CBSE Questions for Class 12 Medical Physics Ray Optics And Optical Instruments Quiz 10 - MCQExams.com

The focal lengths of the objective and eye lens of telescope are respectively $$200\ cm$$ and $$5\ cm$$. The maximum magnifying power of the telescope will be.
  • $$-40$$
  • $$-48$$
  • $$-60$$
  • $$-100$$
Return of light after striking a surface is called the refraction of light.
  • True
  • False
A convex lens of focal length f produces a real image 3 times as that size of the object, the distance between the object and the lens is .
  • $$-\left ( \cfrac {2f}3 \right)$$
  • $$-\left ( \cfrac {3f}4 \right)$$
  • $$-\left ( \cfrac {4f}3 \right)$$
  • $$-\left ( \cfrac {3f}2 \right)$$
The eye can be regarded as a single refracting surface. The radius of this surface is equal to that of cornea (7.8 mm). This surface separates two media of refractive indices 1 and 1.Calculate the distance from the refracting surface at which a parallel beam of light will come to focus. 
  • 2 cm
  • 1 cm
  • 3.1 cm
  • 4.0 cm

An observer looks at a distant tree
of height $$10$$ m with a
telescope of magnifying power of $$20$$. To the
observer the tree appears :






.







  • $$10$$ times taller.
  • $$10$$ times nearer
  • $$20$$ times taller.
  • $$20$$ times nearer.
Light enters at an angle of incidence in a transparent rod of refractive index n. For what value of the refractive index of the material of rod the light once entered into it will not leave it through its lateral face whatsoever be the value of angle of incidence? 
  • $$n > \surd 2$$
  • $$n = 1$$
  • $$n = 1.1$$
  • $$n = 1.3$$
Three glass prisms A, B and C of same refractive indices are placed in contact with each other as shown in fig. 13.77 with no air gap between the prisms. A monochromatic ray of light OP passes through the prism assemble and emerges as QR. The condition of minimum deviation are satisfied in the prisms:
1438982_7818bef058e644c1a7d8a75c31cb046b.png
  • A and C
  • B and C
  • A and B
  • in all prisms A,B and C
Hypermetropia is possible in.........
  • children
  • aged person's
  • high intensity fall on eye
  • low intensity fall on eye
Three glass prisms A, B and C of same refractive are placed in contact with each other as shown on Fig. 13.77 with no air gap between the prisms. A monochromatic ray of light OP passes through the prism assembly and emerges as QR. The conditions of minimum deviation are satisfied in the prisms:
1438256_424e11d7495148ee8a0787e26eea1650.PNG
  • A and C
  • B and C
  • A and B
  • in all prisms A , B and C
The focal length of objective and eye lens of a microscope are $$4\ cm$$ and $$8\ cm$$ respectively. If the least distance of distinct vision is $$24\ cm$$ and object distance is $$4.5\ cm$$ from the objective lens, then the magnifying power of the microscope will be   
  • $$18$$
  • $$32$$
  • $$64$$
  • $$20$$
The principle section of a glass prism is isosceles triangle ABC with AB=AC, the face AC is silvered. A ray of light is incident normally on the face AB and after two reflections, it emerges from the base BC perpendicular to the base. Angle of BAC of the prism is 
  • 30$$^{ \circ }$$
  • 36$$^{ \circ }$$
  • 18$$^{ \circ }$$
  • 72$$^{ \circ }$$
When a glass rod is immersed in a liquid of same refractive index, it will _____.
  • Appear bent
  • Disappear
  • Appear longer
  • Not be affected
The image of an object is formed due to the _________ of light rays by the eye lens on the retina. 
  • reflection
  • dispersion
  • scattering
  • refraction
A convex lens forms a real image of a point object placed on its principle axis.If the upper half of the lens is painted black,the image will- 
  • be shifted downwards
  • be shifted upwards
  • not be shifted
  • shift on the principal axis
In a terrestrial telescope, the telescope, the focal length of objective is 90 cm of inverting lens is 5 cm and of eye lens is 6 cm. If the final image is at 30  cm, then the magnification will be
  • 21
  • 12
  • 15
  • 18
The focal length of an objective of a telescope is 3 meter and diameter 15 cm. Assuming for a normal eye, the diameter of the pupil is 3 mm for its complete use, the focal length of eye piece must  be
  • $$6 cm$$
  • $$6.3 cm$$
  • $$20 cm$$
  • $$60 cm$$
The angle of minimum deviation measured with a prism is $$30^o$$ and the angle of prism $$60^o$$. The refractive index of prism material is -
  • $$\sqrt{2}$$
  • $$2$$
  • $$\dfrac{3}{2}$$
  • $$\dfrac{4}{3}$$
A thick plane mirror shows a number of images of the filament of an electric bulb. Of these, the brightest image is the:
1509226_8f55c0204c4d467597446c15f9ad6e5a.png
  • First
  • Second
  • Last
  • Fourth
Three right angled prisms of refractive indices $$\mu_1$$, $$\mu_2$$ and $$\mu_3$$ are joined together ao that the faces of the middle prism are each in contact with one of the outside prisms. If the ray passes through the composite block undeviated, then 
1502318_31db38ff2e7149c49b79d9097eb6eac8.png
  • $$1 + \mu _2^2 = \mu _1^2 + \mu _3^2$$
  • $${\mu_1}^2-{\mu_3}^2+{\mu_2}^3 = 1$$
  • $${\mu_1}^2-{\mu_3}^2-{\mu_2}^3 = 1$$
  • $${\mu_2}^2+{\mu_3}^3-{\mu_2}^1 = 1$$
A thin lens produce an image of the same size as the object.Then first the optical center of the lens, distance of the object is 
  • Zero
  • 4f
  • 2f
  • f/2
A coordinate axis as shown in the the figure is kept in front of a converging lens at a distance 2f from it, where f is the focal length of the lens. Which of the following shows the approximate shape of the image? Assume that X-axis is the principal axis of the lens.

