JEE Questions for Physics Ray Optics Quiz 7 - MCQExams.com

A ray PQ incident on the refracting face BA is refracted in the prism BAC as shown in the figure, and emerges from the other refracting face AC as RS, such that AQ = AR. If the angle of prism A = 60° and the refractive index of the material of prism is √3 , then the angle of deviation of the ray is
Physics-Ray Optics-85610.png
  • 60°
  • 45°
  • 30°
  • None of these
In an experiment to determine the focal length (f ) of a concave mirror by the u-v method, a student places the object pin A on the principal axis at a distance x from the pole P. The student looks at the pin and its inverted image from a distance keeping his/her eye in line with PA. When the student shifts his/her eye towards left, the image appears to the right of the object pin.Then,
  • x < f
  • f < x < 2f
  • x = 2f
  • x > 2f
The position of final image formed by the given lens combination from the third lens will be at a distance of
[ f1 = + 10cm , f2 = – 10cm , f3 = + 30cm ]
Physics-Ray Optics-85612.png
  • 15 cm
  • infinity
  • 45 cm
  • 30 cm
  • 35 cm
The refractive index of glass is 1.520 for red light and 1.525 for blue light. Let D1 and D2 be angles of minimum deviation for red and blue light respectively in a prism of this glass. Then,
  • D1 < D2
  • D1 = D2
  • D1 can be less than or greater than D2 depending upon the angle of prism
  • D1 > D2
The plane faces of two identical piano-convex lenses each having a focal length of 50 cm are placed against each other to form a usual bi-convex lens. The distance from this lens combination at which an object must be placed to obtain a real, inverted image which has the same size as the object is
  • 50 cm
  • 25 cm
  • 100 cm
  • 40 cm
  • 125 cm
A beam of parallel rays is brought to 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 focus shifts to infinity
  • the focal point shifts towards the lens by a small distance
  • the focal point shifts away from the lens by a small distance
  • the focus remains undisturbed
The two surfaces of a biconvex lens has same radii of curvatures. This lens is made of glass of refractive index 1.5 and has a focal length 10 cm in air. The lens is cut into two equal halves along a plane perpendicular to its principal axis to yield two plano-convex lenses. The two pieces are glued such that the convex surfaces touch each other. If this combination lens is immersed in water (refractive index = 4/3), its focal length (in cm) is
  • 5
  • 10
  • 20
  • 40
Which of the following is a wrong statement?
  • D =1/ f where, f is the focal length and D is called the refractive power of a lens
  • Power is expressed in a dioptre when f is in metre
  • Power is expressed in diopter and does not depend on the system of unit used to measure f
  • D is positive for convergent lens and negative for divergent lens
A given ray of light suffers minimum deviation in an equilateral prism P. Additional prisms Q and of identical shape and material are now added to P, as shown in the figure. The ray will stiffer
Physics-Ray Optics-85613.png
  • same deviation
  • greater deviation
  • total internal reflection
  • no deviation
In Michelson’s experiment, distance between two fixed mirrors is increased to twice. How will the speed of octagonal mirror be adjusted for continuous image of the source?
  • Twice
  • Half
  • Same
  • Four times
Figure shows two parallel rays incident on a mirror. They are reflected as parallel rays as shown in the same figure. What is the nature of the mirror?
Physics-Ray Optics-85614.png
  • Plane
  • Concave
  • Convex
  • Parabolic
Two lenses of power 2.5 D and 1.5 D are joined together. The power of the new lens formed is
  • 1.0 D
  • 5/3 D
  • 3/5 D
  • 4.0 D
A fish 10 cm long is 4 cm under the water level. Its length when viewed vertically above will be
  • 10 cm
  • 3 cm
  • 7.5 cm
  • 8 cm
A well cut diamond appears bright because
  • It emits light
  • It is radioactive
  • of total internal reflection
  • It has high density
An air bubble in a glass slab (µ = 1.is 5 cm deep when viewed from one face and 2 cm deep when viewed from the opposite face. The thickness of the slab is
  • 10.5 cm
  • 7 cm
  • 10 cm
  • 7.5 cm
A ray of light travelling inside a rectangular glass block of refractive index √2 is incident on the glass-air surface at an angle of incidence of 45º. The refractive index of air is one. Under these conditions, the ray
  • will emerge into the air without any deviation
  • will be reflected back into the glass
  • will be absorbed
  • will emerge into the air with an angle of refraction equal to 90º
A ray of light passes from vacuum into a medium of refractive index µ, the angle of incidence is found to be twice the angle of refraction. Then the angle of incidence is
  • cos–1 (µ/2)
  • 2cos–1 (µ/2)
  • 2sin–1 (µ)
  • 2sin–1 (µ/2)
A convex lens of focal length f produces a real image n times the size of an object, then the distance of the object from the lens is
  • (n –f
  • (n +f

