Question 2 : In the white light of sun, maximum scattering by the air molecules present in the earth's atmosphere is for:<br>

Question 4 : Which of the following phenomena contributes significantly to the&#160;reddish appearance of the sun at sunrise or sunset?<br/>

Question 5 : Which of the following phenomena contributes significantly to the&#160;reddish appearance of the sun at sunrise or sunset?<br/>

Question 6 : Fine beam of light entering through a small hole in a dark room illuminates the particles in its path. Identify the effect associated with this process.<br/>

Question 7 : The inability among the elderly to see nearby objects clearly because of the weaking of the ciliary muscles is called

Question 8 : When white light is passed through two consecutive prisms, the resultant will be:

Question 10 : A prism is a piece of transparent material having _____ triangular and _____ rectangular surfaces.

Question 11 : Why astronauts see dark sky in space unlike blue sky on earth:

Question 12 : The rising and setting of sun appear red because of :&#160;

Question 13 : At which place in eye,image is formed of a person is far-sightedness (hypermetropia) ?

Question 15 : When a white light ray falls on a prism, the ray at its first surface suffers:<br>

Question 16 : For the myopic eye, the far point is farther away than the normal.

Question 19 : Assertion: A beam of white light gives a spectrum on passing through a hollow prism. Reason: Speed of light outside the prism is different from the speed of light inside the prism.

Question 20 : In context of scatteringFine particles : ____ wavelength : : large particles : _____ wavelength

Question 21 : An astronaut in a spaceship the sky appears black due to:

Question 22 : The color of scattered light depends on ____ of the scattering particles.

Question 25 : Which colour of light is scattered the most(maximum) in the atmosphere?

Question 27 : The path of a beam of light is invisible in which solution?

Question 29 : The bluish colour of water in deep sea is due to:<br/>

Question 30 : The least distance of distinct vision for a defective eye is $75$ cm. What should be the focal length of the lens which will be used to read a book clearly at $25$ cm?

Question 31 : The bluish colour of water in deep sea is due to:<br/>

Question 32 : Name the prism required for obtaining the spectrum of ultraviolet light:<br/>

Question 35 : Long-sightedness is caused by the eyeball being too short. It can be corrected by the use of a :

Question 38 : An astronaut in a spaceship the sky appears black due to:

Question 39 : Intensity of light ray in a directionafter scattering by small particles (smaller than wavelength):

Question 40 : The danger signals installed at the top of tall buildings are red in&#160;colour. These can be easily seen from a distance because among all other colours, the red light:<br/>

Question 42 : In the white light of sun, maximum scattering by the air molecules present in the earth's atmosphere is for:<br>

Question 43 : Fill in the blank spaces by choosing the correct word.A prism is a piece of transparent material having three rectangular surfaces and .......... triangular surfaces.

Question 45 : If the image of distant objects is formed in front of the retina, the defect of vision may be

Question 46 : Which of the following observations cannot be explained by Tyndall Effect?

Question 47 : A defect, in which a person suffering from is unable to see in all directions equally well, is:

Question 48 : The&#160;split of white light into its constituent colours, by a triangular prism, is&#160;known as:

Question 49 : What are the colours of the Sun observed most during&#160;sunrise/sunset and noon?&#160;<br/>

Question 50 : The&#160;band of colours obtained on a screen on passing white light through a prism is&#160;called :

Question 52 : Assertion: The setting sun appears to be red. Reason: Scattering of light is directly proportional to the wavelength.

Question 53 : Assertion: Fine particles in atmosphere scatter the light of shorter wavelength more. Reason: Sky appears blue.

Question 55 : Larger particles scatter light at the ____ end of the spectrum the least. <br/>

Question 56 : Assertion: The setting sun appears to be red. Reason: Scattering of light is directly proportional to the wavelength.

Question 57 : Assertion: Incoming light reflected by earth is partially polarized. Reason: Atmospheric particle polarize the light.

Question 58 : At sunrise or sunset, the sun appears to be reddish white. This is because :

Question 61 : Which of the following phenomena cannot be explained by scattering of light ?

Question 65 : 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 66 : Larger particles scatter light at the ____ end of the spectrum the least. <br/>

Question 67 : In a beaker containing&#160;colloidal solution of sodium thiosulphate and a drop of con. sulphuric acid, light observed from side of beaker is:

Question 68 : Assertion: By roughening the surface of a glass sheet its transparency can be reduced. <br>Reason: Glass sheet with rough surface absorbs more light.