1484982_75748a88895d44dca2cd9e3d696ba6b0.png
Which colour shows maximum deviation when light is dispersed through prism?
  • Violet
  • red
  • yellow
  • blue
Find the relation between critical angle "C" of a glass prism and its Angle of Prism "A", such that all the rays will reflect back while hitting second surface of prism
  • $$A<2C$$
  • $$2A < C$$
  • $$A>2C$$
  • $$2A>C$$
A ray of light is incident on the surface of transparent medium at an angle of $$45^o$$ and is refracted in the medium at an angle of $$30^o$$. What will be the velocity of light in the transparent medium ? 
  • $$1.96 \times 10^8 m/s $$
  • $$2.12 \times 10^8 m/s$$
  • $$2.65 \times 10^8 m/s $$
  • $$1.25 \times 10^8 m/s $$
If the tube length of astronomical telescope is $$96$$cm and magnifying power is $$15$$ for normal setting, then the focal length of the objective is _________cm.
  • $$100$$
  • $$90$$
  • $$105$$
  • $$92$$
In a hologram, image is stored in the form of 
  • Diffraction pattern
  • Photograph
  • Interference pattern
  • Intensity recording
A Point source of Light is placed $$4 \ m$$ below the surface of water of refractive index $$\dfrac{5}{3}$$. the minimum diameter of a disc which should be placed over the source on the surface of water to cut-off all light coming out of water is: (μ=5/3) 
  • $$2 \ m $$
  • $$ 6 \ m$$
  • $$4\ m$$
  • $$3\ m$$
In $$n$$ simillar thin prisms of same material and refractive index are arranged in series as shown :
1703562_91468e62a1ed456c9566bdc1cdaa9b18.png
  • if $$n$$ is even number, no net deviation and no net dispersion
  • if $$n$$ is odd number, no net deviation and no net dispersion
  • it depends upon angle of prism
  • no sufficient information
Four similar prism of same material having same angle of prism are arranged. Which of the following arrangements given no net angular deviation ?
The limit of resolution of microscope, if the numerical aperture of microscope is $$0.12$$, and the wavelength of light used is $$600\ nm$$, is:
  • $$0.3\mu m$$
  • $$1.2\mu m$$
  • $$2.3\mu m$$
  • $$3\mu m$$
A thin prism of angle $$7^o$$ made of glass of refractive index $$1.5$$ is combined with another prism made of glass of $$\mu =1.75$$ to produce dispersion without deviation. The angle of second prism is :
  • $$7^o$$
  • $$4.67^o$$
  • $$9^o$$
  • $$5^o$$
One can not see through fog because:
  • fog absorbed light
  • light is scattered by the droplets in fog
  • light surfers total reflection by the droplets in the fog
  • the refractive index of fog is in infinity
The rising and setting of sun appear red because of : 
  • refraction
  • reflection
  • defraction
  • scattering
A beam of white light is incident on a combinations of  thin prism with equal angles. In the out going beam the rainbow colours are observed as shown $$ \mu $$ stands for refractive index and $$ \theta $$  for angle of dispersion. Then:
1757940_f6da2b96808d4a72b0715e26a1068940.png
  • $$ \mu_1 < \mu_2 $$
  • $$ \mu_2 = \mu_1 $$
  • $$ \theta_1 > \theta_2 $$
  • $$ \mu_1 > \mu_2 $$
Consider a system of two thin lenses as shown in figure. An object of height $$ 1\, cm $$ is placed at $$ 40\,cm $$ from convex lens. Mark the correct option related to final image formed by the two-lens-system : 
1760046_3355441f898c422f95efb7f3c82dbba3.png
  • Final image is formed at $$ 32\,cm $$ on right of concave lens and is $$ \dfrac{1}{2.2} \,cm $$ in size .
  • Final image is formed at $$ 32\,cm $$ on left side of convex lens and is $$ 1\,cm $$ in size .
  • Final image is formed at $$ 14.5\,cm $$ on the left side of of concave lens and is $$ \dfrac{1}{2.2} \,cm $$ in size .
  • None of the above
The image formed by a convex mirror is only one-third of the size of the object. If the focal length of the mirror is $$12 \,cm,$$ the image formed will be
  • $$8 \,cm$$ behind the mirror
  • $$10 \,cm$$ behind the mirror
  • $$8 \,cm$$ in front of the mirror
  • $$10 \,cm$$ in front of the mirror
For a person suffering from myopia, the image of the object is formed in front of the retina. 
  • True
  • False
Abnormalities in the normal vision of the eye are called defects of vision.
  • True
  • False
Short-sightedness is caused due to elongation of the eyeball.
  • True
  • False
Write true or false for the following statements :
Presbyopia is a type of far-sightedness.
  • True
  • False
Write true or false for the following statements :
A near sighted person can see only nearer objects clearly. 
  • True
  • False

