JEE Questions for Physics Ray Optics Quiz 25 - MCQExams.com

fvand fr are the focal lengths of a convex lens for violet and red light respectively and Fv and Fr are the focal lengths of a concave lens for violet and red light respectively, then
  • fv< fr and Fv> Fr
  • fv< frand Fv< Fr
  • fv> frand Fv> Fr
  • fv> frand Fv< Fr
A convex lens of focal length f produces an image 1/n times than that of the size of the object. The distance of the object from the lens is
  • nf
  • f/n
  • –(n +f
  • (n –f
A combination of two thin lenses of the same material with focal lengths f1 and f2, arranged on a common axis minimizes chromatic aberration, if the distance between them is

  • Physics-Ray Optics-86895.png
  • 2)
    Physics-Ray Optics-86896.png

  • Physics-Ray Optics-86897.png

  • Physics-Ray Optics-86898.png
The focal length of the field lens (which is an achromatic combination of two lenses) of telescope is 90 cm. The dispersive powers of the two lenses in the combination are 0.024 and 0.036. The focal lengths of two lenses are
  • 30 cm and 60 cm
  • 30 cm and – 45 cm
  • 45 cm and 90 cm
  • 15 cm and 45 cm
If the focal length of a double convex lens for red lightis fR, its focal length for the violet light is
  • fR
  • Greater than fR
  • Less than fR
  • 2 fR
A thin equiconvex lens is made of glass of refractive index 1.5 and its focal length is 0.2 m, if it acts as a concave lens of 0.5 m focal length when dipped in a liquid, the refractive index of the liquid is
  • 17/8
  • 15/8
  • 13/8
  • 9/8
Chromatic aberration of lens can be corrected by
  • Reducing its aperature
  • Proper polishing of its two surfaces
  • Suitably combining it with another lens
  • Providing different suitable curvature to its two surfaces
An object is placed at a distance of 10 cm from a convex lens of power 5D. Find the position of the image
  • –20 cm
  • 30 cm
  • 20 cm
  • –30 cm
In a plano-convex lens the radius of curvature of the convex lens is 10 cm. If the plane side is polished, then the focal length will be (Refractive index = 1.5)
  • 10.5 cm
  • 10 cm
  • 5.5 cm
  • 5 cm
The focal length of a convex lens is 10 cm and its refractive index is 1.5. If the radius of curvature of one surface is 7.5 cm, the radius of curvature of the second surface will be
  • 7.5 cm
  • 15.0 cm
  • 75 cm
  • 5.0 cm
Figure given below shows a beam of light converging at point P. When a concave lens of focal length 16 cm is introduced in the path of the beam at a place O shown by dotted line such that OP becomes the axis of the lens, the beam converges at a distance x from the lens. The value x will be equal to
Physics-Ray Optics-86906.png
  • 12 cm
  • 24 cm
  • 36 cm
  • 48 cm
When light rays from the sun fall on a convex lens alonga direction parallel to its axis
  • Focal length for all colours is the same
  • Focal length for violet colour is the shortest
  • Focal length for yellow colour is the longest
  • Focal length for red colour is the shortest
A convex lens is made up of three different materials as shown in the figure. For a point object placed on its axis, the number of images formed are
Physics-Ray Optics-86908.png
  • 1
  • 5
  • 4
  • 3
The dispersive power of the material of lens of focallength 20 cm is 0.08. The longitudinal chromatic aberration of the lens is
  • 0.08 cm
  • 0.08/20 cm
  • 1.6 cm
  • 0.16 cm
A convex lens is dipped in a liquid whose refractiveindex is equal to the refractive index of the lens. Then its focal length will
  • Become infinite
  • Become small, but non-zero
  • Remain unchanged
  • Become zero
The sun makes 0.5° angle on earth surface. Its image ismade by convex lens of 50 cm focal length. The diameter of the image will be
  • 5 mm
  • 4.36 mm
  • 7 mm
  • None of these
The chromatic aberration in lenses becomes due to
  • Dissimilarity of main axis of rays
  • Dissimilarity of radii of curvature
  • Variation of focal length of lenses with wavelength
  • None of the above
If aperture of lens is halved then image will be
  • No effect on size
  • Intensity of image decreases
  • Both (a) and (b)
  • None of the above
When the convergent nature of a convex lens will beless as compared with air
  • In water
  • In oil
  • In both (a) and (b)
  • None of these
An object placed 10 cm in front of a lens has an image 20 cm behind the lens. What is the power of the lens (in dioptres)?
  • 1.5
  • 3.0
  • –15.0
  • +15.0
A beam of parallel rays is brought to a focus by a plano-convex lens. A thin concave lens of the same focal length is joined to the first lens. The effect of this is
  • The focal point shifts away from the lens by a small distance
  • The focus remains undisturbed
  • The focus shifts to infinity
  • The focal point shifts towards the lens by a small distance
In order to obtain a real image of magnification 2 using a converging lens of focal length 20 cm, where should an object be placed
  • 50 cm
  • 30 cm
  • –50 cm
  • –30 cm
A double convex lens (R1 = R2 = 10 cm) (µ = 1.having focal length equal to the focal length of a concave mirror. The radius of curvature of the concave mirror is
  • 10 cm
  • 20 cm
  • 40 cm
  • 15 cm
The radius of the convex surface of plano-convex lens is 20 cm and the refractive index of the material of the lens is 1.5. The focal length of the lens is
  • 30 cm
  • 50 cm
  • 20 cm
  • 40 cm
When a lens of refractive index n1 is placed in a liquid of refractive index n2, the lens looks to be disappeared only, if
  • n1 = n2/2
  • n1 = 3n2/4
  • n1 = n2
  • n1 = 5n2/4
The power of a biconvex lens is 10 dioptre and the radius of curvature of each surface is 10 cm. Then the refractive index of the material of the lens is
  • 3/2
  • 4/3
  • 9/8
  • 5/3
  • 3/4
A converging beam of rays is incident on a diverging lens. Having passed through 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 meet will move 5 cm closer to the lens. The focal length of the lens is
  • –30 cm
  • 5 cm
  • –10 cm
  • 20 cm
A biconvex lens has a radius of curvature of magnitude 20 cm. Which one of the following options describe best the image formed of an object of height 2 cm placed 30 cm from the lens
  • Real, inverted, height =1 cm
  • Virtual, upright, height =1 cm
  • Virtual, upright, height = 0.5 cm
  • Real, inverted, height = 4 cm
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
  • Equal to that of glass
  • Less than one
  • Greater than that of glass
  • Less than that of glass
When white light passes through a glass prism, one gets spectrum on the other side of the prism. In the emergent beam, the ray which is deviating least is
or
Deviation by a prism is lowest for
  • Violet ray
  • Green ray
  • Red ray
  • Yellow ray
We use flint glass prism to disperse polychromatic light because light of different colours
  • Travel with same speed
  • Travel with same speed but deviate differently due to the shape of the prism
  • Have different anisotropic properties while travelling through the prism
  • Travel with different speeds
A prism (µ = 1.has the refracting angle of 30°. The deviation of a monochromatic ray incident normally on its one surface will be (sin 48° 36\' = 0.75)
  • 18° 36'
  • 20° 30'
  • 18°
  • 22°1'
Fraunhoffer lines are obtained in
  • Solar spectrum
  • The spectrum obtained from neon lamp
  • Spectrum from a discharge tube
  • None of the above
A spectrum is formed by a prism of dispersive power \'ω\'. If the angle of deviation is \'δ\', then the angular dispersion is
  • ω/δ
  • δ/ω
  • 1/ωδ
  • ωδ
Light from sodium lamp is passed through cold sodium vapours, the spectrum of transmitted light consists of
  • A line at 5890 Å
  • A line at 5896 Å
  • Sodium doublet lines
  • No spectral features
The refractive index of a prism for a monochromatic wave is √2 and its refracting angle is 60°. For minimum deviation, the angle of incidence will be
  • 30°
  • 45°
  • 60°
  • 75°
The ratio of angle of minimum deviation of a prism in air and when dipped in water will be (aµg = 3 / 2 and aµw = 4/ 3)
  • 1/8
  • 1/2
  • 3/4
  • 1/4
A light ray is incident by grazing one of the face of a prism and after refraction ray does not emerge out, what should be the angle of prism while critical angle is C
  • Equal to 2C
  • Less than 2C
  • More than 2C
  • None of these
The spectrum of light emitted by a glowing solid is
  • Continuous spectrum
  • Line spectrum
  • Band spectrum
  • Absorption spectrum
Light rays from a source are incident on a glass prism of index of refraction µ and angle of prism α. At near normal incidence, the angle of deviation of the emerging rays is
  • (µ– 2)α
  • (µ– 1)α
  • (µ + 1)α
  • (µ + 2)α
Which of the following element was discovered by study of Fraunhoffer lines?
  • Hydrogen
  • Oxygen
  • Helium
  • Ozone
Three prisms of crown glass, each have angle of prism 9° and two prisms of flint glass are used to make direct vision spectroscope. What will be the angle of flint glass prisms if µ for flint is 1.60 and µ for crown glass is 1.53?
  • 11.9°
  • 16.0°
  • 15.3°
  • 9.11°
The angle of minimum deviation for a prism is 40° and the angle of the prism is 60°. The angle of incidence in this position will be
  • 30°
  • 60°
  • 50°
  • 100°
The light ray is incidence at angle of 60° on a prism of angle 45°. When the light ray falls on the other surface at 90°, the refractive index of the material of prism µ and the angle of deviation δ are given