Question 72 : What characteristic property of light is responsible for the blue colour of the sky?<br>

Question 73 : At sunrise or sunset, the sun appears to be reddish white. This is because :

Question 75 : Which of the following phenomena cannot be explained by scattering of light ?

Question 79 : At sun rise or at sun set the sun appears to be reddish while at mid day it looks white. This is because

Question 80 : Assertion: Bluish colour predominates in a clear sky, since blue has a shorter wavelength and is scattered strongly. Reason: Blue has the shortest wavelength among all colours.

Question 83 : In a beaker containing&#160;colloidal solution of sodium thiosulphate and a drop of con. sulphuric acid, light observed from side of beaker is:

Question 84 : Assertion: Bluish colour predominates in a clear sky, since blue has a shorter wavelength and is scattered strongly. Reason: Blue has the shortest wavelength among all colours.

Question 87 : Assertion: Incoming light reflected by earth is partially polarized. Reason: Atmospheric particle polarize the light.

Question 89 : When is the direction of scattered light independent of the wavelength?

Question 91 : During scattering of light, the amount of scattering is inversely proportional to ________ of wavelength of light.

Question 92 : Assertion: In the absence of atmosphere the sky would appear black.<br/> Reason: Atmosphere scatters the light and hence we get blue colour.

Question 93 : Assertion: The setting sun appears to be red. <br>Reason: Scattering of light is directly proportional to the wavelength.

Question 94 : Assertion: A piece of red glass is heated till it glows in dark. The colour of glowing glass would be orange. Reason: Red and orange is complementary colours.

Question 95 : Assertion: In the absence of atmosphere the sky would appear black.<br/> Reason: Atmosphere scatters the light and hence we get blue colour.

Question 96 : When is the direction of scattered light independent of the wavelength?

Question 97 : Assertion: By roughening the surface of a glass sheet its transparency can be reduced. <br>Reason: Glass sheet with rough surface absorbs more light.

Question 98 : Assertion: The setting sun appears to be red. <br>Reason: Scattering of light is directly proportional to the wavelength.

Question 99 : 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 102 : The process of re-emission of absorbed light in all directions with different intensities by the atom or molecule is called ____________.

Question 103 : The angular magnification of telescope is $30$. If all the light which passes through objective lens of diameter $80 cm$ also passes through eye piece lens then find out diameter of eye piece lens.

Question 104 : The process of re-emission of absorbed light in all directions with different intensities by the atom or molecule is called ____________.

Question 105 : The defective condition of accommodation of the eye in which distant objects are clearly seen but near objects are indistinct is<br>

Question 106 : One of the following is not an example of incomplete sex-linkage

Question 107 : Myopia or near sightedness is a defect of eyes in which<br>

Question 109 : Two point white dots are 1 mm apart on a black paper. They are viewed by eye of diameter $3\ mm $.<br/>Approximately, what is the maximum distance at which these dots can be resolved by the eye?<br/>[ take wavelength of light &gt;500nm]

Question 110 : A normal eye is not able to see objects closer than $25$cm because?

Question 113 : In old age farsightedness is a defect of eye in man, in which

Question 114 : When the light rays converge at a point in front of the retina and then divert to form a blurred image on it, the defect is known as<br>

Question 115 : A person is wearing spectacles with concave lenses for correcting vision. While not using the glasses, the image of a distant object in his case will be formed<br>

Question 117 : To construct a ray diagram, you need a minimum of&#160; _______ ray(s) whose path(s) after refraction through the lens are known.

Question 118 : A ray of light passing through the .......... of the lens, passes on undeviated.

Question 119 : A ray of light travels from air to glass at an angle of incidence of $37^{\circ}$, the angle of refraction is $24^{\circ}$. What is the refractive index of glass?<br/>(Given: $\sin 37^{\circ} = 0.60, \sin 24^{\circ} = 0.40)$

Question 120 : State whether the following statement is True or False.&#160;<br/>A real image can be&#160;obtained by putting an object at any distance from a convex mirror

Question 121 : Assertion: Magnetic field lines are continuous and closed. Reason: Magnification of a convex mirror is always positive, but that of a concave mirror may be both positive or negative.

Question 122 : Which of the following mirrors forms an image which is virtual and smaller in size?

Question 124 : The image formed by the given convex mirror when it is inside focal distance is:

Question 125 : The magnification of an image by a convex lens is positive only when the project is placed:

Question 126 : Due to refraction, sunrise appears ______ sun comes to horizon&#160;and sunset appears______sun leaves horizon respectively.

