JEE Questions for Physics Ray Optics Quiz 14 - MCQExams.com

A convex lens
  • Converges light rays
  • Diverges light rays
  • Form real images always
  • Always forms virtual images
Which of the following graphs is the magnification of a real image against the distance from the focus of a concave mirror?

  • Physics-Ray Optics-86572.png
  • 2)
    Physics-Ray Optics-86573.png

  • Physics-Ray Optics-86574.png

  • Physics-Ray Optics-86575.png
Two plano-concave lenses (1 andof glass of refractive index 1.5 have radii of curvature 25 cm and 20 cm. They are placed in contact with their curved surface towards each other and the space between them is filled with liquid of refractive index 4/3. Then,the combination is
Physics-Ray Optics-86093.png
  • Convex of focal length 70 cm
  • Concave of focal length 70 cm
  • Concave of focal length 66.6 cm
  • Convex of focal length 66.6 cm
Focal length of a converging lens in air is R. If it is dipped in water of refractive index 1.33, then its focal length will be around (Refractive index of lens materials 1.5)
  • R
  • 2R
  • 4R
  • R/2
Focal length of a convex lens of refractive index 1.5 is 2 cm. Focal length of lens when immersed in a liquid of refractive index of 1.25 will be
  • 10 cm
  • 2.5 cm
  • 5 cm
  • 7.5 cm
The focal length of a convex lens depends upon
  • Frequency of the light ray
  • Wavelength of the light ray
  • Both (a) and (b)
  • None of the above
fvand fr are the focal lengths of a convex lens for violet and red light respectively and Fvand Fr are the focal lengths of a concave lens for violet and red light respectively, then
  • fv< fr and Fv> Fr
  • fv< fr and Fv< Fr
  • fv> fr and Fv> Fr
  • fv> fr and Fv< Fr
If a lens is cut into two pieces perpendicular to the principal axis and only one part is used, the intensity of the image
  • Remains same
  • 1/2 times
  • 2 times
  • Infinite
Two thin lenses whose powers are +2D and –4D respectively combine, then the power of combination is
  • –2D
  • +2D
  • –4D
  • +4D
A substance is behaving as convex lens in air and concave in water, then its refractive index is
  • Smaller than air
  • Greater than both air and water
  • Greater than air but less than water
  • Almost equal to water
A concave lens of focal length 20 cm placed in contact with a plane mirror acts as a
  • Convex mirror of focal length 10 cm
  • Concave mirror of focal length 40 cm
  • Concave mirror of focal length 60 cm
  • Concave mirror of focal length 10 cm
A double convex lens of glass of μ = 1.5 has radius of curvature of each of its surface is 0.2 m. The power ofthe lens is
  • + 10 dioptres
  • – 10 dioptres
  • – 5 dioptres
  • + 5 dioptres
A lens of focal power 0.5 D is
  • A convex lens of focal length 0.5 m
  • A concave lens of focal length 0.5 m
  • A convex lens of focal length 2 m
  • A concave lens of focal length 2 m
A double convex thin lens made of glass of refractive index 1.6 has radii of curvature 15 cm each. The focal length of this lens when immersed in a liquid ofrefractive index 1.63 is
  • –407 cm
  • 250 cm
  • 125 cm
  • 25 cm
A lens of power + 2 dioptres is placed in contact with a lens of power –1 diopotre. The combination willbehave like
  • A divergent lens of focal length 50 cm
  • A convergent lens of focal length 50 cm
  • A convergent lens of focal length 100 cm
  • A divergent lens of focal length 100 cm
A candle placed 25 cm from a lens, forms an image on a screen placed 75 cm on the other end of the lens. The focal length and type of the lens should be
  • + 18.75 cm and convex lens
  • – 18.75 cm and concave lens
  • + 20.25 cm and convex lens
  • – 20.25 cm and concave lens
We combined a convex lens of focal length f1 and concave lens of focal lengths f2 and their combined focal length was F. The combination of these lenses willbehave like a concave lens, if
  • f1 > f2
  • f1 < f2
  • f1 = f2
  • f1 ≤ f2
A convex lens has a focal length f. It is cut into two parts along the dotted line as shown in the figure. Thefocal length of each part will be
Physics-Ray Optics-86107.png

  • Physics-Ray Optics-86108.png
  • 2)
    Physics-Ray Optics-86109.png

  • Physics-Ray Optics-86110.png

  • Physics-Ray Optics-86111.png
An object has image thrice of its original size when kept at 8 cm and 16 cm from a convex lens. Focal length of the lens is
  • 8 cm
  • 16 cm
  • Between 8 cm and 16 cm
  • Less than 8 cm
The combination of a convex lens (f = 18 cm) and athin concave lens (f = 9 cm) is
  • A concave lens (f = 18 cm)
  • A convex lens (f = 18 cm)
  • A convex lens (f = 6 cm)
  • A concave lens (f = 6 cm)
The plane faces of two identical piano-convex lenses each having focal length of 40 cm are pressed against each other to form a usual convex lens. The distance from this lens, at which an object must be placed to obtain a real, inverted image with magnification one is
  • 80 cm
  • 40 cm
  • 20 cm
  • 162 cm
The unit of focal power of a lens is
  • Watt
  • Horse power
  • Dioptre
  • Lux
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 theirindividual focal lengths
  • – 75, 50
  • – 10, 15
  • 75, 50
  • – 15, 10
If two + 5 D lenses are mounted at some distance apart, the equivalent power will always be negative ifthe distance is
  • Greater than 40 cm
  • Equal to 40 cm
  • Equal to 10 cm
  • Less than 10 cm
An object is placed 12 cm to the left of a converging lens of focal length 8 cm. Another converging lens of 6 cm focal length is placed at a distance of 30 cm to the right of the first lens. The second lens will produce
  • No image
  • A virtual enlarged image
  • A real enlarged image
  • A real smaller image
The position of final image formed by the given lens combination from the third lens will be at a distance of f1= + 10 cm, f2 = – 10 m, f3 = + 30 cm
Physics-Ray Optics-86119.png
  • 15 cm
  • Infinity
  • 45 cm
  • 30 cm
A point object O is placed in front of a glass rod having spherical end of radius of curvature 30 cm. The imagewould be formed at
Physics-Ray Optics-86121.png
  • 30 cm left
  • Infinity
  • 1 cm to the right
  • 18 cm to the left
Two thin lenses of focal lengths f1 and f2 are in contact. The focal length of this combination is

