CBSE Questions for Class 10 Physics Human Eye And Colorful World Quiz 6 - MCQExams.com

The image formed by the eye lens on the retina is :
  • Real, upright and enlarged
  • Real, upright and diminished
  • Real, inverted and diminished
  • Virtual, inverted and diminished
Identify the wrong description of the given figures.
151628_cc72773f0e074ae8b7fe06cbe37ad191.png
  • 1 represents far sightedness
  • 2 is correction for short sightedness
  • 3 represent far sightedness
  • 4 represents correction for far sightedness
In the absence of atmosphere, the sky appears :
  • coloured
  • blue
  • indigo
  • black
The muscles of a normal eye are least strained when the eye is focused on an object:
  • Far away from the eye
  • Very close to the eye
  • At about $$25\ cm$$ from the eye
  • At about $$1\ m$$ from the eye
The ciliary muscles of eye control the curvature of the lens in the eye and hence and alter the effective focal length of the system. When the muscles are fully relaxed, the focal length is maximum. When the muscles are strained, the curvature of lens increases. That means, radius of curvature decreases and focal length decreases. For a clear vision, the image must be on the retina. The image distance is therefore fixed for clear vision and it equals the distance of retina from eye lens. It is about $$25\ cm$$ for a grown up person.
A person can theoretically have clear vision of an object situated at any large distance from the eye. The smallest distance at which a person can clearly see is related to minimum possible focal length. The ciliary muscles are most strained in this position. For an average grown up person, minimum distance of the object should be around $$25\ cm$$.
A person suffering from eye defects uses spectacles (eye glass). The function of lens of spectacles is to form the image of the objects within the range in which the person can see clearly. The image of the spectacle lens becomes object for the eye lens and whose image is formed on the retina.
The number of spectacle lens used for the remedy of eye defect is decided by the power of the lens required and the number of spectacle lens is equal to the numerical value of the power of lens with sign. For example, if power of the lens required is $$+3D$$ (converging lens of focal length $$100/3\ cm$$), then number of lens will be $$+3$$.
For all the calculations required, you can used the lens formula and lensmaker's formula. Assume that the eye lens is equiconvex lens. Neglect the distance between the eye lens and the spectacle lens.
A near sighted man can clearly see objects only upto a distance of $$100 cm$$ and not beyond this. The number of the spectacle lenses necessary for the remedy of this defect will be

