CBSE Questions for Class 12 Medical Physics Ray Optics And Optical Instruments Quiz 1 - MCQExams.com

Monochromatic light is refracted from air into the glass of refractive index $$ \mu $$. The ratio of the wavelength of incident and refracted waves is
  • 1:$$ \mu $$
  • 1:$$ \mu $$$$ ^{2} $$
  • $$ \mu $$ :1
  • 1:1
The refractive index of the material of a concave lens is $$\mu.$$ It is immersed in a medium of refractive index $$\mu_1$$. A parallel beam of light is incident on the lens. The path of the emergent rays when $$\mu_1>\mu$$ is :
What are the colours of the Sun observed most during sunrise/sunset and noon? 
  • white and red
  • reddish and orange
  • yellow and reddish
  • orange and blue
The magnifying power of a telescope with tube length $$60cm$$ is $$5$$. What is the focal length of its eye piece?
  • $$30cm$$
  • $$20cm$$
  • $$10cm$$
  • $$40cm$$
The aperture diameter of a telescope is $$5m$$. The separation between the moon and the earth is $$4\times 10^5$$ km. With light of wavelength of $$5500\overset{o}{A}$$, the minimum separation between objects on the surface of moon, so that they are just resolved, is close to?
  • $$60$$ m
  • $$20$$ m
  • $$600$$ m
  • $$200$$ m
A ray of light is incident on a prism $$\mathrm{A}BC$$ of refractive index $$\sqrt{3}$$ as shown in figure.
(a) Find the angle of incidence for which the deviation of light ray by the prism $$\mathrm{A}BC$$ is minimum.
(b) By what angle the second prism must be rotated, so that the final ray suffer net minimum deviation. 

42885.jpg
  • $$30^o$$, $$60^o$$
  • $$60^o$$, $$30^o$$
  • $$60^o$$, $$60^o$$
  • None of these
Monochromatic light is incident on a glass prism of angle A. If the refractive index of the material of the prism is $$\mu$$, a ray incident at an angle $$\theta$$, on the face AB would get transmitted through the face AC of the prism provided
299495_64b82ce4ea0e44c1918685789d66550b.png
  • $$\theta > sin^{-1}\left[\mu \, sin \left(A - sin^{-1}\left(\frac{1}{\mu}\right) \right)\right]$$
  • $$\theta < sin^{-1}\left[\mu \, sin \left(A - sin^{-1}\left(\frac{1}{\mu}\right) \right)\right]$$
  • $$\theta > cos^{-1}\left[\mu \, sin \left(A + sin^{-1}\left(\frac{1}{\mu}\right) \right)\right]$$
  • $$\theta < cos^{-1}\left[\mu \, sin \left(A + sin^{-1}\left(\frac{1}{\mu}\right) \right)\right]$$
A ray $$OP$$ monochromatic light is incident on the face $$AB$$ of prism $$ABCD$$ near vertex $$B$$ at an incident angle of $$60^{o}$$ (see figure). If the refractive index of the material of the prism is $$\sqrt{3}$$, which of the following is (are) correct?