Question 127 : Choose the correct answer:<br>The nature of image formed by convex mirror is:

Question 128 : The radius curvature for a convex lens is $40\ cm$, for each surface. Its refractive index is $1.5$. The local length will be

Question 130 : A camera is an optical instrument which makes use of a :

Question 131 : Ray optics fail when the size of the obstacle is :

Question 133 : The focal length of a concave lens is $2m$. Then the power of the lens is:<br/>

Question 135 : A man is unable to see closer than 1 m clearly.The power of lenses of his spectacles should be to see nearby object.

Question 136 : Which of the below is one of the laws of refraction?<br>

Question 137 : The power of a convex lens of focal length $2$ metre will be:

Question 139 : When the face is very close to the spoon the image formed by the outside bulged part?

Question 140 : No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be<br>

Question 141 : What is the angle of incidence when a ray of light incident on a concave mirror from its centre of curvature?

Question 142 : If $f$ is the focal length of a lens, then the power of the lens is equal to

Question 145 : Which of the following are common to images formed by both Concave and Convex lens ?

Question 147 : Fill in the blank.&#160;A _____ is a piece of transparent glass bounded by two spherical surfaces.&#160;

Question 148 : A convex mirror used for rear view on an automobile has a radius of curvature of 3.00m. If a bus is located at 5.00m from this mirror, find magnification?<br>

Question 149 : In case of a real and inverted image, the magnification of a mirror is:

Question 150 : The ratio of the sine of angle &#160;of incidence to the sine of angle of refraction is a constant for :

Question 151 : To observe the hydra bud clearly. Raju should see it first under the low power lens and then under the high power lens in order to see&#160;

Question 152 : 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 153 : Various optical instruments like telescopes, microscopes, camera uses which property of light?<br>

Question 155 : The angle of incidence for a ray of light passing&#160;through the centre of curvature of a concave mirror is :

Question 156 : 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 157 : A person sees his virtual image by holding a mirror very close to the face. When he moves the mirror away from his face, the imagebecomes inverted. What type of mirror he is using

Question 158 : "Value of refractive index remains same for light rays with different wavelength and for a particular material"

Question 160 : Material $1$ has an index of refraction of $1.15$.<br/>Material $2$ has an index of refraction of $2.30$.<br/>If light passes from air into each of these materials at the same angle of incidence, how will the angle of refraction in material $1$ compare to the angle of refraction in material $2$?

Question 161 : A person uses spectacles of power $+2\ D$. He is suffering from

Question 162 : A ray of light incident at a point on the principal axis of a convex lens passes undeviated through the lens. What special name is given to this point on the principal axis?<br>

Question 165 : The power of a lens being $+4$ dioptres suggests that it is a

Question 166 : A rod is placed in a beaker of full of water. It appears to be bent inside the water. Which of the following property of light is responsible for the rod appearing to be bent?

Question 167 : A ray of light travelling in air is incident on a denser surface at an angle of ${ 60 }^{ o }$. If the velocity of light in the denser medium is $2\times { 10 }^{ 8 }{ ms }^{ -1 }$, the angle of refraction inside the denser medium is :

Question 168 : A man can see distinctly from a distance of $0.5$ metre. If he wants to read a book placed at a distance of $25 \,cm$, then what should be the power of lens ?

Question 169 : A straight line graph is obtained by plotting sine of angle of incidence versus sine of angle of refraction. The slope of this graph represents :

Question 170 : A real object is placed at a distance&#160;$\dfrac{f}{2}$ in front of a concave mirror having focal length $f$. If object is&#160;shifted by a distance $\dfrac{f}{4}$ away from the mirror. Find the ratio of&#160;final magnification to initial magnification.

Question 172 : A beam of red light ($7000$ A.U. in air) in passing from air into a medium making an angle of incidence of $61^o$ and angle of refraction of $34^o$. find the wavelength of red light in the medium.

Question 173 : A square card of side length 1 mm is being seen through a magnifying lens of focal length 10 cm. The card is placed at a distance of 9 cm from the lens. The apparent area of the card through the lens is

Question 174 : A man can see only between $75\ cm$ and $200\ cm$. The power of lens to correct the near point will be

Question 175 : The near point and far point of a person are $40$ cm and $250$ cm respectively. Determine the power of the lens he/she should use while reading a book kept at distance $25$cm from the eye.

