Question 1 : Find the focal length of a convex lens, if its power is +2.0 D.

Question 3 : 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 4 : By which optical phenomena the splitting of white light into seven constituent colours occur?<br>

Question 5 : If the wavelength of the light be $\lambda$, the wavelength in a medium of refractive index $n$ will be

Question 6 : <p>An object is placed at a<br><br>distance of 5 cmmore than the focal length$f$ of a convex lens. Its real image is formedat a distance$3f$ beyond the focus .The focal length$f$ of the<br><br>lens is:</p>

Question 7 : A thin lens is made with a material having refractive index $1.2$. Both the surfaces of the lens are convex. It is dipped in water$(\mu = 1.33)$. It will behavelike

Question 8 : According to Snell's Law of refraction, the ratio of the refractive index is related to the inverse ratio of the ____ of the angles.<br/>

Question 9 : If you are to determine the the focal length of a convex lens, you should have:

Question 10 : If eyepiece lens of a compound microscope is moved a little away from objective lens without changing positions of object and objective lens, then

Question 11 : A ray of light is incident normally on a plane glass slab. What will be the angle of refraction ?

Question 12 : Three lenses have a combined power of $2.7 D$. If the powers of two lenses are $2.5 D$ and $1.7 D$ respectively, find the focal length of the third lens.

Question 13 : A solid transparent sphere has a small opaque dot at its centre. When observed from outside, the apparent position of the dot will be

Question 14 : Assertion: There exist two angles of incidence for the same magnitude of deviation (except minimum deviation) by a prism kept in the air. <br/>Reason: In a prism kept in the air, a ray is incident on the first surface and emerges out of the second surface. Now if another ray is incident on second. surface (of the prism) along the previous emergent ray, then this ray emerges out of the first surface along the previous incident ray. This principle is called the principle of reversibility of light.

Question 16 : 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 17 : If the power of a lens is $0.1\;D$, its focal length is

Question 18 : Intensity of refracted ray of light will be ________ than that of the incident light. Fill in the blank.&#160;

Question 19 : When a ray of light&#160;traveling in a (A) Medium, is incident at the surface of a (B) Medium such that angle if incidence is (C) than the critical angle for&#160;the pair of media, the ray is totally reflected back into the (D) medium. This phenomenon is called total internal reflection.

Question 20 : If a convex lens is dipped in a liquid whose&#160;refractive index is equal to the refractive index of&#160;the lens, then lens acts like a<br/>

Question 22 : 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 : The angle of minimum deviation measured with a prism is $30^o$ and the angle of prism $60^o$. The refractive index of prism material is -

Question 25 : When the length of a microscope tube increases, its magnifying power

Question 26 : A real image occurs when rays converge. A virtual image occurs when rays

Question 27 : The equiconvex lens has a focal length 'f'. If the lens is cut along the line perpendicular to principal axis and passing through the pole, what will be the focal length of any half part?

Question 28 : Assertion: Rainy clouds appear dark from below. Reason: There is not sufficient light which can be scattered by these clouds.

Question 29 : The rays of different colors fail to converge at a point after going through a converging lens. This defect is called _________.

Question 30 : Light enters from denser to rarer medium. Choose the correct option.

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 : When the height of the image is less than the height of the object, then magnification will be

Question 34 : Assertion: Critical angle of light passing from glass to air is minimum for violet color. Reason: The wavelength of blue light is greatest to the light of other colors.

Question 35 : For which of the following colour, the magnifying power of a microscope will be maximum

Question 36 : In a plano-convex lens the radius of curvature of the convex lens is $10\ cm$. If the plane side is polished then the focal length will be (Refractive index $=1.5$)

Question 37 : The bending of light ray after passing through a medium is commonly known as :

Question 38 : If the refractive index of medium $b$ with respect to medium $a$ and that of medium $c$ with respect to medium b are given, then the refractive index of a medium $c$ with respect to a medium $a$ can be found by using the relation<br/>$n_{ca}\, =\, n_{ba}\, \times\, ........$<br/><br/>

Question 39 : 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 40 : Power of a lens is $-4$D and for second lens power is $+2$D; the total power of the couple.

Question 41 : Match the items given in A, B, C and D against their corresponding description given in 1, 2, 3, 4 and 5.<br>A. Astronomical telescope<br>B. Galilean Telescope<br>C. Simple Microscope<br>D. Compound Microscope<br><br>1. Contains one convex lens<br>2. Contains one concave lens<br>3. Contains a convex lens of large focal length in the objective and a convex lens of small focal length in the eye-piece<br>4. Contains a convex lens of small focal length in the objective and a convex lens of large focal length in the eye-piece<br>5. Contains a convex lens of large focal length in the objective and a concave lens of small focal length in the eye-piece.