  • Physics-Ray Optics-86123.png
  • 2)
    Physics-Ray Optics-86124.png

  • Physics-Ray Optics-86125.png

  • Physics-Ray Optics-86126.png
If a parallel beam of white light is incident on a converging lens, the colour which is brought to focus nearest to the lens is
  • Violet
  • Red
  • The mean colour
  • All the colours together
A magnifying glass is to be used at the fixed object distance of 1 inch. If it is to produce an erect image magnified 5 times its focal length should be
  • 0.2 inch
  • 0.8 inch
  • 1.25 inch
  • 5 inch
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 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 of thelens will be
  • 0.4 m
  • 0.2 m
  • 0.1 m
  • 0.75m
A point object is placed at the center of a glass sphere of radius 6 cm and refractive index 1.5. The distance of the virtual image from the surface of the sphere is
  • 2 cm
  • 4 cm
  • –6 cm
  • 12 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 form 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 theobject
  • 20 cm
  • 30 cm
  • 60 cm
  • 80 cm
The focal lengths for violet, green and red light rays are fV, fG and fR respectively. Which of the following isthe true relationship
  • fRGV
  • fV< fG< fR
  • fG< fR< fV
  • fG< fV< fR
The power of an achromatic convergent lens of two lenses is + 2D. The power of convex lens is + 5D. The ratio of dispersive power of convex and concave lenswill be
  • 5 : 3
  • 3 : 5
  • 2 : 5
  • 5 : 2
A combination of two thin convex lenses of focal length 0.3 m and 0.1 m will have minimum spherical and chromatic aberrations if the distance between them is
  • 0.1 m
  • 0.2 m
  • 0.3 m
  • 0.4 m
A point object Ois kept at a distance of OP = u. The radius of curvature of the spherical surface APB is CP = R. The refractive index of the media are n1 and n2 which are as shown in the diagram. Then,
(If n1> n2, image is virtual for all values of u.
(If n2 = 2n1,image is virtual when R > u.
(The image is real for all values of u, n1 and n2.
Here, the correct statement/s is/are
Physics-Ray Optics-86138.png
  • Only (2)
  • Both (and (2)
  • Only (1)
  • (1), (and (3)
The focal length of a plano-convex lens is f and its refractive index is 1.5. It is kept over a plane glass plate with its curved surface touching the glass plate. The gap between the lens and the glass plate is filled by a liquid. As a result, the effective focal length of the combination becomes 2f. Then, the refractive index ofthe liquid is
  • 1.5
  • 2
  • 1.25
  • 1.33
A square card of side length 1 mm is being seen through a magnifying lens of focal length 10 cm. The card is placed at a distance of 9 cm from the lens. The apparent area of the card through the lens is
  • 1 cm2
  • 0.81 cm2
  • 0.27 cm2
  • 0.60 cm2
A bi-convex lens is formed with two thin piano-convex lenses as shown in the figure. Refractive index n of the first lens is 1.5 and that of the second lens is 1.2. Both the curved surfaces are of the same radius of curvature R = 14 cm. For this bi-convex lens, for an object distance of 40 cm, the image distance will be
Physics-Ray Optics-86141.png
  • –280.0 cm
  • 40.0 cm
  • 21.5 cm
  • 13.3 cm
An object 2.4 m in front of a lens forms a sharp image on a film 12 cm behind the lens. A glass plate 1 cm thick, of refractive index 1.50 is interposed between lens and film with its plane faces parallel to film. At what distance (from lens) should object shifted to be insharp focus on film
  • 7.2 m
  • 2.4 m
  • 3.2 m
  • 5.6 m
Which source is associated with a line emission spectrum
  • Electric fire
  • Neon street sign
  • Red traffic light
  • Sun
Formula for dispersive power is (where symbols havetheir usual meanings)
or
If the refractive indices of crown glass for red, yellow and violet colours are respectively µr, µy and µv; then the dispersive power of this glass would be

  • Physics-Ray Optics-86144.png
  • 2)
    Physics-Ray Optics-86145.png

  • Physics-Ray Optics-86146.png

  • Physics-Ray Optics-86147.png
The critical angle between an equilateral prism and air is 45°. If the incident ray is perpendicular to the refracting surface, then
  • After deviation it will emerge from the second refracting surface
  • It is totally reflected on the second surface and emerges out perpendicularly from third surface in air
  • It is totally reflected from the second and third refracting surfaces and finally emerges out from the first surface
  • It is totally reflected from all the three sides of prism and never emerges out
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'
Solar spectrum is an example for
  • Band absorption spectrum
  • Line absorption spectrum
  • Line emission spectrum
  • Continuous emission spectrum
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
Angle of minimum deviation for a prism of refractive index 1.5 is equal to the angle of prism. The angle of prism is (cos 41° = 0.75)
  • 62°
  • 41°
  • 82°
  • 31°
0:0:1


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