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    Physics-Ray Optics-86943.png

  • Physics-Ray Optics-86944.png

  • Physics-Ray Optics-86945.png
The angle of minimum deviation measured with a prism is 30° and the angle of prism is 60°. The refractive index of prism material is
  • √2
  • 2
  • 3/2
  • 4/3
An achromatic prism is made by combining two prisms
P1 (µv = 1.523, µ8 = 1.and
P2(µv = 1.666, µr = 1.;
where µ represents the refractive index. If the angle of the prism P1 is 10°, then the angle of the prism P2will be
  • 5°
  • 7.8°
  • 10.6°
  • 20°
30°Angle of a prism is 30° and its refractive index is √2 and one of the surface is silvered. At what angle of incidence, a ray should be incident on one surface so that after reflection from the silvered surface, it retracesits path
  • 30°
  • 60°
  • 45°

  • Physics-Ray Optics-86950.png
When sunlight is scattered by atmospheric atoms and molecules, the amount of scattering of light of wavelength 440 nm is A. The amount of scattering for the light of wavelength 660 nm is approximately
  • 4/9 A
  • 2.25 A
  • 1.5 A
  • 0.66 A
  • A/5
In the measurement of the angle of a prism using a spectrometer, the readings of first reflected image are VernierI : 320° 40\'; Vernier II : 140° 30\' and those of the second reflected image are Vernier I : 80° 38\'; Vernier II : 260° 24\'. Then the angle of the prism is
  • 59° 58'
  • 59° 56'
  • 60° 2'
  • 60° 4'
  • 60° 0'
What will be the colour of sky as seen from the earth, if there were no atmosphere
  • Black
  • Blue
  • Orange
  • Red
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