Question 1 :
A person uses spectacles of power $+2\ D$. He is suffering from
Question 2 :
Optical fibres transmit light along its axis, by the process of :
Question 3 :
The maximum magnification that can be obtained with a convex lens of focal length $2.5\ cm$ is ( the least distance of distinct vision is $25\ cm$)
Question 5 :
Two thin lenses of focal lengths $f_{1} and f_{2}$ are in contact and coaxial. The power of the combination is :<br/>
Question 6 :
Two thin lenses whose powers are $+2D$ and $-4D$ respectively combine, then the power of combination is
Question 8 :
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 9 :
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 10 :
Calculate the focal length of a convex mirror of radius of curvature 20 cm. <br/>
Question 12 :
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  made by the light ray with the normal in each, greatest first.
Question 13 :
A point object is placed at the centre of a glass sphere of radius $6\ cm$ and refractive index $1.5.$ The distance of virtual image from the surface is:
Question 14 :
A ray of light suffers refraction throughequilateral prism. The deviation produced by theprism does not depend on the :
Question 16 :
The rays of different colors fail to converge at a point after going through a converging lens. This defect is called _________.
Question 17 :
Why are red coloured lights are used in traffic signals to stop the vehicles?
Question 18 :
What are the colours of the Sun observed most during sunrise/sunset and noon? <br/>
Question 19 :
A convex lens is used to form real image of an object on a screen. It is observed that even when the positions of the object and that screen are fixed are two position of the lens to form real images. If the heights of the images are $4\ cm$ and $9\ cm$ respectively the height of the object is
Question 20 :
When light is refracted from a surface, which of its following physical parameters does not change?
Question 21 :
A symmetric double convex lens is cut in two equal parts by a plane perpendicular to the principal axis. If the power of the original lens is $4 D$, the power of cut lens will be ________.
Question 22 :
A tank is filled with benzene to a height of $120\ mm$. The apparent depth of a needle lying at a bottom of the tank is measured by a microscope to be $80\ mm$. The refractive index of benzene is
Question 24 :
Two thin lenses of focal; lengths $f_1$ and $f_2$ are in contact and coaxial. The combination is equivalent to a single lens of power
Question 25 :
A fist looking from within water sees the outside world through a circular horizon. If the fist $\sqrt 7cm$ below the surface of water, what will be the radius of the circular horizon
Question 28 :
The second law of refraction is also named after its discoverer as :
Question 29 :
The radius of curvature of the convex surface ofa thin plane convex lens is 15cm and therefractive index of its material is 1. 6. The powerof the lens is will be-<br>
Question 30 :
A printed page is seen through a glass slab place on it. The printed words appear raised. This is due to:
Question 32 :
There is a small black dot at the centre C of a solid glass sphere of refractive index $\mu$. When seen from outside, the dot will appear to be located:
Question 34 :
The bluish colour of water in deep sea is due to:<br/>
Question 35 :
If the power of a lens is $0.1\;D$, its focal length is
Question 37 :
A wave has velocity v in medium P and velocity 2v in medium Q. If the wave is incident in medium P at an angle of 30, then the angle of refraction will be
Question 38 :
Two thin lenses of powers 2D and 3D are placed in contact. An object is placed at a distance of 30 cm from the combination. The distance (in cm) of the image from the combination is :<br/>
Question 39 :
A concave mirror and aconverging glass with $(\mu =1.5)$ both have a focal length of $3cm $ when in air. When they are in water $\left(\mu =\dfrac{4}{3}\right)$ their new focal lengths are
Question 40 :
Change in the direction of light when it passes from one medium to another is called ............
Question 41 :
It is first face of a prism which disperses white light. The statement is
Question 42 :
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 46 :
The apparent vertical shift of the image of a coin placed at the bottom of a water tank having constant depth of water is proportional to (given refractive index of water =$\mu$).
Question 47 :
For which of the following colour, the magnifying power of a microscope will be maximum
Question 48 :
If you are to determine the the focal length of a convex lens, you should have:
Question 50 :
A ray of light is incident normally on a plane glass slab. What will be the angle of refraction ?
Question 51 :
Assertion: Optical fibres are used for telecommunication.
Reason: Optical fibres are based on the phenomenon of total internal reflection.
Question 52 :
The angle of a prism is $6^0$ and its refractive index for green light is 1.5. If a green ray passes through it, the deviation will be :-
Question 53 :
An object is placed at a distance of $10 cm $ from the concave mirror and the image is formed  $20 cm $ in front of the mirror. The focal length of the mirror is:
Question 54 :
An object is situated at a distance of 15cm from a convex lens of focal length 30 cm. The position of the image formed by it will be <br/>
Question 55 :
A slide projector is to project a $(35 mm \times  23 mm)$ slide on a $2m \times 2m$ screen. Find the focal length of the lens used if screen is 10 m away from the lens.<br/>
Question 56 :
An object is at $0.06$ m from a convex lens of focal length $0.10$m. Find the position of the image.
Question 58 :
A compound microscope has an objective of focallength 1 cm and an eyepiece of 4 cm. If the tube lengthis 20 cm. Then the magnification of the compoundmicroscope is : (final image is at D )
Question 59 :
Two thin biconvex lenses $L_{1}$ and $L_{2}$ having focal lengths 10 cm and 15 cmrespectively are placed coaxially.What distance (d) should be maintained between them so that aparallel beam of light parallel beam of light parallel to their axis, incident on the lens $L_{1}$ emerges from $L_{2}$ undeviated? If the distance between them is increased by 'd' atwhat distance from $L_{1}$, on the axis, does the emergent beam converge?
