Ray Optics PYQs Set 9 (PDF)

Set 9 of 18 · Questions 241-270 of 521

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Mere Teacher · Previous Year Questions JEE Main Physics · Ray Optics · Set 9 (Q241-270)
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241. $A concave mirror produces an image of an object such that the distance between the object and image is 20 cm. If the magnification of the image is ' -3 ', then the magnitude of the radius of curvature of the mirror is:$ (1) $30 cm$ (2) $3.75 cm$ (3) $15 cm$ (4) $7.5 cm$ 242. $The power of a lens (biconvex) is 1.25 in particular medium. Refractive index of the lens is 1.5 and radii of curvature are 20 cm and 40 cm respectively. The refractive index of surrounding medium :$ (1) $1.0$ (2) $\frac{9}{7}$ (3) $\frac{3}{2}$ (4) $\frac{4}{3}$ 243. $A ray of light is incident on a prism at the minimum deviation position. The angle of refraction at the first face (i.e., incident face) of the prism is$ (1) $zero$ (2) $30^{\circ}$ (3) $45^{\circ}$ (4) $60^{\circ}$ 244. $A spherical surface of radius of curvature , separates air from glass (refractive index ). The centre of curvature is in the glass medium. A point object ' ' placed in air on the optic axis of the surface, so that its real image is formed at ' ' inside glass. The line OI intersects the spherical surface at P and . The distance PO equals to$ (1) $5 R$ (2) $3 R$ (3) $1.5 R$ (4) $2 R$ 245. $The angle of incidence for a ray of light at a refracting surface of a prism is . The angle of prism is . If the ray suffers minimum deviation through the prism. the angle of ininimum deviation and refractive index of the material of the prism respectively, are [NEET 2016]$ (1) $30^{\circ} : 2$ (2) $45^{\circ}; 2$ (3) $30^{\circ}; \frac{1}{2}$ (4) $45^{\circ}; \frac{1}{2}$ 246. $In total internal reflection when the angle of incidence is equal to the critical angle for the pair of media in contact, what will be angle of refraction? [NEET 2019]$ (1) $0^{\circ}$ (2) $Equal to angle of incidence$ (3) $90^{\circ}$ (4) $180^{\circ}$ 247. $An object O is placed at 7 cm to the left of a concave mirror of radius of curvature 12 cm as shown in the figure. The position of the image will be at a distance of$ (1) $20 cm from the mirror to the left.$ (2) $30 cm from the mirror to the right.$ (3) $42 cm from the mirror to the left.$ (4) $42 cm from the mirror to the right.$ 248. $A small coin is resting on the bottom of a beaker filled with liquid. A ray of light from the coin travels upto the surface of the liquid and moves along its surface. How fast is the light travelling in the liquid?$ (1) $2.4 \times 1 0^{8} m / s$ (2) $3.0 \times 1 0^{8} m / s$ (3) $1.2 \times 1 0^{8} m / s$ (4) $1.8 \times 1 0^{8} m / s .$ 249. $A small source of light is 4 below the surface of water of refractive index 5/3. In order to cut off all the light, coming out of water surface, minimum diameter of the disc placed on the surface ofwater is$ (1) $6 m$ (2) $\infty$ (3) $3 m$ (4) $4 m .$ 250. $A symmetric thin biconvex lens is cut into four equal parts by two planes AB and CD as shown in figure. If the power of original lens is 4 D then the power of a part of the divided lens is$ (1) $D$ (2) $8 D$ (3) $2 D$ (4) $4 D$ 251. $An object is placed at a distance of 12 cm in front of a plane mirror. The virtual and erect image is formed by the mirror. Now the mirror is moved by 4 cm towards the stationary object. The distance by which the position of image would be shifted, will be$ (1) $4 cm towards mirror$ (2) $8 cm towards mirror$ (3) $8 cm away from mirror$ (4) $2 cm towards mirror$ 252. $A transparent cube of 0.21 m edge contains a small air bubble. Its apparent distance when viewed through one face of the cube is 0.10 m and when viewed from the opposite face is 0.04 m . The actual distance of the bubble from the second face of the cube is$ (1) $0.06 m$ (2) $0.17 m$ (3) $0.05 m$ (4) $0.04 m$ 253. $A beam of light consisting of red, green and blue colours is incident on a right angled prism. The refractive index of the material of the prism for the above red, green and blue wavelengths are 1.39, 1.44 and 1.47, respectively. The prism will:$ (1) $separate all the three colours from one another$ (2) $not separate the three colours at all$ (3) $separate the red colour part from the green and blue colours$ (4) $separate the blue coloure part from the red and green colours$ 254. $A green light is incident from the water to the air - water interface at the critical angle (θ). Select the correct statement.$ (1) $The entire spectrum of visible light will come out of the water at an angle of 90º to the normal.$ (2) $The spectrum of visible light whose frequency is less than that of green light will come out ot the air medium.$ (3) $The spectrum of visible light whose frequency is more than that of green light will come out to the air medium.$ (4) $The entire spectrum of visible light will come out of the water at various angles to the normal.