161177_d8017d0abad84f4494d443989357c0a6.png
  • $$+1$$
  • $$-1$$
  • $$+3$$
  • $$-3$$
When the refraction takes place through a glass prism the emergent ray always bends towards the .......... of prism.
  • base
  • two
  • dispersion
  • deviation
A normal eye is not able to see objects closer than 25 cm because:
  • the focal length of the eye is 25 cm
  • the distance of the retina from the eye-lens is 25 cm
  • the eye is not able to decrease the distance between the eye-lens and retina beyond a limit
  • the eye is not able to decrease the focal length beyond a limit
Hypermetropia is
  • same thing as shortsightedness
  • same thing as long sightedness
  • sane as cataract
  • another name of night blindness
When objects at different distance are seen by the eye, which of the following remain constant?
  • The focal length of the eye-lens.
  • The object- distance from the eye-lens.
  • The radii of curvature of the eye-lens.
  • The image-distance from the eye-lens.
The distance of the eye-lens from the retina is $$x$$. For a normal eye, the maximum focal length of the eye-lens
  • $$= x$$
  • $$< x$$
  • $$> x$$
  • $$= 2x$$
The eye forms a real and inverted image of an object on the retina. If the eye lens is defective, the image of objects may be formed in front of or behind the retina. Persons in whom the image is formed in front of the retina are not able to see the distant objects clearly while if the image is formed behind the retina the person is not able to see a near object clearly. The latter kind of people is said to be longsighted.
Persons suffering from myopia cannot see clearly the
  • Distant objects
  • Near objects
  • Spherical objects
  • Neither near nor distant
A person A can clearly see object between 25 cm and 200 cm. Which of the following may represent the range of clear vision for a person B having muscles stronger than A, but all other parameter of eye identical to that of A?
  • 25 cm to 200 cm
  • 18 cm to 200 cm
  • 25 cm to 300 cm
  • 18 cm to 300 cm
What characteristic property of light is responsible for the blue colour of the sky?
  • Interference
  • Diffraction
  • Scattering
  • Dispersion
Fill in the blank spaces by choosing the correct word.
A prism is a piece of transparent material having three rectangular surfaces and .......... triangular surfaces.
  • $$three$$
  • $$two$$
  • $$four$$
  • $$one$$
During dispersion of white light by a prism, the red colour deviates :
  • most
  • least
  • normally
  • can't say
An astronaut in a spaceship the sky appears black due to:
  • Absence of atmosphere in his neighbourhood
  • Light from the sky is absorbed by the medium surrounding him
  • The fact at the height, sky radiations are only in the infra-red and the ultraviolet region
  • None of these
The power of spectacle for myopic eye is :
  • negative
  • positive
  • both positive and negative
  • none of the above
The image of an object is formed behind __________ in hypermetropia.
  • retina
  • cornea
  • rods
  • none of the above
With age 'Near point' and 'Far point' recedes due to
A. Weakening of ciliary muscles
B. decreasing ability to change the focal length
  • A is correct
  • B is correct
  • Both A and B are correct
  • Neither A nor B is correct
Match column I with column II and select the correct answer using the codes given below:
  Column I  Column II
 (A) Myopia (p) The power of accommodation of the eye decreases with ageing 
 (B) Hypermetropia (q) The focal length of the eye lens is too long 
 (C) Presbyopia (r) The focal length of the eye lens is too small
 (D) Astigmatism (s) The eyes fail to distinguish horizontal and vertical lines at the same distance 
  • (A) $$\rightarrow$$ r, (B) $$\rightarrow$$ q, (C) $$\rightarrow$$ p, (D) $$\rightarrow$$ s
  • (A) $$\rightarrow$$ p, (B) $$\rightarrow$$ r, (C) $$\rightarrow$$ s, (D) $$\rightarrow$$ q
  • (A) $$\rightarrow$$ s, (B) $$\rightarrow$$ p, (C) $$\rightarrow$$ r, (D) $$\rightarrow$$ q
  • (A) $$\rightarrow$$ q, (B) $$\rightarrow$$ r, (C) $$\rightarrow$$ p, (D) $$\rightarrow$$ s
Given is a diagram showing a defect of human eye.
Study it and answer the following questions :
Name the type of lens used to correct the defect.

209542_49524b3635df4aedb5fdcd1a8e2a80a3.png
  • $$Convex$$
  • $$Concave$$
  • $$Bifocal$$
  • All of the above can be used
Name the defect shown in figure :
209534_fd60bb89623d42beb8fedd1b184f0cca.png
  • Myopia
  • Astigmatism
  • Hypermetropia
  • Presbyopia
State true or false:
At dawn or dusk, the sun appears to be above the horizon for three or four minutes longer than it really is.
  • True
  • False
A rainbow is formed when the air is completely dry.
  • True
  • False
The speed of light will be minimum while passing through
  • Glass
  • Air
  • Water
  • Vacuum
Power of accomodation of eye implies:
  • Control intensity
  • Prevent internal reflection of light
  • Change of focal length of eye lens
  • All of the above
The nature of image formed on the retina of human eye is:
  • Virtual and erect
  • Virtual and inverted
  • Real and erect
  • Real and inverted
You can see a rainbow only when your back is towards the sun
  • True
  • False
The splitting of white light into its constituent colours by a triangular prism is called ________ .
  • Dispersion
  • Reflection
  • Refraction
  • Scattering
Blue colour of sky is due to :
  • dispersion of light
  • scattering of light
  • reflection of light
  • refraction of light
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