Ray Optics PYQs Set 12 (PDF)

Set 12 of 18 · Questions 331-360 of 521

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Mere Teacher · Previous Year Questions JEE Main Physics · Ray Optics · Set 12 (Q331-360)
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331. $For an object placed at a distance 2.4 m from a lens, a sharp focused image is observed on a screen placed at a distance 12 cm from the lens. A glass plate of refractive index 1.5 and thickness 1 cm is introduced between lens and screen such that the glass plate plane faces parallel to the screen. By what distance should the object be shifted so that a sharp focused image is observed again on the screen?$ (1) $0.8m$ (2) $3.2m$ (3) $1.2m$ (4) $5.6m$ 332. $The variation of refractive index of a crown glass thin prism with wavelength of the incident light is shown. Which of the following graphs is the correct one, if is the angle of minimum deviation ?$ (1) (2) (3) (4) 333. $A conversing beam of rays is incident on a diverging lens. Having passed though the lens the rays intersect at a point 15 cm from the lens on the opposite side. If the lens is removed the point where the rays meets will move 5 cm closer to the lens. The focal length of the lens is :$ (1) $- 10 cm$ (2) $20 cm$ (3) $- 30 cm$ (4) $5 cm$ 334. $The graph shows how the magnification m produced by a thin lens varies with image distance v . What is the focal length of the lens used?$ (1) $\frac{b ^{2}}{ac}$ (2) $\frac{b ^{2} c}{a}$ (3) $\frac{a}{c}$ (4) $\frac{b}{c}$ 335. $A ray of light is travelling from glass to air. (Refractive index of glass ). The angle of incidence is . The deviation of the ray is$ (1) $0^{\circ}$ (2) $80^{\circ}$ (3) $50^{\circ} - sin^{- 1} (\frac{sin 50 ^{\circ}}{1.5})$ (4) $sin^{- 1} (\frac{sin 50 ^{\circ}}{1.5}) - 50^{\circ}$ 336. $An image is formed at a distance of from the glass surface when light from point source in air falls on a spherical glass surface with refractive index 1.5. The distance of the light source from the glass surface is . The radius of curvature is$ (1) $20 cm$ (2) $40 cm$ (3) $30 cm$ (4) $50 cm$ 337. $A plano convex lens fits exactly into a plano concave lens. Their plane surfaces are parallel to each other. Iflenses are made of different materials of refractive indices and and is the radius of curvature ofthe curved surface ofthe lenses, then the focal length of the combination is$ (1) $\frac{R}{( μ _{1} - μ _{2} )}$ (2) $\frac{2 R}{( μ _{2} - μ _{1} )}$ (3) $\frac{R}{2 ( μ _{1} + μ _{2} )}$ (4) $\frac{R}{2 ( μ _{1} - μ _{2} )} .$ 338. $Region I and II are separated by a spherical surface of radius 25cm. An object is kept in region I at a distance of 40cm from the surface. The distance of the image from the surface is :$ (1) $55.44cm$ (2) $9.52cm$ (3) $18.23cm$ (4) $37.58cm$ 339. $Consider a point object situated at a distance of from the centre of sphere of radius and refractive index 1.5 as shown in the figure. If the refractive index of the region surrounding this sphere is 1.4 , then the position of the image due to refraction by sphere with respect to the centre is$ (1) $30 cm$ (2) $45 cm$ (3) $\infty$ (4) $28 cm$ 340. $A convex lens A of focal length 20 cm and a concave lens B of focal length 5 cm are kept along the same axis with a distance d between them. If a parallel beam of light falling on A leaves B as a parallel beam, then the distance d (in cm) will be [NEET 2021]$ (1) $25$ (2) $15$ (3) $50$ (4) $30$ 341. $Light travels in two media M_{1} and M_{2} with speeds 1.5 x 1 0^{8} m s^{- 1} and 2.0 x 1 0^{8} m s^{- 1} respectively. The critical angle between them is:$ (1) $tan^{- 1} (\frac{3}{7})$ (2) $tan^{- 1} (\frac{2}{3})$ (3) $cos^{- 1} (\frac{3}{4})$ (4) $sin^{- 1} (\frac{2}{3})$ 342. $A transparent block A having refractive index is surrounded by another medium of refractive index as shown in the figure. A light ray is incident on the flat face of the block with incident angle as shown in the figure. What is the maximum value of for which light suffers total internal reflection at the top surface of the block?$ (1) $tan^{- 1} (4/3)$ (2) $sin^{- 1} (3/4)$ (3) $tan^{- 1} (3/4)$ (4) $cos^{- 1} (3/4)$ 343. $Two similar thin equi-convex lenses, of focal length f each, are kept co-axially in contact with each other such that the focal length of the combination is . When the space between the two lenses is filled with glycerine (which has the same refractive index ( ) as that of glass) then the equivalent focal length is . The ratio will be [NEET 2019]$ (1) $1 : 2$ (2) $2 : 3$ (3) $3 : 4$ (4) $2 : 1$ 344. $A ray of light is incident on a prism of prism angle 60º at the minimum deviation position. The angle of refraction at the first face (i.e., incident face) of the prism is$ (1) $zero$ (2) $30°$ (3) $45°$ (4) $60°$ 345. $A slanted object AB is placed on one side of convex lens as shown in the diagram. The image is formed on the opposite side. Angle made by the image with principal axis is:$ (1) $- α$ (2) $- α 2$ (3) $- 45^{\circ}$ (4) $+ 45^{\circ}$ 346. $A 2 meter long scale with least count of 0. 