Question 42 : When the length of a microscope tube increases, its magnifying power

Question 43 : Light from a lamp is falling normally on a surface distant $10$ m from the lamp and the luminous intensity on it is $10$lux. In order to increase the intensity $9$ times, the surface will have to be placed at a distance of&#160;

Question 44 : The one parameter that determines the brightness of a light source sensed by an eye is <br>

Question 45 : Two thin lenses of focal lengths $20cm$ and $25cm$ are placed in contact. The effective power of the combination is

Question 46 : A convex lens forms an image of an object placed $20 cm$ away from it at a distance of $20 cm$ on the other side of the lens. If the object moves $5 cm$ towards the lens, then the image will be :<br/>

Question 47 : A fish is a little away below the surface of a table. If the critical angle is $49^o$, then the fish could see things above the water surface within an angular angle of

Question 48 : A convex lens of power $+6$ dioptre is placed in contact with a concave lens of power $-4$ dioptres. What will be the nature and focal length of this combination?<br>

Question 49 : Assertion: The resolving power of both microscope and telescope depends on the wavelength of light used. Reason: The resolving power of a lens is the ability to resolve the two images so they are distinctly identified.

Question 50 : A beam of light propagation in medium $A$ with index of refraction $n$ $(A)$ passes across an interface into medium $B$ with index of refraction $n(B)$. The angle of incident is greater than the angle of refraction; $v(A)$ and $v(B)$ denotes the speed of light in $A$ and $B$. Then which of the following is true

Question 51 : The lateral shift produced by a glass slab increase with&#160;_________ in the thickness of the glass slab.

Question 52 : If in a plano-convex lens, the radius of curvature of the convex surface is $10cm$ and the focal length of the lens is $30cm$, then the refractive index of the material fo lens will be

Question 53 : The least distance of vision of a longsighted person is $60\ cm$. By using a spectacle lens, this distance is reduced to $12\ cm$. The power of the lens is

Question 54 : If linear magnification for a spherical mirror is $\dfrac{3}{2}$, then we may write:&#160;(symbols have their usual&#160;meanings)&#160;

Question 55 : The dispersive power of crown and flint glasses are $0.02$ and $0.04$, respectively. An achromatic converging lens of focal length $40\ cm$ is made by keeping two lenses, one of crown glass and the other of flint glass, in contact with each other. The focal lengths of the two lenses are

Question 56 : 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 57 : The radius of curvature of a thin plano convex lens&#160;is 10 cm and the refractive index of its glass is 1.5. If the plane surface is silvered , then it will&#160;behave like a :<br/>

Question 58 : The focal length of the objective lens of a compound microscope is

Question 59 : A thin oil layer floats on water. A ray of light&#160;making an angle of incidence 40$^o$ shines an oil&#160;layer. The angle of refraction of Iight ray in water is $(mu_{oil} = 1.45, \mu_{water} = 1.33)$<br/>$[sin &#160;40^o = 0.6428, sin 44.5^o = 0.7007]$

Question 60 : 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 61 : The plano-convex lens of focal length $20$cm and $30$cm are placed together to form a double convex lens, the final focal length will be :

Question 62 : When the plane surface of a plano-convex lens of refractive index $1.5$ is silvered, it behaves like a concave mirror with $f=30\ cm$.When its convex surface is silvered, it will behave like a concave mirror of focal length:

Question 63 : A biconvex lens is made of material of refractive index 1.5 each of radius of curvature of lens surface is 20 cm. The focal length of lens is:

Question 64 : 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 65 : Consider the following statements:<br>(a) Light bends from its path, when it goes from one medium to another medium<br>(b) Speed of light changes, when it goes from one medium to another medium<br>(c) Wavelength of light decreases, when it travels from air to water<br>(d) Wavelength of light in water $=\displaystyle\frac{Wavelength of light in air}{Refractive index of water}$<br>Which of the above statements are correct?

Question 66 : The length of the tube of a microscope is $10\ cm$.The lengths of the objective and eye lenses are $0.5\ cm$and $1\ cm$respectively. The magnifyingpower of the microscope when the images at farpoint is about

Question 67 : Assertion: The edges of the images of white object formed by a concave mirror on the screen appear white. Reason: Concave mirror does not suffer chromatic aberration.

Question 68 : Focal length of a convex lens is 10 cm. When the object is moved from 15 cm to 25 cm, the magnitude of linear magnification

Question 69 : A source emits $31.4$ $W$ of radiant flux distributed uniformly in all directions. The luminous efficiency is $60\ lumen/W$. Find the luminous intensity of the source.

