Question 1 : Assertion: Rainy clouds appear dark from below. Reason: There is not sufficient light which can be scattered by these clouds.

Question 3 : When the length of a microscope tube increases, its magnifying power

Question 4 : How will the image formed by a convex lens be affected if thecentral portion of lens is wrapped in black paper ?

Question 5 : An object is placed first at infinity and then at $20\ cm$ from the object side focal plane of the convex lens. The two images thus formed are $5\ cm$ apart. The focal length of the lens is:

Question 6 : Which principle is the basis for the transmission of light through fiber optic cables even if the cable is bent?<br/>

Question 8 : A thin Plano convex lens acts like a concave mirror of focal length 0.2 m when silvered from its plane surface. The refractive index of the material of the lens is 1.5. the radius of curvature of the convex surface of the lens will be

Question 9 : The power of a lens is $+2.0D$. Find its focal length and state the kind of the lens.<br>

Question 11 : Two lenses of power - 15 D and +5D are incontact with each other. The focal length of thecombination is<br>

Question 12 : Which of the prism is used to see infrared spectrum of light

Question 13 : 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 14 : The angle between the two refracting surfaces of a total reflecting prism is :

Question 15 : State whether true or false:A concave lens forms a magnified or diminished image depending on the distance of object from it.<br/>

Question 16 : A ray of light suffers refraction throughequilateral prism. The deviation produced by theprism does not depend on the :

Question 17 : 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 18 : 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 23 : A ray of light travelling in air is incident on the plane of a transparent medium. The angle of incident is $45^0$ and that of refraction is $30^0$. The refractive index of the medium with respect to air is:

Question 25 : The power of a convex lens of focal length $2$ metre will be:

Question 26 : An astronaut in a spaceship the sky appears black due to:

Question 31 : A beam of parallel rays is brought to focus by a plano-convex lens. A thin concave lens of the same focal length is joined to the first lens. The effect of this is :

Question 32 : A man with normal near point $(25 \,cm)$ reads a book with small point using a magnifying glass, a thin convex lens of focal length $5 \,cm$.

Question 34 : The separation between two microscopic particles is measured $P_A$ and $P_B$ by two different lights of wavelength $2000\ A^o$ and $3000\ A^o$ respectively, then

Question 35 : In aerial mapping a camera uses a lens with a 100 cm focal length. The height at which the airplane must fly, so that the photograph of a 1 km long strip on the ground fits exactly on the 20 cm long filmstrip of the camera, is

Question 36 : The nature of image formed when an object is placed near to a concave lens is _____

Question 39 : Rainbow is formed in which direction with respect to the sun?

Question 40 : The magnification produced by the objective lens and the eye of a compound microscope are $25$ and $6$ respectively. The magnifying power of this microscope is

Question 41 : If a lens is cut into two pieces perpendicular to the principal axis and only one part is used, the intensity of the image

Question 42 : Which color should be used to increase the resolving power of a microscope

Question 43 : A ray of light incident on a lens parallel to its principal axis, after refraction passes through or appears to come from :

Question 45 : The time taken by sunlight to cross a $5\ mm$ thick glass plate $(\mu =3/2)$ is

Question 46 : How will the image formed by a convex lens be affected if the central portion of lens is wrapped in black paper?<br>

Question 47 : A plano-convex lens $(f=20\;cm)$ is silvered at plane surface. Now focal length will be :

Question 48 : Why is the focal point for any convex lens a little inexact with ordinary white light?

Question 49 : Which of the below is one of the laws of refraction?<br>

Question 51 : The focal length of a convex lens is $25cm$. Its power will be:

Question 52 : Absolute refractive indices of glass and water are $\dfrac {3}{2}$ and $\dfrac {4}{3}$. The ratio of velocity of light in glass and water will be

Question 53 : For the same statement as above, the ratio of the two image sizes for these two positions of the lens is<br>

Question 54 : The image of the needle placed 45 cm from a lens is formed on a screen placed 90 cm on the other side of the lens. The displacement of the image, if the needle is moved by 5.0 cm away from the lens is

Question 55 : The magnification produced by a mirror is $+\dfrac{1}{3}.$ Then the mirror is a ____________.