  • Physics-Ray Optics-85617.png

  • Physics-Ray Optics-85618.png
An object is placed at a distance of f/2 from a convex lens. The image will be
  • at one of the foci, virtual and double its size
  • 2)
    Physics-Ray Optics-85620.png
  • at 2f, virtual and erect
  • at f, real and inverted
A lens of power +2 diopter is placed in contact with a lens of Power -1 diopter. The combination will behave like
  • a convergent lens of focal length 50 cm
  • a divergent lens of focal length 100 cm
  • a convergent lens of focal length 100 cm
  • a convergent lens of focal length 200 cm
A convex lens of crown glass (µ = 1.will act as a diverging lens if it is immersed in
  • water (µ = 1.33)
  • medium (µ = 1.525)
  • carbon disulfide (µ = 1.
  • None of the above
A ray of light, incident on one face of an equilateral prism undergoes total internal reflection at another face. If the refractive index of the material of prism is √2 , then angle of refraction (r2) at another face will be
  • 15o
  • 30o
  • 45o
  • sin-1(√2 sin 15o)
A point source of light is placed 4 m below the surface of water of refractive index 5/3. The minimum diameter of a disc, which should be placed over source, on surface of water to cut off all light coming out of water is
  • 1 m
  • 4 m
  • 3 m
  • 6 m
When a ray of light enters a medium of refractive index µ, then it is observed that the angle of refraction is half the angle of incidence. The value of angle of incidence will be

  • Physics-Ray Optics-85625.png
  • 2)
    Physics-Ray Optics-85626.png

  • Physics-Ray Optics-85627.png

  • Physics-Ray Optics-85628.png
An under water swimmer is at a depth of 12 m below the surface of water. A bird is at a height of 18 m from the surface of water, directly above his eyes. For the swimmer, the bird appears to be at a distance X from the surface of water. (Refractive index of water is 4/3). The value of X is
  • 24 m
  • 12 m
  • 18 m
  • 9 m
Fraunhofer spectrum is a
  • line absorption spectrum
  • band absorption spectrum
  • line emission spectrum
  • band emission spectrum
An equilateral prism is placed on the prism table of a spectrometer in the position of minimum deviation. If the angle of incidence is 60º, the angle of deviation of the ray is
  • 90º
  • 60º
  • 45º
  • 30º
Three glass prisms A, B and C of the same refractive index are placed in contact with eachother as shown in Fig with no air gap between the prisms. A monochromatic ray of light OP passes through the prism assembly and emerges as QR. The condition of minimum deviation is satisfied in the prism.
Physics-Ray Optics-85632.png
  • A and C
  • B and C
  • A and B
  • A, B and C
A ray falls on a prism ABC (AB = BC) and travels as shown in Fig. The minimum refractive index of the prism material should be
Physics-Ray Optics-85633.png

  • Physics-Ray Optics-85634.png
  • 2)
    Physics-Ray Optics-85635.png

  • Physics-Ray Optics-85636.png

  • Physics-Ray Optics-85637.png
In a thin prism of glass g (aµg = 1., which of the following relations between the angle of minimum deviation δm and angle of refraction r will be correct?
  • δm = r
  • δm = 1.5 r
  • δm = 2r
  • δm = r/2
If a monochromatic green light is incident on a phosphorescent substance, the colour of light emitted by it is
  • Same green colour
  • Nearer to red in the spectrum of white light
  • Nearer to violet in the spectrum of white light
  • White colour
A ray of light is incident at an angle of 60º on one face of a prism of angle 30º. The emergent ray of light makes an angle of 30º with incident ray. The angle made by emergent ray with second face of prism will be
  • 0º
  • 90º
  • 45º
  • 30º
Two lenses in contact form an achromatic lens. Their focal lengths are in the ratio 2:3. Their dispersive powers must be in the ratio of
  • 1 : 3
  • 3 : 3
  • 3 : 2
  • 3 : 1
A combination is made of two lenses of focal length f and f’ in contact, the dispersive powers of the materials of the lenses are ω and ω’. The combination is achromatic, when

