Ray Optics PYQs Set 16 (PDF)

Set 16 of 18 · Questions 451-480 of 521

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Mere Teacher · Previous Year Questions JEE Main Physics · Ray Optics · Set 16 (Q451-480)
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451. $A man is suffering from colour blindness for green colour. To remove this defect, he should use goggles of$ (1) $Green colour glasses$ (2) $Red colour glasses$ (3) $Smoky colour glasses$ (4) $None of the above$ 452. $A camera objective has an aperture diameter d. If the aperture is reduced to diameter d /2, the exposure time under identical conditions of light should be made$ (1) $2 fold$ (2) $2 fold$ (3) $22 fold$ (4) $4 fold$ 453. $The focal length f is related to the radius of curvature r of the spherical convex mirror by -$ (1) $f = r$ (2) $f = - \frac{1}{2} r$ (3) $f = + \frac{1}{2} r$ (4) $f = - r$ 454. $Formation of real image using a biconvex lens is shown below :$ (1) $Erect real image$ (2) $No change$ (3) $Image disappears$ (4) $Magnified image$ 455. $A lens is placed between a source oflight and a wall. It forms images of area A_{1} and A_{2} on the wall, for its two different positions. The area of the source oflight is$ (1) $\frac{A _{1} - A _{2}}{2}$ (2) $\frac{1}{A _{1}} + \frac{1}{A _{2}}$ (3) $A_{1} A_{2}$ (4) $\frac{A _{1} + A _{2}}{2} .$ 456. $Two plane mirrors are inclined to each other such that a ray of light incident on the first mirror (M_{1}) and parallel to the second mirror (M_{2}) is finally reflected from the second mirror (M_{2}) parallel to the first mirror (M_{1}). The angle between the two mirrors will be :$ (1) $75º$ (2) $90º$ (3) $45º$ (4) $60º$ 457. $A plano convex lens is made of refractive index 1.6. The radius of curvature of the curved surface is 60 cm. The focal length of the lens is$ (1) $200 cm$ (2) $100 cm$ (3) $50 cm$ (4) $400 cm.$ 458. $A double convex lens has focal length 25 cm. The radius of curvature of one of the surfaces is double of the other. Find the radii if the refractive index of the material of the lens is 1.5.$ (1) $100 cm, 50 cm$ (2) $25 cm, 50 cm$ (3) $18.75 cm, 37.5 cm$ (4) $50 cm, 100 cm$ 459. $In a Fresnel biprism experiment, the two positions of lens give separation between the slits as 16 cm and 9 cm respectively. What is the actual distance of separation?.$ (1) $13 cm$ (2) $14 cm$ (3) $12.5 cm$ (4) $12 cm.$ 460. $Time taken by sunlight to pass through a window of thickness 4 mm whose refractive index is is$ (1) $2 \times 1 0^{- 4} s$ (2) $2 \times 1 0^{8} s$ (3) $2 \times 1 0^{- 11} s$ (4) $2 \times 1 0^{11} s .$ 461. $A beam of light from a souce L is incident normally on a plane mirror fixed at a certain distance x from the source. The beam is reflected back as a spot on a scale placed just above the source L. When the mirror is rotated through a small angle θ, the spot of the light is found to move through a distance y on the scale. The angle θ is given by :$ (1) $\frac{y}{2 x}$ (2) $\frac{y}{x}$ (3) $\frac{x}{2 y}$ (4) $\frac{x}{y}$ 462. $The refracting angle of a prism is A and refractive index of the material of the prism is cot (A/2). Then the angle of minimum deviation will be –$ (1) $180-2A$ (2) $90-A$ (3) $180+ 2A$ (4) $180-3A$ 463. $Two identical glass (μ_{g} = 3/2) equiconvex lenses of focal length f each are kept in contact. The space between that two lenses in filled with water (μ_{w} = 4/3). The focal length of the combination is$ (1) $\frac{3 f}{4}$ (2) $\frac{f}{3}$ (3) $f$ (4) $\frac{4 f}{3}$ 464. $In Young’s experiment, two coherent sources are placed 0.90 mm apart and fringes are observed one metre away. If it produces second dark fringe at a distance of 1 mm from central fringe, the wavelength of monochromatic light is used would be$ (1) $60 \times 1 0^{- 4} c m$ (2) $10 \times 1 0^{- 4} c m$ (3) $10 \times 1 0^{- 5} c m$ (4) $6 \times 1 0^{- 5} c m .