Question 56 : A concave lens and convex lens have same focal length of 16 cm each. They both are kept in contact. This combination is used to view an object 3.5 cm long, the image of this object is<br>

Question 57 : The focal length of an equiconvex lens is greater than the radius of curvature of any of the surfaces.Then the refractive index of the material of the lens is

Question 58 : A mark placed on the surface of a sphere is viewed through glass from a position directly opposite. If the diameter of the sphere is 10 cm and refractive index of glass is 1.5. The position of the image will be

Question 59 : A concave mirror is made from a hollow sphere of radius of curvature 30 cm. &#160;If an object of height 2 cm is placed at 10 cm from the pole of the mirror, determine the size of the image :

Question 60 : A vessel of water is $2 m$ deep. How deep will it appear if looked vertically downward?<br><br>$\displaystyle \left [_{a}{\mu }_{w} = \frac {4}{3} \right ]$

Question 61 : A convex lens of refractive index $1.5$ has a focal length of $18\ cm$ in air. Calculate its focal length when it is immersed in water of refractive index $\dfrac {4}{3}. take \&#160; f_1=18$.

Question 62 : Two lenses one of focal length $20 cm$. (convex lens)&#160;and another of focal length $-15 cm$ (concave lens) are&#160;placed in contact. Identify the correct statement.

Question 64 : A simple microscope is rated 5x for a normal relaxed eye. What will be its magnify power for a far sighted man whose near point is 40 cm?<br/>

Question 65 : An object is situated at a distance of 15cm from&#160;a convex lens of focal length 30 cm. The&#160;position of the image formed by it will be&#160;<br/>

Question 66 : A point object is placed at the center of a glass sphere of radius 6 cm and refractive index 1.5. The distance of virtual image from the surface is :<br/>

Question 67 : A $2 cm$ tall object is placed perpendicular to the principal axis of a convex lens of focal length $1 cm$. If the object distance is $1.5 cm$. Find the magnification.

Question 68 : A convex lens of focal length 50 cm, a concave lens of focal length 50 cm and another concave lens of focal lens 20 cm are placed in contact. The power of this combination in dioptres will be:

Question 69 : If $f_{1}$ and $f_{2}$ represent the first and second focal lengths of a single spherical refracting surface of refractive index $\mu $ then<br>

Question 70 : If two lenses of power + 1.5 D and +1.0 D are placed in contact, then the effective power of combination will be :

Question 71 : A ray of light passes from diamond to air. Critical angle is minimum for.

Question 72 : Assertion: If objective and eye lenses of a microscope are interchanged then it can work as telescope. Reason: The objective lens of telescope has small focal length.

Question 73 : An object is placed upright on the axis of a thin convex lens at a distance of four focal lengths ($4f$) from the center of the lens. An inverted image appears at a distance of $\dfrac{4}{3} f$ on the other side of the lens. What is the ratio of the height of the image of the height of the object?

Question 75 : A magnifying glass is to be used at the fixed object distance of $1$ inch. If it is to produce an erect image $5$ items magnified, its focal length should be-

Question 76 : An optical fibre is made of quartz filaments of refractiveindex 1. 70 and it has a coating of material whose refractiveindex is 1.45. The range of angle of incidence for one laserbeam to suffer total internal reflection is

Question 77 : Assertion: Farther the image greater is the magnification. Reason: Magnification is equal to the ratio of the distance of the object and that of the image.

Question 79 : Which of the following is responsible for the coin appearing shallower when it is kept at the bottom of a water tank?