  • Physics-Ray Optics-85642.png
  • 2)
    Physics-Ray Optics-85643.png

  • Physics-Ray Optics-85644.png

  • Physics-Ray Optics-85645.png
Two thin lenses of focal lengths f1 and f2 are made of materials of dispersive powers ω1 and ω2 respectively. The lenses are kept in contact. The combination will show no chromatic aberration, if

  • Physics-Ray Optics-85647.png
  • 2)
    Physics-Ray Optics-85648.png

  • Physics-Ray Optics-85649.png

  • Physics-Ray Optics-85650.png
What is longitudinal spherical aberration in case of a lens which focusses central rays at 20.3 cm and marginal rays at 20.1 cm.
  • 0.2 cm
  • 0.4 cm
  • Zero
  • None of these
Two convex lenses L1 and L2 are coaxially placed with respect to each other as shown in Fig. which also shows the position F1 and F2 of their focal points. An object OP placed in front of the lens L1 forms an image AB close to F2 between F2C2. The final image as seen by the eye will be formed
  • inverted and will be beyond the object at a distance greater than C1 C2
  • inverted and will be formed at infinity
  • erect and will be formed between C1 and C2
  • inverted and will be formed between C1 and C2
The focal lengths of objective and eye lens of an astronomical telescope are respectively 2 meter and 5 cm. Final image is formed at (i) least distance of distinct vision (ii) infinity. Magnifying power in two cases will be
  • – 48, – 40
  • – 40, – 48
  • – 40, + 48
  • – 48, + 40
The focal length of a convex lens is 2.5 cm. Its magnifying power will be 25
  • 25
  • 52
  • 11
  • 1.1
The f number of a camera lens is 4.5. Which of the following statements is correct?
  • The focal length of the lens is 4.5 cm
  • It is the reciprocal of the focal length expressed in metres
  • The ratio of focal length of lens to the aperture is 4.5
  • The aperture of the lens is 4.5 cm
How should people wearing spectacles work with a microscope?
  • They should keep on wearing their spectacles
  • They should take off their spectacles
  • They may keep on wearing or take off their spectacles, it makes no difference
  • They cannot use a microscope at al
A person cannot see the objects beyond 100 cm. The power of a lens to correct this vision will be
  • + 2 D
  • – 1 D
  • + 5 D
  • 0.5 D
A person cannot see an object lying beyond 80 cm, whereas a normal person can easily see the object distant 160 cm. The focal length and nature of the lens used to rectify this defect will be
  • -160 cm, concave
  • -160 cm, convex
  • 60 cm, concave
  • 160 cm, convex
A lens is placed between a source of light and a wall. It forms images of area A1 and A2 on the wall, for its two different positions. The area of the source obtained is

  • Physics-Ray Optics-85657.png
  • 2)
    Physics-Ray Optics-85658.png

  • Physics-Ray Optics-85659.png

  • Physics-Ray Optics-85660.png
A plane mirror produces a magnification of
  • – 1
  • + 1
  • zero
  • between 0 and + ∞
The astronomical telescope consists of objective and eye-piece. The focal length of the objective is
  • equal to that of the eye piece
  • greater than that of eye piece
  • shorter than that of eye piece
  • five times shorter than that of the eye piece
A convex lens has a focal length f. It is cut into two parts along a line perpendicular to principal axis. The focal length of each part will be
  • 3/2 f
  • 2f
  • f/2
  • f
A given ray of light suffers minimum deviation in an equilateral prism P. Additional prisms Q and R of identical shape and of the same material as P are now added as shown in Fig. The ray will now suffer
Physics-Ray Optics-85665.png
  • greater deviation
  • no deviation
  • same deviation as before
  • total internal reflection
Critical angle for light going from medium (i) to (ii) is Ө. The speed of light in medium (i) is u. Then speed in medium (ii) is
  • u (1 – cos Ө)
  • u/sin Ө
  • u/cos Ө
  • u(1– sin Ө)
A fish looking up through the water sees the outside world contained in a circular horizon. If the refractive index of water is 4/3 and the fish is 12 cm below the surface, the radius of this circle in cm is

  • Physics-Ray Optics-85667.png
  • 2)
    Physics-Ray Optics-85668.png

  • Physics-Ray Optics-85669.png

  • Physics-Ray Optics-85670.png
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