Ray Optics PYQs Set 7 (PDF)

Set 7 of 16 · Questions 181-210 of 467

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Mere Teacher · Previous Year Questions NEET Physics · Ray Optics · Set 7 (Q181-210)
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181. $When an object is placed 40 cm away from a spherical mirror an image of magnification \frac{1}{2} is produced. To obtain an image with magnification of \frac{1}{3}, the object is to be moved:$ (1) $20 cm away from the mirror.$ (2) $20 cm towards the mirror.$ (3) $80 cm away from the mirror.$ (4) $40 cm away from the mirror.$ 182. $A satisfactory photographic print is obtained when the exposure time is 10 sec at a distance of 2 m from a 60 cd lamp. The time of exposure required for the same quality print at a distance of 4 m from a 120 cd lamp is$ (1) $5 sec$ (2) $10 sec$ (3) $15 sec$ (4) $20 sec$ 183. $5 The refractive index of the material of a glass prism is . The angle of minimumdeviation is equal to the angle of the prism. What is the angle of the prism?$ (1) $60^{\circ}$ (2) $58^{\circ}$ (3) $48^{\circ}$ (4) $50^{\circ}$ 184. $When the power of eye lens increases, the defect of vision is produced. The defect is known as$ (1) $Shortsightedness$ (2) $Long-sightedness$ (3) $Colorblindness$ (4) $None of the above$ 185. $The magnifications produced by a convex lens for two position of an object are 4 and 3, respectively. If the distance of separation between the two positions of the object is 2 cm, then the focal length of the lens is$ (1) $20 cm$ (2) $16 cm$ (3) $28 cm$ (4) $24 cm$ 186. $An effective power of a combination of 5 identical convex lenses which are kept in contact along the principal axis is 25 D. Focal length of each of the convex lens is :$ (1) $20 cm$ (2) $50 cm$ (3) $500 cm$ (4) $25 cm$ 187. $The focal length of a plano convex lens is and its refractive index is 1.5 . It is kept over a plane glass plate with its curved surface touching the glass plate. The gap between the lens and the glass plate is filled by a liquid. As a result, the effective focal length of the combination becomes . Then the refractive index of the liquid is$ (1) $1.5$ (2) $2$ (3) $1.25$ (4) $1.33$ 188. $In the diagram given below, there are three lenses formed. Considering negligible thickness of each of them as compared to (R_{1}) and (R_{2}), i.e., the radii of curvature for upper and lower surfaces of the glass lens, the power of the combination is$ (1) $\frac{1}{6} (\frac{1}{( R _{1} )} - \frac{1}{( R _{2} )})$ (2) $- \frac{1}{6} (\frac{1}{( R _{1} )} + \frac{1}{( R _{2} )})$ (3) $\frac{1}{6} (\frac{1}{( R _{1} )} + \frac{1}{( R _{2} )})$ (4) $- \frac{1}{6} (\frac{1}{( R _{1} )} - \frac{1}{( R _{2} )})$ 189. $A diverging lens with magnitude of focal length 25cm is placed at a distance of 15 cm from a converging lens of magnitude of focal length 20 cm. A beam of parallel light falls on the diverging lens. The final image formed is :$ (1) $real and at a distance of 6 cm from the convergent lens$ (2) $real and at a distance of 40 cm from convergent lens.$ (3) $virtual and at a distance of 40 cm from convergent lens$ (4) $real and at distance of 40 cm from the divergent lens.$ 190. $Two slits in Young’s experiment have widths in the ratio 1 : 25. The ratio of intensity at the maxima and minima in the interference pattern, is$ (1) $\frac{49}{121}$ (2) $\frac{4}{9}$ (3) $\frac{9}{4}$ (4) $\frac{121}{49} .$ 191. $The far point of a near sighted person is 6.0 m from her eyes, and she wears contacts that enable her to see distant objects clearly. A tree is 18.0 m away 2.0 m high. How high is the image formed by the contacts?$ (1) $0.1 m$ (2) $1.5 m$ (3) $0.75 m$ (4) $0.50 m$ 192. $A convex lens is put 10 cm from a light source and it makes a sharp image on a screen, kept 10 cm from the lens. Now a glass block (refractive index 1.5) of 1.5 cm thickness is placed in contact with the light source. To get the sharp image again,, the screen is shifted by a distance d. Then d is :$ (1) $1.1 cm away from the lens$ (2) $0.55 cm away from the lens$ (3) $0.55 cm towards the lens$ (4) $0$ 193. $A finite size object is placed normal to the principal axis at a distance of 30 cm from a convex mirror of focal length 30 cm. A plane mirror is now placed in such a way that the image produced by both the mirrors coincide with each other. The distance between the two mirrors is:$ (1) $45 cm$ (2) $15 cm$ (3) $22.5 cm$ (4) $7.5 cm$ 194. $The angle of incidence for a ray oflight at a refracting surface of a prism is . The angle of prism is . If the ray suffers minimum deviation through the prism, the angle of minimum deviation and refractive index ofthe material ofthe prism respectively, are$ (1) $4 5^{\circ}; 2$ (2) $3 0^{\circ}; \frac{1}{2}$ (3) $4 5^{\circ}; \frac{1}{2}$ (4) $3 0^{\circ}; 2 .