens is:

Question 30 : The angle of minimum deviation for a prism is $40^{o}$ and the angle of the prism is $60^{o}$. The angle of incidence in this position will be

Question 32 : A light ray travels at some angle (not head on) from water in a rectangular aquarium, through the glass side, and out into air . The indices if refraction for water, glass, and air are 1.33, about 1.6, and 1.0, respectively.<br/>Rank the material;s according to the angles of refraction&#160; made by the light ray with the normal in each, greatest first.

Question 33 : The sun appears red at the time of sun-rise and sun-set. This is because:

Question 34 : The power of a lens whose focal length is one metre is ______ dioptre.

Question 35 : Optical fibres transmit light along its axis, by the process of :

Question 36 : If the light moving in a straight line bends by a small but fixed angle, it may be a case of<br>$(i)$reflection<br>$(ii)$refraction<br>$(iii)$diffraction<br>$(iv)$dispersion<br>

Question 38 : If $f$ is focal length of the lens in $cm$, then the power of a lens is equal to:

Question 41 : The magnifying power of a simple microscope can be increased if we use eye piece of :

Question 42 : The image formed behind a mirror and that formed behind a magnifying glass

Question 44 : The power of two convex lenses $A$ and $B$ are $8$ diopters and $4$ diopters respectively. If they are to be used as a simple microscope, the magnification of

Question 45 : If critical angle for a material to air is${30^0}$, the refractive index of the material will be.

Question 46 : Assertion: If refractive index of one medium is equal to refractive index of second medium, then beam does not bend at all. Reason: The bending of light does not depend on refractive indices of media.

Question 48 : A ray of light is normally incident on one face of an equilateral glass prism. What is the angle of incidence on the first face&#160;of the prism ?

Question 49 : A convex lens of focal length $12.5cm$ is used as a simple microscope. When the image is formed at infinite. Magnification is ________ (Near point for the normal vision is $25cm$)

Question 50 : An object is placed at a distance of $5$ cm from a convex lens of focal length $10$ cm, then the image

Question 51 : Let the $\mathrm{x}-\mathrm{y}$ plane be the boundary between two transparent media. Medium 1 in $\mathrm{z}\geq 0$ has a refractive index of $\sqrt{2}$ and medium 2 with $\mathrm{z}&lt; 0$ has a refractive index of $\sqrt{3}$. A ray of light in medium 1 given by the vector $\vec{\mathrm{A}}=6\sqrt{3}\hat{\mathrm{i}}+8\sqrt{3}\hat{\mathrm{j}} + 10\hat{\mathrm{k}}$ is incident on the plane of separation. The angle of refraction in medium 2 is<br>

Question 52 : The magnifying power of a microscope with an objective of $5 mm$ focal length is $400.$ The length of its tube is $20 cm.$ Then the focal length of the eye-piece is

Question 53 : Consider telecommunication through optical fibres. Which of the following statements is not true?

Question 54 : A student has to focus his compound microscope to observe a preparedslide showing different stages of binary fission in Amoeba. The steps he islikely to follow are listed below in a haphazard manner :<br>I. Adjust the diaphragm and the mirror of the microscope so thatsufficient light may enter to illuminate the slide.<br>II. Fix the slide on the stage carefully.<br>III. Adjust the microscope to high power and focus.<br>IV. Adjust the microscope to low power and focus.<br>The correct sequence of the above steps to observe the slide under themicroscope is

Question 55 : Ratio of the sine of angle of incidence to the sine of angle of reflection is:

Question 56 : A beam of a parallel rays is brought to a focus by a convex lens. If a thin concave lens of equal focal length is joined to the convex lens, the focus will be

Question 57 : The R.I. of a diverging meniscus lens is $1.5$ and its radii of curvature are $3$ cm and $4$ cm. &#160;The position of the image, if an object is placed $12$ cm in front of the lens is &#160;&#160;

Question 58 : The refractive index of water with respect to air is1.33. The refractive index of air with respect towater will be

Question 59 : Assertion: A Diamond sparkles more than a glass imitation cut to the same shape. Reason: The refractive index of diamond is less than that of glass.

Question 60 : A lamp is hanging at a height of $4$ $m$ above a table. The lamp is lowered by $1$ $m$. The percentage increase in illuminance is

Question 61 : Which&#160;of the following colours of white light deviated most when passes through a&#160;prism. ?

Question 62 : If the tube length of astronomical telescope is $96$cm and magnifying power is $15$ for normal setting, then the focal length of the objective is _________cm.

Question 63 : A thin convex lens of focal length $f$ made of crown glass is immersed in a liquid of refractive index ${ \mu&#160; }_{ r }.\left( { \mu&#160; }_{ l }&gt;{ \mu&#160; }_{ c } \right) $ where ${ \mu&#160; }_{ c }$ is the refractive index of the crown glass.<br/>The convex lens now is

Question 64 : A clear transparent glass sphere $(\mu = 1.5)$ of radius $R$ is immersed in a liquid of refractive index $1.25$. A parallel beam of light incident on it will converge to a point. The distance of this point from the center will be

Question 65 : The power of lens is +2 Dioptre. What is the focal length of this mirror?

