Ray Optics PYQs Set 15 (PDF)

Set 15 of 18 · Questions 421-450 of 521

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Mere Teacher · Previous Year Questions JEE Main Physics · Ray Optics · Set 15 (Q421-450)
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421. $An object is placed at the focus of concave lens having focal length f. What is the magnification and distance of the image from the optical centre of the lens?$ (1) $210 a$ (2) $Very high, \infty$ (3) $\frac{1}{2}, \frac{f}{2}$ (4) $\frac{1}{4}, \frac{f}{4}$ 422. $Monochromatic light is incident on a glass prism of angle A. If the refractive index of the material of the prism is μ, a ray, incident at an angle θ, on the face AB would get transmitted through the face AC of the prism provided:$ (1) $θ > sin^{- 1} [μ sin (A - sin^{- 1} \frac{1}{μ})]$ (2) $θ < sin^{- 1} [μ sin (A - sin^{- 1} \frac{1}{μ})]$ (3) $θ > cos-1$ (4) $θ < cos-1$ 423. $Match the corresponding entries of Column 1 with Column 2. [Where m is the magnification produced by the mirror] Column 1 (A) m = - 2 (B) m = - \frac{1}{2} (C) m = + 2 (D) m = + \frac{1}{2} Column 2 (p) Convex mirror (q) Concave mirror (r) Real image (s) Virtual image$ (1) $A \to p and s; B \to q and r; C \to q and s; D \to q and r$ (2) $A \to r and s; B \to q and s; C \to q and r; D \to p and s$ (3) $A \to q and r; B \to q and r; C \to q and s; D \to p and s$ (4) $A \to p and r; B \to p and s; C \to p and q; D \to r and s$ 424. $A planoconvex lens has a maximum thickness of 6 cm . When placed on a horizontal table with the curved surface in contact with the table surface, the apparent depth of the bottommost point of the lens is found to be 4 cm . If the lens is inverted such that the plane face of the lens is in contact with the surface of the table, the apparent depth of the center of the plane face is found to be (\frac{17}{4}) cm . The radius of curvature of the lens is$ (1) $68 cm$ (2) $128 cm$ (3) $75 cm$ (4) $34 cm$ 425. $Astigmatism (for a human eye) can be removed by using$ (1) $Concave lens$ (2) $Convex lens$ (3) $Cylindrical lens$ (4) $Prismatic lens$ 426. $A beam ofmonochromatic light is refracted from vacuum into a medium of refractive index 1.5. The wavelength of refracted light will be$ (1) $depend on intensity of refracted light$ (2) $same$ (3) $smaller$ (4) $larger.$ 427. $For a point object, which of the following always produces virtual image in air?$ (1) $Concave mirror$ (2) $Plano-convex lens$ (3) $Convex mirror$ (4) $Biconvex lens$ 428. $The expected graphical representation of the variation of angle of deviation ' δ' with angle of incidence 'i' in a prism is :$ (1) (2) (3) (4) 429. $If yellow light emitted by sodium lamp in Young’s double slit experiment is replaced by monochromatic blue light of the same intensity$ (1) $fringe width will decrease$ (2) $fringe width will increase$ (3) $fringe width will remain unchanged$ (4) $fringes will becomes less intense$ 430. $A thin convex lens (refractive index ) is placed ona plane mirror. When a pin is placed at, such that its real inverted image is formed at itself, as shown in figure. When a liquid of refractive index is put between the lens and the mirror, the pin has to be moved to , such that to get its inverted real image at itself. The value of will be:$ (1) $\frac{4}{3}$ (2) $\frac{3}{2}$ (3) $3$ (4) $2$ 431. $Identify the physical quantity that cannot be measured using spherometer :$ (1) $Radius of curvature of concave surface$ (2) $Specific rotation of liquids$ (3) $Thickness of thin plates$ (4) $Radius of curvature of convex surface$ 432. $and are the parallel sided transparent media of refractive index and respectively. They are arranged as shown in the figure. ray is incident at an angle on the surface of separation of and which is as shown in the figure. After the refraction into the medium , the ray grazes the surface of separation of the media and . Then,$ (1) $\frac{n _{3}}{n _{1}}$ (2) $\frac{n _{1}}{n _{3}}$ (3) $\frac{n _{2}}{n _{3}}$ (4) $\frac{n _{1}}{n _{2}}$ 433. $The critical angle for diamond with respect to air is nearly$ (1) $48.8^{\circ}$ (2) $41.1^{\circ}$ (3) $37.3^{\circ}$ (4) $24.4^{\circ}$ 434. $A defective eye cannot see close objects clearly because their image is formed$ (1) $On the eye lens$ (2) $Between eye lens and retina$ (3) $On the retina$ (4) $Beyond retina$ 435. $In young’s double slit experiment, the fringes width is found to be 0.4 mm. If the whole apparatus is immersed in water of refractive index without disturbing thegeometrical arrangement, the new fringe width will be$ (1) $0.30 mm$ (2) $0.40 mm$ (3) $0.53 mm$ (4) $450 microns.$ 436. $Which of the following statement is incorrect?$ (1) $Dispersion is maximum for violet colour.$ (2) $Red light travels faster than violet light in a medium.$ (3) $In vacuum red light travel faster than others.