$ 255. $The difference of speed of light in the two media A and B ( – ) is 2.6 x m/s. If the refractive index of medium B is 1.47, then the ratio of refractive index of medium B to medium A is : (Given : speed of light in vacuum c = 3 x )$ (1) $1.303$ (2) $1.318$ (3) $1.13$ (4) $0.12$ 256. $Two similar thin equiconvex lenses, of focal length each, are kept coaxially in contact with each other such that the focal length of the combination is . When the space between the two lenses is filled with glycerin (which has the same refractive index as that of glass) then the equivalent focal length is . The ratio will be$ (1) $3: 4$ (2) $2: 1$ (3) $1 : 2$ (4) $2: 3.$ 257. $A light wave travelling linearly in a medium of dielectric constant 4, incident on the horizontal interface separating medium with air. The angle of incidence for which the total intensity of incident wave will be reflected back into the same medium will be (Given : relative permeability of medium μ_{r} = 1)$ (1) $10°$ (2) $20°$ (3) $30°$ (4) $60°$ 258. $The focal length of converging lens is measured for violet, green and red colours. It is respectively f_{v}, f_{g}, f_{r} . We will get$ (1) $f_{v} < f_{r}$ (2) $f_{g} > f_{r}$ (3) $f_{v} = f_{g}$ (4) $f_{g} < f_{r} .$ 259. $Two identical objects are placed in front of convex mirror and concave mirror having same radii of curvature of 12 cm, at same distance of 18 cm from the respective mirrors. The ratio of sizes of the images formed by convex mirror and by concave mirror is:$ (1) $2$ (2) $1/2$ (3) $1/3$ (4) $3$ 260. $A thin prism of angle made of glass of refractive index is combined with another prism of glass of refractive index . The combination of the prisms produces dispersion without deviation. The angle of the second prism should be$ (1) $5^{o}$ (2) $7^{o}$ (3) $1 0^{o}$ (4) $1 2^{o}$ 261. $A spherical surface separates two media of refractive indices 1 and 1.5 as shown in figure. Distance of the image of an object ' ', is:( C is the center of curvature of the spherical surface and is the radius of curvature)$ (1) $0.24 m left to the spherical surface$ (2) $0.24 m right to the spherical surface$ (3) $0.4 m left to the spherical surface$ (4) $0.4 m right to the spherical surface$ 262. $A vessel of depth d is half filled with oil of refractive index hi and the other half is filled with water of refractive index . The apparent depth of this vessel when viewed from above will be-$ (1) $\frac{2 d ( n _{1} + n _{2} )}{n _{1} + n _{2}}$ (2) $\frac{d ( n _{1} + n _{2} )}{2 n _{1} n _{2}}$ (3) $\frac{d n _{1} n _{2}}{2 ( n _{1} + n _{2} )}$ (4) $\frac{d n _{1} n _{2}}{( n _{1} + n _{2} )}$ 263. $An upright object is placed at a distance of 40 cm in frontof a convergent lens of focal length 20 cm . A convergentmirror of focal length 10 cm is placed at a distance of 60 cm on the other side of the lens. The position and size of thefinal image will be:$ (1) $20 cm from the convergent mirror, same size as theobject$ (2) $40 cm from the convergent mirror, same size as theobject$ (3) $40 cm from the convergent lens, twice the size of the object$ (4) $20 cm from the convergent mirror, twice the size of the object$ 264. $A thin convex lens made from crown glass has focal length f. When it is measured in two different liquids having refractive indices and , it has the focal lengths f1 and f2 respectively. The correct relation between the focal length is :$ (1) $f1 = f2 < f$ (2) $f1 > f and f2 becomes negative$ (3) $f2 > f and f1 becomes negative$ (4) $f1 and f2 both become negative$ 265. $The position of final image formed by the given lens combination from the third lens will be at a distance of (f_{1} = + 10 cm, f_{2} = - 10 cm), and (f_{3} = + 30 cm)$ (1) $15 cm .$ (2) $infinity$ (3) $45 cm$ (4) $30 cm$ 266. $The radius of curvature of each surface of a convex lens having refractive index 1. 8 is 20 cm. The lens is now immersed in a liquid of refractive index 1. 5. The ratio of power of lens in air to its power in the liquid will be x : 1. The value of x is$ 267. $Light from a point source in air falls on a spherical glass surface (refractive index, and radius of curvature ). The image is formed at a distance of 200 cm from the glass surface inside the glass. The magnitude of distance of the light source from the glass surface is ____ m.$ 268. $Two transparent media having refractive indices 1. 0 and 1. 5 are separated by a spherical refracting surface of radius of curvature 30 cm. The centre of curvature of surface is towards denser medium and a point object is placed on the principal axis in rarer medium at a distance of 15 cm from the pole of the surface. The distance of image from the pole of the surface is cm.$ 269. $A container contains a liquid with refractive index of 1.2 up to a height of 60 cm and another liquid having refractive index 1.6 is added to height H above first liquid. If viewed from above, the apparent shift in the position of bottom of container is 40 cm. The value of H is _________ cm. (Consider liquids are immisible)$ 270. $A light ray enters a solid glass sphere of refractive index at an angle of incidence . The ray is both reflected and refracted at the farther surface of the sphere. The angle (in degrees) between the reflected and refracted rays at this surface is$