Question 176 : An object is placed at a distance of $f/2$ from a convex lens. The image will be

Question 178 : When light ray bends away from normal then which angle is larger?<br>

Question 179 : A short linear object of length $L$ lies on the axis of a spherical mirror of focal length $f$ at a distance $u$ from the mirror. Its image has an axial length $L$ equal to :

Question 180 : State whether true or false :A transparent material bound by two surfaces, of which one or both surfaces are spherical, forms a lens.

Question 181 : The image formed by objective lens of compound telescope will be:

Question 182 : In optical instruments, the lenses are used to form image by the phenomenon of

Question 183 : The relation among u, v and f for a mirror is

Question 184 : The image distance of an object placed $10\ cm%$ in front of a thin lens of focal length $5cm$ is

Question 185 : The frequency of a light wave in a material is $2\times 10^{14}$Hz and wavelength is $5000\overset{o}{A}$. The refractive index of material will be

Question 186 : The focal length of a concave mirror is $50\ cm.$ Where an object beplaced so that its image is two times and inverted

Question 187 : 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 188 : A simple magnifying lens is used in such a way that an image is formed at $25\ cm$ away from the eye. In order to have $10$ time magnification, the focal length of the lens should be

Question 189 : Refraction index of water is 4/3. Calculate speed of light in water.

Question 190 : A concave mirror forms the real image of an object which is magnified 4 times. The objects is moved 3 cm away, the magnification of the image is 3 times. What is the focal length of the mirror?

Question 191 : Images formed by which of the following arrangement isnot Virtual and erect ?

Question 193 : A lens forms a diminished and erect image of an object. The magnification is $\frac {1}{4}$. Find ratio of distance between object and focus and focus and image<br>

Question 194 : 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 195 : 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 196 : <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 197 : When a light ray moves from air to a transparent medium the angle of incidence and the angle of refraction are $45^{\circ}$ and $30^{\circ}$ respectively. Find the refractive index of this medium is

Question 198 : An under-water swimmer cannot see very clearly even in absolutely clear water because of:

Question 199 : Magnification produced is +$\dfrac { 1 }{ 3 }$, then what kind of mirror it is?

Question 200 : 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 202 : A beam of light passes through a sheet of plastic and out into the air. The beam makes&#160;${\theta}_{1}$&#160;angles with the normal as it passes through the plastic and&#160;the angle the beam of light makes with the normal as it passes into the air is&#160;${\theta}_{2}$.&#160;The refractive index for air is $1$&#160;and&#160;The refractive index&#160;for plastic is $2$.<br/>Calculate the value of $\sin{{\theta}_{2}}$, in terms of ${\theta}_{1}$?

Question 203 : The magnifications produced by a convex lens for two different of an object are $m_1$ and $m_2$ respectively $(m_1 &gt;m_2)$. If 'd' is the distance of separation between the two positions of the object then the focal length of the lens is

Question 204 : If the angle of incidence increases gradually then angle of refraction also_______.&#160;<br/>

Question 205 : A convex lens produces a double size real image when an object is placed at a distance of $18$ cm from it. Where should the object be placed to produce a triple size real image?

Question 206 : The power of a biconcave lens having a focal length of 25&#160;cm is:

Question 208 : Assertion: Air bubble shines in water. Reason: Air bubble in water shines due to refraction of light.

Question 209 : A ray of light falls on a transparent glass slab of refractive index $1.62$. What is the angle of incidence, if the reflected ray and reflected ray are mutually perpendicular ?

Question 210 : A ray of light travelling inside a rectangular glass block of refractive index $\sqrt2$ is incident on the glass-air surface at an angle o incidence of $45^o$.The refractive index of air is one. Under these conditions the ray will

Question 211 : When an object is placed on the principal axis of a convex lens at two different positions, it produces the images with magnification +2 and -4 respectively. How many times more away from the lens the image will be formed in the second position as compared to the first position?<br>

Question 212 : A convex lens has focal length $30$cm. If an object is placed at a distance of $15$cm from it then the magnification produced by the lens is?