$ (4) $Refractive index of violet light is higher in flint glass as compared to crown grass.$ 437. $Pick the wrong answer in the context with rainbow.$ (1) $Rainbow is combined effect of dispersion, refraction and reflection of sunlight.$ (2) $When the light rays undergo two internal reflections in a water drop, a secondary rainbow is formed.$ (3) $The order of colours is reversed in the secondary rainbow.$ (4) $An observer can see a rainbow when his front is towards the sun.$ 438. $A convex lens (of focal length 20 cm) and a concave mirror, having their principal axes along the same lines, are kept 80 cm apart from each other. The concave mirror is to the right of the convex lens. When an object is kept at a distance of 30 cm to the left of the convex lens, its image remains at the same position even if the concave mirror is removed. The maximum distance of the object for which this concave mirror, by itself would produce a virtual image would be:$ (1) $30 cm$ (2) $25 cm$ (3) $10 cm$ (4) $20 cm$ 439. $A far sighted man who has lost his spectacles, reads a book by looking through a small hole (3-4 mm) in a sheet of paper. The reason will be$ (1) $Because the hole produces an image of the letters at a longer distance$ (2) $Because in doing so, the focal length of the eye lens is effectively increased$ (3) $Because in doing so, the focal length of the eye lens is effectively decreased$ (4) $None of these$ 440. $A convex lens of focal length 40 cm forms an image of an extended source of light on a photoelectric cell. A current I is produced. The lens is replaced by another convex lens having the same diameter but focal length 20 cm . The photoelectric current now is :$ (1) $\frac{I}{2}$ (2) $4 I$ (3) $2 I$ (4) $I$ 441. $When objects at different distances are seen by the eye, which of the following remains constant$ (1) $The focal length of the eye lens$ (2) $The object distance from the eye lens$ (3) $The radii of curvature of the eye lens$ (4) $The image distance from the eye lens$ 442. $A thin convex lens of focal length 5 cm and a thin concave lens of focal length 4 cm are combined together (without any gap) and this combination has magnification m_{1} when an object is placed 10 cm before the convex lens. Keeping the positions of convex lens and object undisturbed a gap of 1 cm is introduced between the lenses by moving the concave lens away, which lead to a change in magnification of total lens system to m_{2} . The value of (\frac{m _{1}}{m _{2}}) is____.$ (1) $\frac{5}{9}$ (2) $\frac{5}{27}$ (3) $\frac{3}{2}$ (4) $None of the above$ 443. $An object is moving away from concave mirror of focal length f starting from focus. The distance of an object from pole of mirror is x . The correct graph of magnitude of magnification (m) verses distance x is:$ (1) (2) (3) (4) 444. $Image formed on retina of eye is proportional to$ (1) $Size of object$ (2) $Area of object$ (3) $\frac{S i z eo f o bj ec t}{S i z eo f ima g e}$ (4) $\frac{s i z eo f ima g e}{s i z eo f o bj ec t}$ 445. $If there had been one eye of the man, then$ (1) $Image of the object would have been inverted$ (2) $Visible region would have decreased$ (3) $Image would have not been seen three dimensional$ (4) $(b) and (c) both$ 446. $A tall man of height 6 feet, want to see his full image. Then required minimum length of the mirror will be$ (1) $12 feet$ (2) $3 feet$ (3) $6 feet$ (4) $any length.$ 447. $Pick the wrong answer in the context with rainbow.$ (1) $Rainbow is a combined effect of dispersion, refraction and reflection of sunlight.$ (2) $When the light rays undergo two internal reflections in a water drop, a secondary rainbow is formed.$ (3) $The order of colours is reversed in the secondary rainbow.$ (4) $An observer can see a rainbow when his front is towards the sun.$ 448. $A parallel beam of light is incident on a converging lens parallel to its principal axis. As one moves away from the lens on the other side of the principal axis, the intensity of light$ (1) $first decreases and then increases$ (2) $continuously increases$ (3) $continuously decreases$ (4) $first increases and then decreases.$ 449. $In an experiment with a convex lens. The plot of the image distance (v') against the object distance (μ') measured from the focus gives a curve v' μ' = 225. If all the distances are measured in cm. The magnitude of the focal length of the lens is _______ cm.$ 450. $Two light beams fall on a transparent material block at point 1 and 2 with angle and respectively, as shown in figure. After refraction, the beams intersect at point 3 which is exactly on the interface at other end of the block. Given : the distance between 1 and and , where refractive index of the block refractive index of the outside medium , then the thickness of the block is cm.$