$ 465. $A prism of refractive index and angle of prism A is placed in the position of minimum angle of deviation. If minimum angle of deviation is also A, then in terms of refractive index$ (1) $2 cos^{- 1} (\frac{μ}{2})$ (2) $sin^{- 1} (\frac{μ}{2})$ (3) $sin^{- 1} (\frac{μ - 1}{2})$ (4) $cos^{- 1} (\frac{μ}{2})$ 466. $The exposure time of a camera a lens at f/2.8 setting is 1/200 seconds. The correct time of exposure for f/5.6 setting is -$ (1) $0.04 sec$ (2) $0.20 sec$ (3) $0.40 sec$ (4) $0.02 sec$ 467. $Two identical symmetric double convex lenses of focal length f are cut into two equal parts L_{1}, L_{2} by AB plane and L_{3}, L_{4} by XY plane as shown in figure respectively. The ratio of focal lengths of lenses L_{1} and L_{3} is$ (1) $1 : 1$ (2) $1 : 2$ (3) $1 : 4$ (4) $2 : 1$ 468. $The frequency of a light wave in a material is and wavelength is . The refractive index of material will be$ (1) $1.50$ (2) $3.00$ (3) $1.33$ (4) $1.40.$ 469. $When a biconvex lens of glass having refractive index 1.47 is dipped in a liquid, it acts as a plane sheet of glass . This implies that the liquid must have refractive index.$ (1) $equal to that of glass$ (2) $less then one$ (3) $greater than that of glass$ (4) $less then that of glass$ 470. $The angle incidence for a ray of light at a refracting surface of a prism is 45º. The angle of prism is 60º. If the ray suffers minimum deviation through the prism, the angle of minimum deviation and refractive index of the material of the prism respectively, are$ (1) $30º; \frac{1}{2}$ (2) $45º ; \frac{1}{2}$ (3) $30º ; 2$ (4) $45º ; 2$ 471. $A plano convex lens of refractive index and focal length is kept in contact with another plano concave lens of refractive index and focal length . If the radius of curvature of their spherical faces is R each and = , then and are related as :$ (1) $2μ1 - μ2 = 1$ (2) $μ1 + μ2 = 3$ (3) $3μ2 - 2μ1 = 1$ (4) $2μ2 - μ1 = 1$ 472. $Let u and v be the distances of the object and the image from a lens of focal length f . The correct graphical representation of u and v for a convex lens when \| u \| >, is$ (1) (2) (3) (4) 473. $If are the angle of refraction at first face and second face of a prism, then the angle of the prism is$ (1) $r_{1} - r_{2}$ (2) $r_{1} - r_{2} 2$ (3) $r_{1} + r_{2} 2$ (4) $r_{1} + r_{2}$ 474. $Exposure time of camera lens at f /2.8 setting is 1/200 second. The correct time of exposure at f /5.6 is$ (1) $0.20 second$ (2) $0.40 second$ (3) $0.02 second$ (4) $0.04 second$ 475. $A thin prism having refracting angle is made of glass of refractive index 1.42. This prism is combined with another thin prism of glass of refractive index 1.7. This combination produces dispersion without deviation. The refracting angle of second prism should be$ (1) $6^{o}$ (2) $8^{o}$ (3) $1 0^{o}$ (4) $4^{o}$ 476. $In human eye the focussing is done by$ (1) $To and fro movement of eye lens$ (2) $To and fro movement of the retina$ (3) $Change in the convexity of the lens surface$ (4) $Change in the refractive index of the eye fluids$ 477. $Image formed on the retina is$ (1) $Real and inverted$ (2) $Virtual and erect$ (3) $Real and erect$ (4) $Virtual and inverted$ 478. $The refracting angle of a prism 'A', and refractive index of the material of the prism is cot(A/2). The angle of minimum deviation is :$ (1) $18 0^{\circ} - 2 A$ (2) $9 0^{\circ} - A$ (3) $18 0^{\circ} + 2 A$ (4) $18 0^{\circ} - 3 A$ 479. $A ray of light passing through a prism suffers minimum deviation. It is found that the angle of incidence is double the angle of refraction within the prism. Then, the angle of prism is ____ (in degrees)$ 480. $A convex lens of refractive index and focal length 18 cm in air is immersed in water, The change in focal length of the lens will be_____cm. (Given refractive index of water = )$