JEE Questions for Physics Ray Optics Quiz 5 - MCQExams.com

Which of the following is not the case with the image formed by a concave lens?
  • It may be erect or inverted
  • It may be magnified or diminished
  • It may be real or virtual
  • Real image may be between the pole and focus or beyond focus
A prism of angle 30° is silvered at one side. A ray of light incident at an angle 45° is reflected back from the silvered surface. The refractive index is

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  • 2)
    Physics-Ray Optics-85475.png

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  • Physics-Ray Optics-85477.png
A wire mesh consisting of very small squares is viewed at a distance of 8 cm through a magnifying converging lens of focal length 10 cm, kept close to the eye. The magnification produced by the lens is
  • 5
  • 8
  • 10
  • 20
A lens is made of flint glass (refractive index = 1.5). When the lens is immersed in a liquid of refractive index 1.25, the focal length
  • increase by a factor of 1.25
  • increases by a factor of 2.5
  • increases by a factor of 1.2
  • decreases by a factor of 1.2
White light is incident on one of the refracting surfaces of a prism of angle 5°. If the refractive indices for red and blue colours are 1.641 and 1.659 respectively, the angular separation between these two colours when they emerge out of the prism is
  • 0.9°
  • 0.09°
  • 1.8°
  • 1.2°
For a given lens, the magnification was found to be twice as large as when the object was 0 15 m distant from it as when the distance was 0.2 m. The focal length of the lens is
  • 1.5 m
  • 0.20 m
  • 0.10 m
  • 0.05 m
A thin prism P1 with angle 4° made from a glass refractive index 1.54 is combined with another thin prism P2 made from glass of refractive index 1.72 to produce dispersion without deviation. The angle of the prism P2 is
  • 5.33°
  • 4°
  • 3°
  • 2.6°
A ray of light incident normally on one face of a right angled isoscales prism. It them grazes the hypotenuse. The refractive index of the material of the prism is
  • 1.33
  • 1.414
  • 1.5
  • 1.732
A prism of a certain angles deviates the red and blue rays by 8° and 12° respectively. Another prism of the same angle deviates the red and blue rays by 10°, respectively. The prisms are small angled and made of different materials. The dispersive powers of the materials of the prisms are in the ratio
  • 5 : 6
  • 9 : 11
  • 6 : 5
  • 11 : 9
A symmetric double convex lens is cut in two equal parts by a plane perpendicular to the principle axis. If the power of the original lens is 4D, the power of a cut lens will be
  • 2D
  • 3D
  • 4D
  • 5D
A convex lens is placed between object and a screen. The size of object is 3 cm and an image of height 9 cm is obtained on the screen. When the lens is displaced to a new position, what will be the size of image on the screen?
  • 2 cm
  • 6 cm
  • 4 cm
  • 1 cm
The refractive index of the material of a double convex lens is 1.5 and its focal length is 5 cm. If the radii of curvature are equal, the value of the radius of curvature (in cm) is
  • 5.0
  • 6.5
  • 8.0
  • 9.5
The least angle of deviation for a glass prism is equal to its refracting angle. The refractive index of glass is 1.5. Then the angle of prism is

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    Physics-Ray Optics-85479.png