Question 67 : A swimming pool appears to be raised by $6 m$ when viewed normally. What is the refractive index of water if the actual depth of the swim-ming pool is $24 m$?

Question 68 : Two thin lenses are in contact and the focal length of the combination is $80\ cm$. If the focal length of one lens is $20\ cm$, then the power of the other lens will be

Question 69 : A ray of light enters from a rarer to a denser medium. The angle of incidence is $i$. Then the reflected and refracted rays are mutually perpendicular to each other. The critical angle for the pair of media is

Question 70 : A convergent doublet of separated lenses, corrected for spherical aberration, has resultant focal length of $10cm$. The separation between the two lenses is $2cm$. The focal lengths of the component lenses

Question 71 : A concave mirror is placed on a horizontal table, with its axis directed vertically upwards. Let O be the pole of the mirror and C its centre of curvature. A point object is placed at C. It has a real image, also, located at C (a condition called auto-collimation). If the mirror is now filled with water, the image will be

Question 72 : If the angle of incidence is equal to critical angle,then the angle of refractive is ( C ):

Question 73 : A concave mirror and a convex lens both have same focal length in air. When they are submerged in glycerine, the focal length :

Question 74 : The focal length of a convex lens when placed in air and then in water will :

Question 75 : Focal power of a plano-concave lens of refractive index 1.5 and of radius of curvature 50cm is

Question 76 : A double convex lens of focal length $6$ cm is made of glass of refractive index $1.5$. The radius of curvature of one surface which is double that of the other surface will be

Question 77 : Light of wavelength$\displaystyle 6600\overset { \circ }{ A }$ travelling in air gets refracted in water. If the speed of light in air is$\displaystyle 3\times { 10 }^{ 8 }{ m }/{ s }$ and R.I of water is 4/3. Find frequency of light in air.

Question 78 : The absolute refractive indices of water glass and diamond are 1.77, 1.50 and 2.72 respectively, which medium is most optically denser?

Question 79 : Assertion: An empty test tube dipped into water in a breaker appears silver,When viewed from a suitable direction. Reason: Due to refraction of light, the substance in water appears silvery.

Question 80 : A convex lens is used to form an image of an object ona screen. If the upper half of the lens is blackened sothat it becomes opaque. Then

Question 82 : Refraction index of water is 4/3. Calculate speed of light in water.

Question 83 : A $60\ watt$ bulb is hung over the center of a table $4m \times 4\ m$ at a height of $3\ m$. The ratio of the intensities of illumination at a point on the centre of the edge an don the corner of the table is

Question 84 : The focal length of a convex lens of glass $(\mu =1.5)$ is $2cm$. The focal length of the lens when immersed in a liquid of refractive index $1.25$ will be :

Question 85 : A convex lens of focal length $30cm$ produce $5$ times magnified real image of an object. What is the object distance?

Question 87 : For two position of lens, the images are obtained on a fixed screen. If the size of the object is 2 cm and size of diminished image is 0.5 cm, the size of the other image will be <br>

Question 88 : A thick plane mirror shows a number of images of the filament of an electric bulb. Of these, the brightest image is the -

Question 89 : A person near point is $50\ cm$and his far point is $3\ m$. Powers of the lenses he requires for<br>(i) reading<br>(ii) seeing distant stars are

Question 90 : A diverging meniscus lens has a focal length of -20 cm. If the lens is held 10 cm from the object, the magnification is :

Question 91 : Two vertical plane mirrors are inclined at an angle of $60^0$ with each other. A ray of light travelling horizontally is reflected first from one mirror and then from the other. The resultant deviation is

Question 92 : <p>An object placed $10 cm$ in front of a lens has an image $20<br>cm$ behind the lens. What is the power of the lens (In dioptre)?</p>

Question 93 : A microscope is focussed on an ink mark on the top of a table. If we place a glass slab of $3$cm thick on it, how should the microscope be moved to focus the ink spot again? The refractive index of glass is $1.5$.

Question 94 : A&#160;convex lens of focal length 15 cm is placed on a plane mirror. An object is&#160;placed at 30 cm from the lens. The image will be

Question 95 : If the image formed by a thin convex lens of power $P$ has magnification $m$ then image distance $v$ is

Question 96 : A lens made of material of Refractive index $\mu _{ 2 }$ is surrounded by a medium of Refractive Index $\mu _{ 1 }$. The focal length f is related as&#160; :

Question 97 : A ray of light is incident on glass slab making an angle of incidence $sin^{-1} \left( \dfrac{\sqrt 3}{2} \right )$. What will be the angle of refraction in glass of refractive index 1.5?