Question 80 : The apparent flattening of the sun at sunset and sunrise is due to

Question 81 : A concave lens of glass, refractive index 1.5, has both surfaces of same radius of curvature R. On immersion in a medium of refractive index 1.75, it will behave as a :<br/>

Question 82 : Can light undergo total internal reflection at a smooth interface between air and water? If so, in which medium must it be traveling originally?

Question 83 : The illuminance of a surface is $10lux$. If the total area of the surface is $30 cm^{2}$, then the luminous flux incident on it will be&#160;

Question 84 : A lean boy named Ramesh placed a glass slab of refractive index $\dfrac{3}{2}$ on his photograph. He felt it more interesting as his face appeared bigger than the original size when observed from the top of the glass slab. He also observed that the photo appears at a height of $1.5$ cm from the bottom. He then placed another glass cube made of different material and having the same thickness over the first glass cube. Now, he himself started to laugh by seeing his photograph as it appeared still bigger than the previous. When observed from the top the photograph appears to be at a height of $4$ cm from the bottom. Determine the refractive index of the second glass cube.

Question 85 : A wire mesh consisting of very small squares is&#160;viewed at a distance of 8 cm through a&#160;magnifying converging lens of focal length 10&#160;cm, kept close to the eye. The magnification&#160;produced by the lens is.

Question 86 : Why do we see a rainbow in the sky only after rainfall?<br/>

Question 87 : In case of refraction of light<br/>a) Frequency changes <br/>b) Speed changes <br/>c) Wavelength changes<br/>

Question 88 : Two plano convex lenses of same material and of focal lengths 20 cm &amp; 5 cm should be arranged such that the combination is free from chromatic aberration. Then effective focal length of the combination will be:

Question 89 : An object is placed at a distance of $10 \ cm$ from a co-axial combination of two lenses $A$ and $B$ in contact. The combination forms a real image three times the size of the object. If lens $B$ is concave with a focal length of $30 \ cm$, what is the nature and focal length of lens $A$ ?

Question 90 : When a glass prism of refracting angle ${60}^{o}$ is immersed in a liquid its angle of minimum deviation is ${30}^{o}$. The critical angle of glass with respect to the liquid medium is:

Question 91 : In good-quality microscopes, lens combinations are used for the objective and eyepiece instead of single lenses.

Question 92 : The image of an object formed by a concave lens is:

Question 94 : If $m$ compound microscope $m_{1}$ and $m_{2}$ be the linear magnification of the objective lens and eye lens respectively, then magnifying power of the compound microscope will be

Question 95 : A narrow white light beam fails to converge at a point after going through a converging lens. This defect is known as :

Question 96 : A prism of refractive index $\sqrt 2 $ has refracting angle ${60^ \circ }$ answer the question<br>Angle of minimum deviation is:

Question 97 : A source of light emits a continuous stream of light energy which falls on a given area. Luminous intensity is defined as

Question 98 : A lens behaves as a converging lens in air and a diverging lens in water $ \left( \mu =1.33 \right) $. The refractive index of the material is <br/>

Question 99 : The human eye can be regarded as a single spherical refractive surface of curvature of cornea 7.8mm. If a parallel beam of light comes to focus at 3.075 cm behind the refractive surface, the refractive index of the eye is

Question 100 : An object $5$ cm tall is placed $1$ m from a concavespherical mirror which has a radius of curvatureof $20$ cm. The size of the image is:<br>

Question 101 : When the object is placed 4 cm from the objective of microscope, the final image formed coincides with the object. The final image is at the least distance of distinct vision (24 cm). If the focal length of eye piece is 8 cm then the focal length of objective is

Question 102 : Image of an object at infinity is formed by a convex lens of focal length $30 \ cm$ such that the size of the image is $2 \ cm$. If a concave lens of focal length $20\&#160; cm$ is placed in between the convex lens and the image, at a distance $26\&#160; cm$ from the convex lens, size of the new image is:

