JEE Questions for Physics Ray Optics Quiz 23 - MCQExams.com

When sunlight is scattered by minute particles of atmosphere, the intensity of light scattered away isproportional to
  • (wavelength of light) 4
  • (frequency of light) 4
  • (wavelength of light) –2
  • (frequency of light) 2
A thick plane mirror shows a number of images of the filament of an electric bulb. Of these, the brightest image is the
  • First
  • Second
  • Fourth
  • Last
A man is 180 cm tall and his eyes are 10 cm below the top of his head. In order to see his entire height right from toe to head, he uses a plane mirror kept at a distance of lm from him. The minimum length of theplane mirror required is
  • 180 cm
  • 90 cm
  • 85 cm
  • 170 cm
A person is in a room whose ceiling and two adjacent walls are mirrors. How many images are formed?
  • 5
  • 6
  • 7
  • 8
A convex mirror of focal length f forms an image whichis 1/n times the object. The distance of the object from the mirror is

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  • 2)
    Physics-Ray Optics-86740.png

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A diminished virtual image can be formed only in
  • Plane mirror
  • A concave mirror
  • A convex mirror
  • Concave-parabolic mirror
Image formed by a convex mirror is
  • Virtual
  • Real
  • Enlarged
  • Inverted
In a concave mirror experiment, an object is placed at a distance x1 from the focus and the image is formed at a distance x2 from the focus. The focal length of the mirror would be

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  • 2)
    Physics-Ray Optics-86745.png

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A convex mirror is used to form the image of an object. Then which of the following statements is wrong?
  • The image lies between the pole and the focus
  • The image is diminished in size
  • The image is erect
  • The image is real
A concave mirror of focal length f (in air) is immersed in water (µ = 4/3). The focal length of the mirror in water will be

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  • 2)
    Physics-Ray Optics-86750.png

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A boy stands straight infront of a mirror at a distance of 30 cm away from it. He sees his erect image whose height is 1/5th of his real height. The mirror he is using is
  • Plane mirror
  • Convex mirror
  • Concave mirror
  • Plano-convex mirror
What will be the height of image when an object of 2 mm is placed on the axis of a convex mirror at a distance 20 cm of radius of curvature 40 cm?
  • 20 mm
  • 10 mm
  • 6 mm
  • 1 mm
Which one of the following statements is true?
  • An object situated at the principle focus of a concave lens will have its image formed at infinity
  • Concave mirror can give diminished virtual image
  • Given a point source of light, a convex mirror can produce a parallel beam of light
  • The virtual image formed in a plane mirror can be photographed
Convergence of concave mirror can be decreased by dipping in
  • Water
  • Oil
  • Both
  • None of these
A virtual image larger than the object can be obtained by
  • Concave mirror
  • Convex mirror
  • Plane mirror
  • Concave lens
Radius of curvature of concave mirror is 40cm and the size of image is twice as that of object, then the object distance is
  • 60 cm
  • 20 cm
  • 40 cm
  • 30 cm
A convex mirror has a focal length f. A real object is placed at a distance f in front of it from the pole produces an image at
  • Infinity
  • f
  • f/2
  • 2f
Match List I with List II and select the correct answer using the codes given below the lists :
Physics-Ray Optics-86758.png
  • I-B, II-D, III-A, IV-E
  • I-A, II-D, III-C, IV-B
  • I-C, II-B, III-A, IV-E
  • I-B, II-E, III-D, N-C
A point object is placed at a distance of 10 cm and its real image is formed at a distance of 20 cm from a concave minor. If the object is moved by 0.1 cm towards the mirror, the image will shift by about
  • 0.4 cm away from the mirror
  • 0.4 cm towards the mirror
  • 0.8 cm away from the mirror
  • 0.8 cm towards the mirror
The focal length of a convex mirror is 20 cm its radius ofcurvature will be
  • 10 cm
  • 20 cm
  • 30 cm
  • 40 cm
A concave mirror of focal length 15 cm forms an image having twice the linear dimensions of the object. The position of the object when the image is virtual will be
  • 22.5 cm
  • 7.5 cm
  • 30 cm
  • 45 cm
A point object is placed at a distance of 30 cm from a convex mirror of focal length 30cm. The image will form at
  • Infinity
  • Focus
  • Pole
  • 15 cm behind the mirror
If the lower half of a concave mirror\'s reflecting surface is made opaque, which of the following statements describe the image of an object placed infront of the mirror?
S1 : Intensity of the image will increase.
S2 : The image will show only half of the object.
S3 : No change in the image.
S4 : Intensity of the image will be reduced to half.
  • S1 only
  • S2 only
  • S2 and S3
  • S4 only
When light travels from one medium to the other of which the refractive index is different, then which of the following will change?
  • Frequency, wavelength and velocity
  • Frequency and wavelength
  • Frequency and velocity
  • Wavelength and velocity
A light wave has a frequency of 4 × 1014 Hz and awavelength of 5 × 10–7metres in a medium. The refractive index of the medium is
  • 1.5
  • 1.33
  • 1.0
  • 0.66
How much water should be filled in a container 21 cm in height, so that it appears half filled when viewed from the top of the container (given that αµω = 4/3)
  • 8.0 cm
  • 10.5 cm
  • 12.0 cm
  • None of these
Monochromatic light is refracted from air into the glass of refractive index µ. The ratio of the wavelength of incident and refracted waves is
  • 1 : µ
  • 1 : µ2
  • µ :1
  • 1 : 1
The refractive indices of glass and water w.r.t. air are 3/2 and 4/3 respectively. The refractive index of glass w.r.t. water will be
  • 8/9
  • 9/8
  • 7/6
  • None of these
If µ0 be the relative permeability and K0 the dielectric constant of a medium, its refractive index is given by