Question 60 :
Consider telecommunication through optical fibres. Which of the following statements is not true?
Question 61 :
A plano concex lens is made of material having refractive index 1.5.The radius of curvature of the curved surface is is 20 cm.How far away from its optical center will the image be formed if the object is at infinity?
Question 62 :
Assertion: A biconvex lens of focal length 10 cm is split into two equal parts by a plane parallel to its principle axis.The focal length of each part will be 20 cm.
Reason: Focal length depends on the radii of curvature of two surfaces.
Question 63 :
If the radius of curvature of the curved surface of a planoconvex lens is $50cm$, its focal length is $(\mu =1.5)$
Question 64 :
For which of the two lenses $L_1$ and $L_2$ the chromatic aberration will be more if the radii of curvature of the surfaces of $L_1$ are less than those of $L_2$:
Question 65 :
A candle is placed $20\ cm$ from the surface of a convex mirror and a plane mirror is also placed so that the virtual images in the two mirrors coincide. If the plane mirror is $12\ cm$ away from the object, what is the focal length of the convex mirror?
Question 66 :
A convex lens of focal length 0.2 m and made of glass $(^a \mu_g = 1.5)$ is immersed in water $(^a \mu_w = 1.33)$. Find the change in the focal length of the lens.
Question 67 :
A mark is made on the surface of a glass sphere of diameter $10 cm$ and refractive index $1.5$. It is viewed through the glass from a portion directly opposite. The distance of the image of the mark from the center of the sphere will be
Question 68 :
A glass lens is placed in a medium in which it is found to behave like a glass plate$.$ Refractive index of the medium will be
Question 69 :
A convex lens of focal length $20cm$ is placed in contact with a concave lens of focal length $10cm.$ calculate power of combination. 
Question 70 :
Two lamps of luminous intensity of $8$ $Cd$ and $32$ $Cd$ respectively are lying at a distance of $1.2$ $m$ from each other. Where should a screen be placed between two lamps such that its two faces are equally illuminated due to the two sources?
Question 71 :
If the image is real then the distance of the image can be given as ;
Question 72 :
One surface of a lens is convex and the other is concave. If the radii of curvatures are $R_1$ and $R_2$, then the lens Will be convex, if :<br/>
Question 74 :
The luminous flux of a $60$ $W$ power bulb is $600$ lumen. The luminous efficiency of the bulb will be :
Question 75 :
Assertion: A reflecting type telescope is preferred astronomy.
Reason: Weight of the mirrors are less as compared the lenses.
Question 76 :
A thin convergent glass lens $\mu  =$1.5 has a power of $+5D$. When this lens is immersed in a liquid of refractive index $\mu $  it acts as a diverging lens of focal length 100 cm. The value of $\mu $  must be :<br/>
Question 77 :
Two convex lenses of focal lengths $f_{1}$ and $f_{2}$ form images with magnification $m_{1}$ and $m_{2}$, when used individually for an object kept at the same distance from the lenses. Then $f_{1}/f_{2}$ is:
Question 78 :
A convergent beam of light converges to a point 20 cm behind a concave lens on the principal axis. An inverted image of the same size is formed. An inverted image of the same size is formed. Then the focal length of the lens is then<br/>
Question 79 :
A mark on the surface of a glass sphere($\mu =$1.5) is viewed from a diametrically opposite position. It appears to be at a distance 10 cm from its actual position. The radius of sphere is:<br>
Question 80 :
The far point of a person suffering from myopia is 2 metres from the eye. Find the focal length and power of the corrective lens that will correct his vision.
Question 81 :
A thin bi-convex lens (n=1.5 ) has a focal length of 50 cm in air.When immersed in a transparent liquid , the focal length is measured to be 250 cm.The refractive index of the liquid medium is
Question 82 :
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 83 :
A lens is made of flint glass (refractive index = 1.5). When the lens is immersed in a liquid of refractive index 1.25, the focal length :
Question 84 :
A double convex lens of focal length 15 cm is to be used as a magnifying glass. In order to produce an erect image which is 3 times magnified, the distance between the object and the lens should be
Question 85 :
Light travels in two media A and B with speeds $1.8 \times { 10 }^{ 8 } m { s }^{ -1 }$ and $ 2.4 \times { 10 }^{ 8 } m { s }^{ -1 } $ respectively. Then the critical angle between them is
Question 87 :
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 88 :
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 89 :
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 90 :
Two thin lenses, when in contact, produce a combined power +10 dioptre. When they are 0.25 m apart, the power reduce to +6 dioptre. The power of the lenses in dioptre, are:<br/>
Question 91 :
 If light falls on the surface at an angle of $60^{0}$, then illuminance will be____
Question 92 :
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 93 :
A biconvex lens of focal length 15 cm is in front of a plane mirror. The distance between the lens and the mirror is 10 cm. A small object is kept at a distance of 30 cm from the lens. The final image is :<br/>
Question 94 :
A glass slab of thickness 18 cm and refractive index$\dfrac{3}{2}$ is placed on a printed matter. The normal shift of the printed matter is
Question 95 :
Distance between focus and optical centre of a lens is called ....................
Question 96 :
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 97 :
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 98 :
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 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 : ( $\displaystyle { n }_{ 1 }$ = refractive index of air, $\displaystyle { n }_{ 2 }$  = refractive index of water)
Question 100 :
A $2.5$ dioptre lens forms a virtual image which is $4$ times the object placed perpendicularly on the lens. Then the required distance of the object from the lens is .