Question 70 : A convex lens form a real image of a point object placed on its principal axis. if the upper half of the lens is painted black,<br>

Question 71 : 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 72 : A thin lens has focal length f, and its aperature has diameter d It forms an image of intensity I. Now the central part of the apearture upto diameter d/2 is blocked by an opaque paper. The focal length and image intensity will change to the :<br/>

Question 73 : A thin equiconvex glass lens of refractive index $1.5$ has power of $5D$. When the lens is immersed in a liquid of refractive index $\mu$, it acts as a divergent lens of focal length $100 \,cm$. The value of $\mu$ of liquid is

Question 74 : A prism $( \mu = 1.5)$ has the refracting angle of&#160;$60^o$. The deviation of a monochromatic ray incident normally on its one&#160;surface will be $(sin 48^o 36' = 0.75)$<br/>

Question 75 : A bird flying above a pond starts moving vertically down towards the water below at a speed of $v \ m &#160;s^{-1}$. Find its apparent velocity as viewed by a fish located at a depth of $d$ m below&#160;the surface of water of refractive index&#160;$\mu $.

Question 76 : 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 77 : A circular area of radius $1\ cm$ is placed $2\ m$ away from a point source. The source emits light uniformly in all directions. The source is on the line of the normal from the centre of the area. $2\times10^{-3} $luminous flux is incident on the area. Find the total flux emitted by the source.

Question 78 : A planoconvex lens fits exactly into a planoconcave lens. Their plane surface are parallel to each other. If the lenses are made of different materials of refractive indices $\mu_{1}$ and $\mu_{2}$ and $R$ is the radius of curvature of the curved surface of the lenses, then focal length of combination is

Question 79 : The process of re-emission of absorbed light in all directions with different intensities by the atom or molecule is called ____________.

Question 80 : 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 81 : The sun's diameter is $1.4 \times { 10 }^{ 9 }m$ and its distance from the earth is ${ 10 }^{ 11 }m$. Determine the diameter of its image, formed by a convex lens of focal length $2\ m$.

Question 82 : An object is kept at a distance of $16\ cm$ from a thin lens and the image formed is real. If the object is kept at a distance of $6\ cm$ from the same lens, the image formed is virtual. If the sizes, of the images formed are equal, the focal length of the lens will be

Question 83 : The focal length of a convex lens of refractive index $1.5$ is $f$ when it is places in air. When it is immersed in a liquid it behaves as a converging lens its focal length becomes $xf(x&gt;1)$. The refractive index of the liquid

Question 84 : &#160;If light falls on the surface at an angle of $60^{0}$, then illuminance will be____

Question 85 : 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 86 : <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 87 : A plano-convex lens, when silvered at its plane surface is equivalent to a concave mirror of focal length 28 cm. When its curved surface is silvered and the plane surface is not silvered, it is equivalent to a concave mirror of focal length 10 cm, then the refractive index of the material of the lens is :

Question 88 : The angle of minimum deviation for a ${75^ \circ }$ prism of dense glass is found to be ${45^ \circ }$ when in air and ${15^ \circ }$ when immersed in certain liquid. The refractive index of the liquid is :

Question 89 : An object of height $4$ cm is placed at a distance of $15 cm$ in front of a concave lens of power, $-10$ dioptres. Find the size of the image.

Question 90 : When a light of wavelength $4000$ $\displaystyle \overset { \circ &#160;}{ A }&#160;$ in vacuum travels through the same thickness in diamond and water separately, the difference in the number of waves is $200$. Find the thickness, if refractive indices of diamond and water are&#160;$\displaystyle \frac { 5 }{ 2 }&#160;$ and&#160;$\displaystyle \frac { 4 }{ 3 }&#160;$ respectively.

Question 91 : When a beam of white light parallel to the principal axis is refracted through a convex lens, then the rays converge to the principal axis. If a screen is placed at a sufficient distance from the focus-point perpendicular to the principal axis then the image on the screen will be.

Question 92 : The radius of the sphere of which the reflecting surface of a spherical mirror forms a part, is called ...............

Question 93 : 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 94 : 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 95 : A thin plano - convex lens fits exactly into a thin plano - concave lens. Their plane surfaces are parallel to each other. If the lenses are made of different materials of refractive indices $\mu _{1}$ and $\mu _{2}$ and R is the radius of curvature of the curved surfaces of the lenses, then the focal length of the combination is :<br/>

Question 96 : A cubical room is formed with $6$ plane mirror. An insect moves along diagonal of the floor with uniform speed. The velocity of its image in two adjacent walls are $20\sqrt 2 $ cm/s. Then the velocity of image formed by the roof is ;

Question 97 : In displacement method, the distance between object and screen is $96\ cm$. The ratio of lengths of two images formed by a converging lens placed between them is $4$. Then

Question 98 : 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 99 : The apparent depth of water in cylindrical water tank of diameter $2 R$ cm is reducing at the rate of $x\ cm/minute$ when water is being drained out at a constant rate. The amount of water drained in c.c, per minute is : ( $\displaystyle { n }_{ 1 }$&#160;= refractive index of air,&#160;$\displaystyle { n }_{ 2 }$&#160;&#160;= refractive index of water)

Question 100 : If a lens of focal length, $f$, made of glass of refractive index $ \dfrac { 5 }{ 3}$ is placed in a liquid of refractive index, $4\ \dfrac { 5 }{ 3 } $, then the focal length of the lens becomes<br/>