32047.PNG
  • The ray gets totally internally reflected at face CD
  • The ray comes out through face AD
  • The angle between the incident ray and the emergent ray is 90$$^{o}$$
  • The angle between the incident ray and the emergent ray is 120$$^{o}$$
An astronomical refracting telescope will have large angular magnification and high resolution, when it has an objective lens of :
  • Large focal length and large diameter
  • Small focal length and large diameter
  • Small focal length and small diameter
  • Large focal length and small diameter
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Both Assertion and Reason are incorrect
A convex lens of refractive index $$\dfrac{3}{2}$$ has a power of 2.5 D in air. If it is placed in a liquid of refractive index 2, then the new power of the lens is:
  • - 1.25 D
  • - 1.5 D
  • 1.25 D
  • 1.5 D
When Astronauts fly at higher altitude, the sky appears dark because ;
  • Scattering of light does not take place.
  • Scattering of light takes place.
  • Refraction of light takes place.
  • Dispersion of light takes place.
Red light is used as danger signal because it is:
  • Accepted as symbol
  • Pleasing to the eye
  • Sensitive to the eye
  • Has high wavelength
Two light rays $$P$$ and $$Q$$ are incident an optical device $$'X'$$ which finally goes along $$'R'$$ and $$'S'$$. Identify optical device $$'X'$$.
713229_82c5c50dc1c544e1aa37a81c88d6ecfa.png
  • Concave lens
  • Concave mirror
  • Convex lens
  • Convex mirror
In an astronomical telescope the focal lengths of objective and eyepiece should respectively be :
  • large and small
  • small and large
  • equal
  • too small are too large
The image formed by the telescope in normal adjustment position is at :
  • $$D$$
  • $$2D$$
  • $$F$$
  • $$\text{Infinity}$$
A myopic person cannot see distinctly , objects that are :
  • near
  • far
  • Neither
  • horizontal and vertical signs
Myopia occurs due to:
  • Increase in the focal length of eye lens
  • Decrease in the distance between retina and lens
  • Decrease in the focal length of the eye lens
  • Increase in the distance between retina and lens
The optical instrument with zero power is :
  • microscope
  • telescope
  • eyepiece
  • all of the above
Inability of the eye to focus on both far and near objects with advancing age is:
  • Astigmatism
  • Presbyopia
  • Myopia
  • Hypermetropia
For a myopic (short-sighted) eye, rays from far distant objects are brought to focus at a point:
  • on the retina
  • behind the retina
  • in between eye lens and retina
  • at any position
Hypermetropia is a synonym for: 
  • Far-sightedness
  • Near-sightedness
  • Bad vision due to old age
  • None of these
In the case of hypermetropia:
  • the image of a near object is formed behind the retina
  • the image of a distant object is formed in front of the retina
  • a concave lens should be used for correction
  • a bifocal lens should be used for correction
A convex glass lens is immersed in water. Compared to the power in air, its power in water will :
  • increase
  • decrease
  • not change
  • decrease for red light and increase for violet light
The focal length of a lens of refractive index $$\mu $$ is $$f$$. If the lens is immersed in a liquid of refractive index $$\mu $$ then the focal length of lens is 
  • $$\dfrac{f}{2}$$
  • $$2f$$
  • $$\text{infinite}$$
  • $$\text{zero}$$
In which of the following instruments is final image erect?
  • Simple mircoscope
  • Compound mircoscope
  • Astronimical telescope
  • None of the above
Large aperture objective is used in telescope. Which of the following is not a function of the objective?
  • Increasing the brightness of image.
  • Reducing image size.
  • Increasing field of view.
  • Increasing intensity by gathering more light.
Cornea is a transparent spherical structure which :
  • Reflects light
  • Scatters light
  • Refracts light
  • None of these
First adjustment of a spectrometer is :
  • focusing the distant object
  • focusing the cross wires
  • focusing the slit
  • focusing near objects
In astronomical telescope, the final image is formed at:
  • the least distance of distinct vision
  • the focus of objective lens
  • the focus of the eye lens
  • beyond the focal length of eyepiece.
While viewing a distant object with telescope a housefly sits on objective lens. Then which of the following is the correct statement :
  • housefly will be seen enlarged in image
  • housefly will be seen reduced in image
  • intensity of image will be decreased
  • intensity of image will be increased
Name the part of the eye which gives colour to the eyes.
  • Retina
  • Iris
  • Cornea
  • Fovea
Magnification of an optical instrument is expressed in:
  • m
  • $$m^{-1}$$
  • D
  • It has no unit
When the light is very bright, then:
  • Iris makes pupil expand
  • Iris makes pupil contract
  • Iris and pupil remain as they are
  • None of these
If a ray of light goes from a rarer medium to a denser medium , will it bend towards the normal or away from it ?
  • bends away from the normal
  • bends towards the normal
  • goes undeviated
  • is reflected back
The focal length of a lens is $$-0.4\ m$$. The lens is:
  • Convex only
  • Concave only
  • It may be convex or conacve
  • None of these
A printed page is seen through a glass slab place on it. The printed words appear raised. This is due to:
  • Refraction at the upper surface of the slab
  • Refraction at the lower surface of the slab
  • Partial reflection at the upper surface of the slab
  • Partial reflection at the lower surface of the slab
The eye consists of a screen called ______ on which the light rays are focused.
  • Retina
  • Iris
  • Pupil
  • None of these
The refraction of light is commonly known as :
  • Bending
  • Scattering
  • Reflection
  • Interference
Long-sightedness : Hypermetropia 
Short-sightedness : 
  • Myopia
  • Focussing
  • Astigmatism
  • Accommodation
The instrument that is based on the principle that when an object is placed between first principal focus and the optic centre of convex lens, an upright, virtual and enlarged image on the same side of the object is formed, is:
  • Telescope
  • Projector
  • Camera
  • Simple microscope
Blue colour of  sky is due to:
  • scattering.
  • absorption.
  • reflection.
  • refraction.
Fill in the blanks:
The phenomenon of change in the _____of light when it passes from one transparent medium to another is refraction.
  • speed
  • direction
  • both A & B
  • None of the above
State whether true or false:
Blind spot is found in the eyes of a blind person only.
  • True
  • False
The phenomenon of light passing through the object is called :
  • Reflection
  • Refraction
  • Dispersion
  • Total internal reflection
In which of the following the final image is erect?
  • Simple microscope
  • Compound microscope
  • Astronomical telescope
  • none of these
For reading small letters with a lens
  • one has to keep a convex lens at a distance between F and 2F from the book.
  • one has to keep a concave lens at a distance less than the focal length from the book
  • one has to keep concave lens at a distance between F and 2F from the book
  • One has to keep a convex lens at a distance less than the an focal length from the book
  • None of these
In the white light of sun, maximum scattering by the air molecules present in the earth's atmosphere is for:
  • red colour
  • yellow colour
  • green colour
  • blue colour
The phenomenon due to which a ray of light .......... from its path while travelling from one optical medium to another optical medium is called refraction.
  • reflected
  • deviates
  • normally
  • less
Which of the following would you prefer to use while reading small letters found in a dictionary ?
  • A concave mirror
  • A concave lens
  • A convex mirror
  • A convex lens
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