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Lenses of power 3 D and – 5 D are combined to from a compound lens. An object is placed at a distance of 50 cm from this lens. Its image will be formed at a distance from the lens, will be
  • 25 cm
  • 20 cm
  • 30 cm
  • 40 cm
A plano-convex lens of refractive index 1.5 and radius of curvature 30 cm is silvered at the curved surface. Now, this lens has been used to from the image of an object. At what distance from this lens, an object be placed in order to have a real image of the size of the object?
  • 20 cm
  • 30 cm
  • 60 cm
  • 80 cm
A point object is placed at distance of 20 cm from a thin plano-convex lens of focal length 15 cm. The plane surface of the lens is now silvered. The image created by the system is at
Physics-Ray Optics-85482.png
  • 60 cm to the left of the system
  • 60 cm to the right of the system
  • 12 cm to the left of the system
  • 12 cm to the right of the system
The graph between object distance u and image distance v for lens is given below. The focal length of the lens is
Physics-Ray Optics-85483.png
  • 5 ± 0.1
  • 5 ± 0.05
  • 0.5 ± 0.1
  • 0.5 ± 0.05
Which of the following is true for rays coming form infinity?
Physics-Ray Optics-85484.png
  • Two images are formed
  • Continuous image is formed between focal points of upper and lower lens
  • One image is formed
  • None of the above
A convex lens made up of a material of refractive index µ1 is immersed in a medium of refractive index µ2 as shown in the figure. The relation between µ1 and µ2 is
Physics-Ray Optics-85485.png
  • µ1 < µ2
  • µ1 > µ2
  • µ1 = µ2
  • µ1 = √µ2
If a flint lens glass of dispersive power 0.066 renders achromatic to a convex lens of crown glass of focal length 60 cm and dispersive power 0.033, then its focal length is
  • – 60 cm
  • + 60 cm
  • – 120 cm
  • + 120 cm
A thin plano-convex lens acts like a concave mirror of focal length 0.2 m when silvered from its plane surface. The refractive index of the material of the lens is 1.5. The radius of curvature of the convex surface the lens will be
  • 0.1 m
  • 0.75 m
  • 0.4 m
  • 0.2 m
Dispersive power depends on the following
  • material of the prism
  • shape of the prism
  • size of the prism
  • size, shape and material of the prism
Two thin lenses of focal lengths f1 and f2 are placed in contact with each other. The focal length of the combination is

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    Physics-Ray Optics-85487.png

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A convex lens is in contact with concave lens. The magnitude of the ratio of their focal length is 2/3. Their equivalent focal length is 30 cm. What are their individual focal lengths?
  • – 75, 50
  • –10, 15
  • 75, 50
  • –15, 10
A thin glass (refractive index 1.lens has optical power of - 5 D in air. Its optical power in a liquid medium with refractive index 1.6 will be
  • 1 D
  • – 1D
  • 25 D
  • – 25 D
Refractive index of glass with respect to medium is 4/3. If the differences between velocities of light in medium and glass is 6.25 × 107 ms-1, then velocity of light in medium is
  • 2.5 × 108 ms-1
  • 0.125 × 108 ms-1
  • 1.5 × 108 ms-1
  • 3 × 108 ms-1
The focal length of an equi-convex lens is greater than the radius of curvature of any of the surfaces. Then, the refractive index of the material of the lens is
  • greater than zero but less than 1.5
  • greater than 1.5 but less than 2.0
  • greater than 2.0 but less than 2.5
  • greater than 2.5 but less than 2.0
An electric bulb of luminous intensity I is suspended at a height h from centre of the table having a circular surface diameter 2 r. The illuminance at centre of circular dis will be
  • I/r2
  • I/r
  • I/h2
  • I/h
At what distance should a book be placed from a 50 Cd bulb so that the illuminance on the book becomes 2 lmm–2 ?
  • 1 m
  • 5 m
  • 10 m
  • 50 m
A point source of 100 candela is held 5m above a sheet of blotting paper which reflects 75% of light incident upon it. The illuminance of blotting paper is
  • 4 phot
  • 4 lux
  • 3 phot
  • 3 lux
An isotropic source of 2 candela produces a light flux equal to
  • 2 π lumen
  • 4 π lumen
  • 6 π lumen
  • 8 π lumen
A lamp rated at 100 Cd hangs over the middle of a round table with a diameter of 3 metre at a height of 2 metre. It is replaced by a lamp of 25 Cd and the distance to the table is changed so that the illumination at the centre of the table remains as before. The illumination at the edge of the table becomes X time the original. Then X is

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  • 2)
    Physics-Ray Optics-85500.png