Question 213 : 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 214 : 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 215 : The power of a lens is a measure of its degree of

Question 216 : After tracing the path of a ray of light passing through a rectangularglass slab for four different values of the angle of incidence, a studentreported his observations in tabular form as given below :<br><table class="wysiwyg-table"><tbody><tr><td><br>S.No</td><td>&lt;i</td><td>&lt;r</td><td>&lt; e</td></tr><tr><td><br>I</td><td>${30^0}$</td><td>${19^0}$</td><td>${29^0}$<br></td></tr><tr><td>II</td><td>${40^0}$</td><td>${28^0}$</td><td>${40^0}$</td></tr><tr><td>III</td><td>${50^0}$</td><td>${36^0}$</td><td>${50^0}$</td></tr><tr><td>IV</td><td>${60^0}$</td><td>${40^0}$</td><td>${59^0}$</td></tr></tbody></table>The best observation is :

Question 217 : 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 218 : Air has refractive index $1.0003$. Find the thickness of air column which will contain one more wavelength of yellow light of $6000$ $A^0$ than in same thickness of vacuum.

Question 219 : Aconvex lens of radii of curvature 20 cm and 30 cm respectively. It is silveredat the surface which has smaller radius of curvature. Then it will behave as $(\mu_g\, = \, 1.5)$

Question 220 : 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 221 : 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 222 : A ray of light going towards the centre of curvature of a convex mirror ............

Question 223 : 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 224 : The final image in an astronomical telescope is _______ the original object&#160;. Fill in the gap.<br/>

Question 225 : An object is placed at $30$ cm distance from a concave mirror of focal length $20$ cm, then nature, magnification of the image will be:

Question 226 : 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 227 : The reflecting surface is given by $y = \dfrac{10L}{\pi} \sin \dfrac{\pi x}{5L}$. The co-ordinates of the point where a horizontal ray becomes vertical after reflection is:

Question 228 : 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 229 : What happens when a ray of light is made to fall on a mirror along the normal?<br/>

Question 230 : 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 231 : The diameter of the reflecting surface of spherical mirror is called ..............

Question 232 : A point object is placed on the principal axis of the convex lens of focal length 20cm at a distance 40 cm to the left on it. The diameter of the lens is 10cm. If the eye is placed 60cm to the right of the lens at a distance h below the principal axis, then max value of 'h' to see the image is

Question 233 : The glancing angle of incidence is $10^{\circ}$. What will be the glancing angle of reflection?

Question 234 : 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 235 : 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 236 : An image of a bright square is obtained on a screen with the aid of a convergent lens. The distance between the square and the lens is $40\ cm$. The area of the image is nine times larger than that of the square. Select the correct statement(s).

Question 237 : A concave shaving mirror has a radius of curvature of 35.0 cm. It is positioned so that the (upright) image of a mans face is 2.50 times the size of the face. How far is the mirror from the face?

Question 238 : A $4.5 cm$ needle is placed $12 cm$ away from a convex mirror of focal length $15 cm$. Find the location of the image and the magnification.

Question 239 : 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 .

Question 240 : In the table below, column I lists various mirrors &#160;and lenses and column II their uses, qualities or properties.<br/><table class="wysiwyg-table"><tbody><tr><td>column &#160;I</td><td>Column II</td></tr><tr><td>I. Plane mirror</td><td>A. Feels thinner in the middle.</td></tr><tr><td>II. Concave mirror</td><td>B. Always forms virtual image.</td></tr><tr><td>III. Convex mirror</td><td>C. Always forms virtual image of smaller size.</td></tr><tr><td>IV. Concave lens&#160;</td><td>D.&#160;Is used by dentists to examine teeth.</td></tr><tr><td>V. Convex lens</td><td>E. Can be used as reading glass.<br/></td></tr></tbody></table>The correct matching is:

Question 242 : The image obtained while finding the focal length of convex lens is...................

Question 243 : Three convex lenses are available having focal lengths of $4 cm, 40 cm$ and $4 m$ respectively. Which one could be used as magnifying glass?

Question 244 : The angle between the incident ray and the normal is called ________.<br>

Question 245 : The distance between an object and its doubly magnified image by a concave mirror is: [ Assume $f$ = focal length]

Question 246 : 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 247 : In vacuum, to travel distance 'd', light takes time 't' and in medium to travel distance $'5d'$, it takes time 'T'. The critical angle of the medium is.<br>

Question 248 : Two thin lenses of power $+3.5D, -2D$ are placed in contact. Find the power of lens combination.

Question 249 : A spherical convex surface separates object and image space of refractive index $1$ and $4/3$ respectively. If radius of curvature of the surface s $0.1\ m$, its power is

Question 250 : A symmetric double convex lens is cut in two equal parts by a plane containing the principal axis. If the power of the original lens was 4 D, the power of a divided lens will be