Question 98 : When a thin convex lens is put in contact with a thin concave lens of the same focal length, the resultant combination has focal length equal to :<br/>

Question 99 : Two thin lenses of focal lengths 20 cm and 25 cm areplaced in contact. The effective power of the combination is

Question 100 : A film projector magnifies a&#160;$\displaystyle 100\ { cm }^{ 2 }$ film strip on a screen. If the linear magnification is $4$, the area of the magnified film on the screen is be&#160;$\displaystyle 1000\ { cm }^{ 2 }$

Question 101 : A convex lens of focal length $f$ is placed somewhere in between the object and a screen. The distance between object and screen is $x$. If magnification produced is $m$, the focal length of the lens is:

Question 102 : The angle of crown glass $(\mu=1.52)$ prism is $5^o$. What should be the angle of flint glass $(\mu=1.63)$ prism so that the two prisms together may be used in a direct vision spectroscope?<br>

Question 103 : What happens when a ray of light is made to fall on a mirror along the normal?<br/>

Question 104 : Two thin lenses have a combined power of $+9D$. When they are separated by a distance of $20\ cm$, their equivalent power becomes $+ \dfrac {27}{5}D$, then their individual powers are

Question 105 : An electron microscope is operated at $40 Kv$ . The ratio of resolving power of this microscope and another one which uses yellow light of wavelength $6\times10^7$ is :<br/>

Question 106 : The focal length of a thin biconvex lens is 20 cm. when an object is moved from a distance of 25 cm in front of it to 50 cm, the magnification of its image changes from $m_{25}$ to $m_{50}$. The ratio of $m_{25}$ to $m_{50}$ is :

Question 107 : A microscope has an objective of focal length $1.5$ cm and an eyepiece of focal length $2.5 cm$. If the distance between objective and eyepiece is $20.5 cm$, what is the magnification produced when the final image is at infinite distance away?

Question 108 : A monochromatic light passes through a glass slab $\left (\mu = \dfrac {3}{2}\right )$ a thickness $90\ cm$ in time $t_{1}$. If it takes $t_{2}$ to travel the same distance through water $\left (\mu = \dfrac {4}{3}\right )$. The value of $(t_{1} - t_{2})$ is :

Question 109 : Two identical double convex lenses each of focal length f are made of glass $\mu=\dfrac{3}{2}.$ If R is the radius of curvature of each of the four faces, then<br/>

Question 110 : A diverging meniscus lens of 1.5 refractive index has concave surface of radii 3 and 4 cm.The position of the image, if an object is placed 12 cm in front of the lens, is

Question 111 : A flim projector magnifies a flim of area $100 $ square centimeter on screen. If linear magnification is $4$ then area of magnified image on screen will be-

Question 112 : Assertion: Although the surfaces of goggle lenses are curved, it does not have any power. Reason: In case of goggle, both the curved surfaces have equal radii of curvature and have center of curvature on the same side.

Question 113 : A convex lens forms a real image 9 cm long on a screen. Without altering the position of the object and the screen, the lens is displaced and we get again a real image 4 cm long on the screen. Then the length of the object is<br>

Question 114 : A water film is formed on a glass-block. A light ray is incident on water film from air at an angle of$\displaystyle { 60 }^{ \circ }$ with the normal. The angle of incidence on glass slab is<br>($\displaystyle { \mu }_{ g } = 1.5,{ \mu }_{ w } = \frac { 4 }{ 3 }$)

Question 115 : A symmetric double convex lens is cut in two equal parts by a plane perpendicular to the principle axis. If the power of the original lens is $4D$, the power of a cut lens will be

Question 116 : Let the x-z plane be the boundary between two transparent media. Medium $1$ in $z\ge 0$ has a refractive index of $\sqrt { 2 } $ and medium $2$ with $z&lt; 0$ has refractive index of $\sqrt { 3 } $. A ray of light in medium $1$ given by the vector $\vec { A } =6\sqrt { 3 } \hat { i } +8\sqrt { 3 } \hat { j } -10\hat { k } $ is incident on the plane of separation. The angle of refraction in medium $2$ is:

Question 117 : The angle between the incident ray and the normal is called ________.<br>

Question 118 : Under which of the following conditions a concave mirror can form an image larger than the actual object?

Question 119 : The plane side of a plano-convex lens is silvered and the lens then acts as a concave mirror of $30$ cm focal length. The refractive lndex of the lens is $\displaystyle \frac{3}{2}$. Find the radius of the curvature of the lens.<br/>

Question 120 : A astronomical telescope has objective and eyepiece of focal lengths $40\ cm$ and $4\ cm$ respectively. To view an object $200\ cm$ away from the objective, the lenses must be separated by a distance:

Question 121 : A small object of linear dimension $x$ lies on the axis of an optical mirror of local length $f$ at a distance $a$ from mirror. The linear dimension of image:

Question 122 : An object is placed 30 cm away from a convex lens of focal length 10 cm and a sharp image is formed on a screen.Now a concave lens is placed in contact with the convex lens. The screen now has to be moved by 45 cm to get a sharp image again. The magnitude of focal length of the concave len is (in cm)

Question 123 : The radius of the sphere of which the reflecting surface of a spherical mirror forms a part, is called ...............

Question 124 : A short linear object of length $b$ lies along the axis of a concave mirror of focal length $f$ at a distance $u$ from the pole of the mirror. The size of the image is approximately equal to:<br/>

Question 125 : The distance between an object and its doubly magnified image by a concave mirror is: [ Assume $f$ = focal length]