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A screen is illuminated by two point sources A and B. Another source (sends a parallel beam of light towards P on the screen. The lines AP, BP and CP are 3 m, 1.5 m and 1.5 m respectively, Fig. The radiant powers of sources A and B are 90 W and 180 W resp. The beam coming from C is of intensity 20 W/m2. The intensity at point P on screen due to source a will be
Physics-Ray Optics-85504.png

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    Physics-Ray Optics-85506.png

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The illuminance of a surface 2 m away from a point source is 4 W/m2. It will be 2 W/m2 when the distance of the point from the source is

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  • 2)
    Physics-Ray Optics-85511.png

  • Physics-Ray Optics-85512.png

  • Physics-Ray Optics-85513.png
The frequency of e.m. wave which is best suited to observe a particle of radii 3 × 10–4 cm is of the order of
  • 1015
  • 1013
  • 1014
  • 1012
If the speed of red light is denoted by Vr and the speed of violet light Vu then for vacuum
  • Vr > Vu
  • Vr = Vu
  • Vr < Vu
  • None of these
A plane mirror is approaching you at 5 cm. per second. You can see your image in it. At what speed will your image approach you?
  • 10 cm per sec
  • 5 cm per sec
  • 20 cm per sec
  • 15 cm per sec
A convex mirror of focal length f produces an image (1/n) th of the size of the object. The distance of the object from the mirror is
  • (n –f
  • f/n
  • (n +f
  • nf
When light wave suffers reflection, at the interface between air and glass, the change of phase in the reflected wave is equal to
  • zero
  • 2 π radian
  • π radian
  • 3 λ radian
A thin convergent glass lens (µg = 1.has a power of + 5.0 D. When this lens is immersed in a liquid of refractive index µ, it acts as a divergent lens of focal length 100 cm. The value of µ must be
  • 4/3
  • 5/3
  • 5/4
  • 6/5
A prism of refraction angle 60º has minimum angle of deviation of 30º. What must be the angle of incidence for this case?
  • 0º
  • 90º
  • 45º
  • 30º
Yellow light is refracted through a prism producing minimum deviation. If i1 and i2 denote the angle of incidence and emergence for this prism, then
  • ii = i2
  • ii > i2
  • ii < i2
  • ii + i2 = 90o
When white light passes through a dispersive medium, it breaks up into various colours. Which of the following statements is true?
  • Velocity of light for violet is greater than the velocity of light for red colors
  • Velocity of light for violet is less than the velocity of light for red
  • Velocity of light is the same for all colours
  • Velocity of light for different colours has nothing to do with the phenomenon of dispersion
Emission of light stops as the incident light is cut off in
  • Phosphorescence
  • Fluorescence
  • Luminescence
  • Efforescence
Indicate the correct statement in the following
  • The dispersive power depends upon the angle of prism
  • The angular dispersion depends upon the angle of the prism
  • The angular dispersion does not depend upon the dispersive power
  • The dispersive power in vacuum is one
The refracting angle of a prism is A and the refractive index is cot (A/2). What is angle of minimum deviation?
  • (180º - A)
  • (180º - 2A)
  • (90º - A)
  • (90º - 2A)
Two lenses of focal lengths + 10 cm and – 15 cm when put in contact behave like convexlens. They will have zero longitudinal chromatic aberration, if ratio of dispersive powers is
  • + 3/2
  • + 2/3
  • – 3/2
  • – 2/3
A person wants to see two pillars distant 11 km separately. The distance between the pillars be approximately
  • 3.2 m
  • 1 m
  • 0.25 m
  • 0.5 m
Magnifying power of an astronomical telescope for normal vision with usual notation is

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    Physics-Ray Optics-85526.png

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A film projector magnifies a 100 sq cm film strip on a screen. If the linear magnification is 4, the area of magnified film on the screen is
  • 1600 sq. cm
  • 400 sq. cm
  • 25 sq. cm
  • 250 sq. cm
0:0:1


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