2 cm is used to measure the locations of objects on an optical bench. While measuring the focal length of a convex lens, the object pin and the convex lens are placed at 80 cm mark and 1 m mark, respectively. The image of the object pin on the other side of lens coincides with image pin that is kept at 180 cm mark. The % error in the estimation of focal length is:$ (1) $0.85$ (2) $1.70$ (3) $1.02$ (4) $0.51$ 347. $In young’s double slit experiment the distance between the slits and the screen is doubled. The separation between the slits is reduced to half. As a result the fringe width$ (1) $is halved$ (2) $becomes four times$ (3) $remains unchanged$ (4) $is doubled.$ 348. $One plano-convex and one plano-concave lens of same radius of curvature but of different materials are joined side by side as shown in the figure. If the refractive index of the material of is and that of is then the focal length of the combination is:$ (1) $\frac{R}{μ _{1} - μ _{2}}$ (2) $\frac{2 R}{μ _{1} - μ _{2}}$ (3) $\frac{2 R}{2 ( μ _{1} - μ _{2} )}$ (4) $\frac{R}{2 - ( μ _{1} - μ _{2} )}$ 349. $Diameter of a plano - convex lens is 6 cm and thickness at the centre is 3 mm. If speed of light in material of lens is 2 \times 108 m/s, the focal length of the lens is :$ (1) $15 cm$ (2) $20 cm$ (3) $30 cm$ (4) $10 cm$ 350. $A thin Plano convex lens made of glass of refractive index 1.5 is immersed in a liquid ofrefractive index 1.2. When the plane side of the lens is silver coated for complete reflection, the lens immersed in the liquid behaves like a concave mirror of focal length 0.2 m. The radius of curvature of the curved surface of the lens is$ (1) $0.20 m$ (2) $0.25 m$ (3) $0.15 m$ (4) $0.10 m$ 351. $A ray of light from a denser medium strikes a rare medium as shown in figure. The reflected andrefracted rays make an angle of with each other. The angles of reflection and refraction are and The critical angle would be$ (1) $s i n_{(}^{- ⊥} t an r_{)}$ (2) $s i n_{(}^{- 1} s in r_{)}$ (3) $co s_{(}^{- 1} t an r_{)}$ (4) $t a n_{(}^{- 1} s in r_{)}$ 352. $A lens having focal length f and aperture of diameter d forms an image of intensity I . Aperture of diameter \frac{d}{2} in central region of lens is covered by a black paper. Focal length of lens and intensity of image now will be respectively$ (1) $f and \frac{I}{4}$ (2) $\frac{3 f}{4} and \frac{I}{2}$ (3) $f and \frac{3 I}{4}$ (4) $\frac{f}{2} and \frac{I}{2} .$ 353. $An object is placed at a distance of 12cm from a convex lens. A convex mirror of focal length 15cm is placed on other side of lens at 8cm as shown in the figure. Image of object coincides with the object. When the convex mirror is removed, a real and inverted image is formed at a position. The distance of the image from the object will be$ 354. $The distance between object and its 3 times magnified virtual image as produced by a convex lens is 20 cm . The focal length of the lens used is_____cm .$ 355. $As shown in the figure, a combination of a thin piano concave lens and a thin piano convex lens is used to image an object placed at infinity. The radius of curvature of both the lenses is 30 cm and refraction index of the material for both the lenses is 1.75. Both the lenses are placed at distance of 40 cm from each other. Due to the combination , the image of the object is formed at distance x = _______cm, from concave lens.$ 356. $A parallel beam of light is allowed to fall on a transparent spherical globe of diameter 30 cm and refractive index 1.5. The distance from the centre of the globe at which the beam of light can converge is_________mm.$ 357. $A thin cylindrical rod of length 10 cm is placed horizontally on the principle axis of a concave mirror of focal length 20 cm. The rod is placed in a such a way that mid point of the rod is at 40 cm from the pole of mirror. The length of the image formed by the mirror will be \frac{x}{3} cm. The value of x is$ 358. $Distance between object and its image (magnified by - \frac{1}{3}) is 30 cm. The focal length of the mirror used is (\frac{x}{4}) cm, where magnitude of value of x is _______ .$ 359. $A pole is vertically submerged in swimming pool, such that it gives a length of shadow 2.15m within water when sunlight is incident at an angle of 30 ° with the surface of water. If swimming pool is filled to a height of 1.5 m, then the height of the pole above the water surface in centimeters is (n_{ω} = \frac{4}{3})_____.$ 360. $Two immiscible liquids of refractive indices and respectively are put in a beaker as shown in the figure. The height of each column is . A coin is placed at the bottom of the beaker. For near normal vision, the apparent depth of the coin is . The value of is_______$