$ 195. $A hemispherical vessel is completely filled with a liquid of refractive index . A small coin iskept at the lowest point of the vessel as shown in figure. The minimum value of the refractive index of the liquid so that a person can see the coin from point E (at the level of the vessel) is$ (1) $3$ (2) $\frac{3}{2}$ (3) $\frac{3}{2}$ (4) $2$ 196. $A convex lens is made of 3 layers of glass of 3 different materials as in the figure. A point object is placed on its axis. The number of images of the object are$ (1) $3$ (2) $4$ (3) $1$ (4) $2$ 197. $An object is placed at a distance of 40 cm from a concave mirror of focal length 15 cm. If the object is displaced through a distance of 20 cm towards the mirror, the displacement of the image will be$ (1) $30 cm away from the mirror$ (2) $36 cm towards the mirror$ (3) $30 cm towards the mirror$ (4) $36 cm away from the mirror$ 198. $The speed of light in media M1 and M2 are 1.5 \times 1 0^{8} m/s and 2.0 \times 1 0^{8} m/s respectively. A ray of light enters from medium M1 to M2 at an incidence angle i. If the ray suffers total internal reflection, the value of i is$ (1) $Equal to sin^{- 1} (\frac{3}{4})$ (2) $Equal to or less than sin^{- 1} (\frac{3}{4})$ (3) $Equal to or greater than sin^{- 1} (\frac{3}{4})$ (4) $Less than sin^{- 1} (\frac{3}{4})$ 199. $Two objects A and B arc placed at 15 cm and 25 cm from the pole in front of a concave mirror having radius of curvature 40 cm. The distance between images formed by the mirror is:$ (1) $40 cm$ (2) $60 cm$ (3) $160cm$ (4) $100cm$ 200. $5. In a double slit experiment, when light of wavelength 400 nm was used, the angular width of the first minima formed on a screen placed 1 m away, was found to be 0. 2^{o} . What will be the angular width of the first minima, if the entire experimental apparatus is immersed in water?.of the$ (1) $0. 1^{o}$ (2) $0.26 6^{o}$ (3) $0.1 5^{o}$ (4) $0.0 5^{o}$ 201. $A ray of light is incident on a surface of glass slab at an angle . If the lateral shift produced per unit thickness is , the angle of refraction produced is$ (1) $tan^{- 1} (\frac{3}{2})$ (2) $tan^{- 1} (1 - \frac{2}{3})$ (3) $sin^{- 1} (1 - \frac{2}{3})$ (4) $tan^{- 1} (\frac{2}{3 - 1})$ 202. $Figure shows a mixture of blue, green and red coloured rays incident normally on a right angled prism. The critical angles of the material of the prism for red, green and blue are 46^{\circ}, 44^{\circ} and 43^{\circ} respectively. The arrangement will separate$ (1) $green colour from red and blue$ (2) $all the three colours$ (3) $red colour from blue and green$ (4) $blue colour from red and green.$ 203. $Two plane mirrors are inclined to each other such that a ray of light incident on the first mirror (M_{1}) and parallel to the second mirror (M_{2}) is finally reflected from the second mirror (M_{2}) parallel to the first mirror (M_{1}) . The angle between the two mirrors will be:$ (1) $45^{\circ}$ (2) $60^{\circ}$ (3) $75^{\circ}$ (4) $90^{\circ}$ 204. $If a convex lens of focal length 80 cm and a concave lens of focal length 50 cm are combined together, what will be their resulting power?.$ (1) $+ 7.5 D$ (2) $- 0.75 D$ (3) $+ 6.5 D$ (4) $- 6.5 D .$ 205. $What is the lateral shift of a ray refracted through a parallel-sided glass slab of thickness ' ' in terms of the angle of incidence ' ' and angle of refraction ' ', if the glass slab is placed in air medium?$ (1) $\frac{h tan ( i - r )}{tan r}$ (2) $\frac{h sin ( i - r )}{cos r}$ (3) $h$ (4) $\frac{h cos ( i - r )}{sin r}$ 206. $The angle of deviation through a prism is minimum when Incident ray and emergent ray are symmetric to the prism(B) The refracted ray inside the prism becomes parallel to its base(C) Angle of incidence is equal to that of the angle of emergence When angle of emergence is double the angle of incidence Choose the correct answer from the optionsgiven below :$ (1) $Statements (A), (B) and (C) are true$ (2) $Only statement (D) is true$ (3) $Only statements (A) and (B) are true$ (4) $Statements (B) and (C) are true$ 207. $A ray is incident at an angle of incidence i on one surface of a small angle prism (with angle of prism A) and emerges normally from the opposite surface. If the refractive index of the material of the prism is µ, then the angle of incidence is nearly equal to [NEET 2020]$ (1) $\frac{2 A}{μ}$ (2) $µA$ (3) $\frac{μA}{2}$ (4) $\frac{A}{2 μ}$ 208. $A photograph of a landscape is captured by a drone camera at a height of 18 km. The size of the camera film is 2 cm \times 2 cm and the area of the landscape photographed is 400 km^{2} . The focal length of the lens in the drone camera is:$ (1) $1.8 cm$ (2) $0.9 cm$ (3) $2.8 cm$ (4) $2.5 cm$ 209. $As shown in the diagram, when the incident ray is parallel to base of the prism, the emergent ray grazes along the second surface.If refractive index of the material of prism is , the angle of prism is.$ (1) $60^{\circ}$ (2) $45^{\circ}$ (3) $90^{\circ}$ (4) $75^{\circ}$ 210. $Adisc is placed on asurface ofpond which has refractive index 5/3. Asource oflight is placed 4 below the surface of liquid. The minimum radius of disc needed so that light is not coming out is,$ (1) $\infty$ (2) $3 m$ (3) $6m$ (4) $4m$