Question 103 : <br>Concave and convex lenses, each have the same focal length $20 cm$ and they are put in contact to form a combination lens. This combination lens is used to view an object of $5 cm$ length, kept at a distance $20 cm$ from the lens combination. As compared to the object the image will be<br>

Question 104 : Two glass prisms $P_1$ and $P_2$ are to be combined together to produce dispersion without deviation. The angles of the prisms $P_1$ and $P_2$ are selected as $4^o$ and $3^o$ respectively. If the refractive index of prism $P_1$ is 1.54, then that of $P_2$ will be

Question 105 : A compound microscope has on objective of focal length 0.5 cm and a tube length of 15 cm. If it produces and angular magnification of 225 in normal adjustment, find the focal length of the eyepiece.

Question 106 : An object 2 cm high is placed at a distance of 16 cm from a concave mirror, which produces a real image 3 cm high. What is the focal length of the mirror?

Question 107 : 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 108 : A thin prism $P_1$ with angle $6^o$ and made from glass of refractive index 1.54 is combined withanother thin prism $P_2$ of refractive index 1.72 toproduce dispersion without deviation. The angleof prism $P_2$ will be.

Question 109 : A motor car is fitted with a convex driving mirror of focal length 20cm. A second motor car 2.8m behind the first car is overtaking speed of 15 $ { ms }^{ -1 }$. The speed of the image of the second car as seen in the mirror of the first is&#160; :

Question 110 : A thin lens of focal length f has a diameter d of its aperture and forms an image of intensity &#160;I. Now the central part of the aperture up to a diameter&#160;$\dfrac{d}{2}$ is blocked by white paper. Then&#160;

Question 111 : The maximum distance from real object to a real image in a concave mirror is&#160;

Question 112 : The magnitude of focal length of a concave mirror is $f$. An object is placed at a distance $x$ from the focus and forms a real image. The magnification is:<br/>

Question 113 : A thin converging lens of focal length $f=25\ cm$ forms the image of an object on a screen placed at a distance of $75\ cm$ from the lens. The screen is moved closer to the lens by a distance of $25\ cm$. The distance through which the object has to be shifted so that its image on the screen is sharp again is:<br/>

Question 114 : Two identical glass ($\mu_e=3/2$) lenses of focal length f each keeps in contact. The space between the two lenses is filled with water ($\mu_w=4/3$). The focal length of the combination is.

Question 116 : A double convex lens of focal length $20 cm$ is made of glass $\displaystyle \mu=\frac{3}{2}$. What will be lts focal length when lmmersed in a liquid of $\displaystyle \mu=\frac{4}{3}$?<br>

Question 117 : Two plane mirror are lying perpendicular to each other, there is lamp in between mirrors. Then number of images of lamp will be

Question 118 : Distance between focus and optical centre of a lens is called ....................

Question 119 : A convex lens has its radii of curvature equal. The focal length of the lens is f. If it is divided vertically into two identical plano-convex lenses by cutting it, then the focal length of the plano-convex lens is:[$\mu-$ the refractive index of the material of the lens]<br/>

Question 120 : <br/>A convex lens made of glass of $\mu=1.5$ has a focal length $f$ in air. When it is completely immersed in a liquid of $\mu$ $=2$ its focal length and nature will be:<br/>

Question 121 : A thin prism of glass is placed in air and water successively. If $_{a}\mu_{g}=3/2$ and $_{a}\mu_{w}=4/3$, then the ratio of deviations produced by the prism for a small angle of incidence when placed in air and water is:

Question 122 : A plano-convex lens fits exactly into a plano-concave lens. Their plane surfaces are parallel to each other. If the lenses are made of different material of refractive indices $\mu_{1}$ and $\mu_{2}$ and $R$ is the radius of curvature of the curvature of the curved surface of the lenses, then focal length of the combination is

Question 124 : A converging lens of focal length $f_1$ is placed in front of and coaxially with a convex mirror of focal length $f_2$. Their separation is d and whole arrangement is in air. A parallel beam of light incident on the lens returns as a parallel beam from the arrangement.<br>