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    Physics-Ray Optics-86771.png

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If the speed of light in vacuum is C m/sec, then the velocity of light in a medium of refractive index 1.5
  • Is 1.5 ×C
  • Is C
  • Is C / 1.5
  • Can have any velocity
A ray of light is incident on the surface of a glass plate of thickness t. If the angle of incidence θ is small, the emerging ray would be displaced side ways by an amount [take n = refractive index of glass]
  • tθn / (n + 1)
  • tθ (n – 1)/ n
  • tθn / (n – 1)
  • tθ (n + 1)/ n
Monochromatic light of wavelength 589 nm is incident from air on a water surface. The refractive index of water is 1.33. The wavelength of the refracted light is
  • 589 nm
  • 443 nm
  • 333 nm
  • 221 nm
Which of the following is not a correct statement?
  • The wavelength of red light is greater than the wavelength of green light
  • The wavelength of blue light is smaller than the wavelength of orange light
  • The frequency of green light is greater than the frequency of blue light
  • The frequency of violet light is greater than the frequency of blue light
Which of the following is a correct relation?
  • αµr = αµω × rµω
  • αµr = rµω × ωµα
  • αµr × rµα = 0
  • αµr / ωµr × αµω
The distance travelled by light in glass (refractive index =1.in a nano second will be
  • 45 cm
  • 40 cm
  • 30 cm
  • 20 cm
When light is refracted from air into glass
  • Its wavelength and frequency both increase
  • Its wavelength increases but frequency remains unchanged
  • Its wavelength decreases but frequency remains unchanged
  • Its wavelength and frequency both decrease

Physics-Ray Optics-86783.png

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  • 2)
    Physics-Ray Optics-86785.png

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Ray optics is valid, when characteristic dimensions are
  • Of the same order as the wavelength of light
  • Much smaller than the wavelength of light
  • Of the order of one millimetre
  • Much larger than the wavelength of light
Electromagnetic radiation of frequency n, wavelength λ, travelling with velocity v in air, enters a glass slab of refractive index µ. The frequency, wavelength and velocity of light in the glass slab will be respectively

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  • 2)
    Physics-Ray Optics-86790.png

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What is the time taken (in seconds) to cross a glass of thickness 4 mm and µ = 3 by light?
  • 4 × 10–11
  • 2 × 10–11
  • 16 × 10–11
  • 8 × 10–11
In refraction, light waves are bent on passing from one medium to the second medium, because, in the second medium
  • The frequency is different
  • The coefficient of elasticity is different
  • The speed is different
  • The amplitude is smaller
A microscope is focused on a mark on a piece of paper and then a slab of glass of thickness 3 cm and refractive index 1.5 is placed over the mark. How should be microscope moved to get the mark in focus again?
  • 1 cm downward
  • 2 cm upward
  • 1 cm upward
  • 4.5 cm downward
The reason of seeing the Sun a little before the sunrise is
  • Reflection of the light
  • Refraction of the light
  • Scattering of the light
  • Dispersion of the light
Velocity of light in glass whose refractive index with respect to air is 1.5 is 2 × 108 m/s and in certain liquidthe velocity of light found to be 2.5 × 108 m/s. The refractive index of the liquid with respect to air is
  • 0.64
  • 0.80
  • 1.20
  • 1.44
A fish at a depth of 12 cm in water is viewed by an observer on the bank of a lake. To what height the image of the fish is raised?
  • 9 cm
  • 12 cm
  • 3.8 cm
  • 3 cm
A thin oil layer floats on water. A ray of light making an angle of incidence of 40° shines on oil layer. The angle of refraction of light ray in water is (µoil = 1.45, µwater = 1.
  • 36.1°
  • 44.5°
  • 26.8°
  • 28.9°
An object is immersed in a fluid. In order that the object becomes invisible, it should
  • Behave as a perfect reflector
  • Absorb all light falling on it
  • Have refractive index one
  • Have refractive index exactly matching with that of the surrounding fluid
When light travels from glass to air, the incident angle is θ1 and the refracted angle is θ2. The true relation is
  • θ1 = θ2
  • θ1<θ2
  • θ1>θ2
  • Not predictable
The frequency of a light ray is 6 × 1014Hz. Its frequencywhen it propagates in a medium of refractive index 1.5, will be
  • 1.67 × 1014 Hz
  • 9.10 × 1014 Hz
  • 6 × 1014 Hz
  • 4 × 1014 Hz
A glass slab of thickness 3 cm and refractive index 3/2 is placed on ink mark on a piece of paper. For a person looking at the mark at a distance 5.0 cm above it, the distance of the mark will appear to be
  • 3.0 cm
  • 4.0 cm
  • 4.5 cm
  • 5.0 cm
0:0:1


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