A $$10 \mathrm{mm}$$ long awl pin is placed vertically in front of a concave mirror. A $$5 \mathrm{mm}$$ long image of the awl pin is formed at $$30 \mathrm{cm}$$ in front of the mirror. The focal length of this mirror is:
  • $$-30 \mathrm{cm}$$
  • $$-20 c m$$
  • $$-40 \mathrm{cm}$$
  • $$-60 \mathrm{cm}$$
A magnifying glass is used, as the object to be viewed can be brought closer to the eye than the normal near point. This results in
  • a larger angle to be subtended by the object at the eye and hence viewed in greater detail
  • the formation of a virtual erect image
  • increase in the field of view
  • infinite magnification at the near point
When a ray of light from air enters a denser medium, it:
  • bends away from the normal
  • bends towards the normal
  • goes undeviated
  • is reflected back
A ray of light incident on a lens parallel to its principal axis, after refraction passes through or appears to come from :
  • its first focus
  • its optical centre
  • its second focus
  • the centre of curvation of its second surface
The eye defect represented by the figure is
1822778_d2d42e168e134c1e851324885baee14b.png
  • Myopia
  • Hypermetropia
  • Cataract
  • Presbyopia
A student of class $$ 10, $$ is not able to see clearly the blackboard question when seated at a distance of $$ 5\  \mathrm{m} $$ from the board, the defect he is suffering from is
  • Myopia
  • Hypermetropia
  • Presbyopia
  • Astigmatism
Long-sightedness or hypermetropia can be corrected by
  • Planar lens
  • Concave lens
  • Convex lens
  • Bifocal lens
A thin convex lens of focal length $$10\ cm$$ is placed in contact with a concave lens of same material and of same focal length. he focal length of combination will be
  • Zero
  • Infinity
  • $$10\ cm$$
  • $$20\ cm$$
The refractive indices of glass and water w.r.t air are $$\dfrac{3}{2}$$ and $$\dfrac{4}{3}$$ respectively. The refractive index of glass w.r.t water will be
  • $$\dfrac{8}{9}$$
  • $$\dfrac{9}{8}$$
  • $$\dfrac{7}{6}$$
  • None of these
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