Question 125 : There is an equiconvex glass lens with radius of each face as $R$ and $_a\mu_{g}=3/2$ and $_a\mu_w =4/3$. If there is water in object space and air in image space, then the focal length is

Question 126 : A convex glass lens $\left( { \mu&#160; }_{ g }=1.5 \right)$ has a focal length of 8 cm when placed in air. What is the focal length lens when it is immersed in water? $\left( { \mu&#160; }_{ \omega&#160; }=\dfrac { 4 }{ 3 }&#160; \right) $

Question 127 : A concave mirror has a focal length of $20\ cm$. The distance between the two positions of the object for which the image size is double of the object size is

Question 128 : The objective and eyepiece of an astronomical telescope are doubled convex lenses with refractive index $1.5$. When the telescope is adjusted to infinity, the separation between the two lenses is $16\ cm$. If the space between the lenses is now filled with water and again telescope is adjusted for infinity, then the present separation between the lenses is:

Question 129 : 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 130 : 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 131 : 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 133 : There is an equiconvex lens of focal length of $20 &#160; cm$. If the lens is cut into tow equal parts perpendicular to the optical axis, the focal length of each part will be

Question 134 : The convex side of a thin plano-convex lens with radius of curvature 60 cm is silvered to obtain a concave mirror. An object is located at a distance of 30 cm in front of this mirror. The distance of the image from the mirror is ($\mu$= 1.5)

Question 135 : Under which of the following conditions a concave mirror can form an image larger than the actual object?

Question 136 : 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 137 : In optical fiber, refractive index of inner part is $1.68$ and refractive index of outer part is $1.44$. The numerical aperture of the fibre is

Question 138 : What happens when a ray of light is made to fall on a mirror along the normal?<br/>

Question 139 : The objective lens of a compound microscope produces magnification of $10$. In order to get an overall magnification of $100$ when image is formed at $25cm$ from the eye, the focal length of the eye lens should be :(in $cm$)

Question 140 : A ray of light passes through an equilateral prism such that the angle of incidence is equal to the angle of emergence and the latter is equal to $\displaystyle {\frac{3}{4}}^{th}$ angle of prism. What will be the deviation?<br>

Question 141 : A 35 mm film is to be projected on a 20 m wide screen situated at a distance of 40 m from the film projector. Calculate the distance of the film from the projection lens and focal length of projection lens.

Question 142 : 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 143 : When the object is at distance $u_{1}$ and&#160; $u_{2}$ from a lens, a real image and virtual image are formed respectively having the same magnification. The focal length of the lens is :

Question 144 : The plane side of a thin plano-convex lens with radius of curvature 20 cm is silvered to obtain a concave mirror. An object is located at a distance of&#160;25 cm in front of this mirror. The distance of the image from the mirror is($\mu=$ 1.5)

Question 145 : Assertion: Although the surface of goggles' lens is curved, it does not have any optical power. Reason: &#160;In case of goggles, both the curved surfaces have equal radii of curvature and have centre of curvature on the same side.

Question 146 : A convex lens forms a real image with magnification $m_{1}$ on a screen.Now,the screen is moved by a distance x and the object is also moved &#160;so as to obtain a real image with magnification $m_{2}(&gt;m_{1})$ on the screen.Then,the&#160;focal length of the lens is<br/>

Question 147 : A lens forms a real image of an object on a screen placed at a distance of 100 cm from the screen. If the lens is moved by 20 cm towards the screen, another image of the object is formed on the screen. The focal length of the lens is:

Question 148 : The nature of image of a candle flame located $40$cm from a concave spherical mirror is real, inverted and magnified four times. Then the radius of curvature of the mirror is:

Question 149 : A converging lens of focal length 30 cm and diverging lens of focal length 20 cm are kept 15 cm apart with their principal axes coinciding. Where shall an object be placed to form an image at infinity?<br/>

Question 150 : 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: