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CBSE Questions for Class 10 Physics Human Eye And Colorful World Quiz 11 - MCQExams.com
CBSE
Class 10 Physics
Human Eye And Colorful World
Quiz 11
Scattering of light is seen when light passes through:
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During formation of rainbow
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Reflected by a mirror
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passed through a prism
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Canopy of dense forest
Explanation
When the sunlight enters the dense forest, the rays of light pass through these particles of colloids and get scattered. Hence
Scattering occurs when light passes through canopy of dense forests.
Due to refraction, sunrise appears ______ sun comes to horizon and sunset appears______sun leaves horizon respectively.
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before, after
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after, before
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before, before
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after, after
Explanation
Due to refraction, light bends and sunrise appears before sun comes to horizon whereas sun disappears after leaving the horizon.
State True or False :
For correction of defects in human eye, spectacles form virtual images only.
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True
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False
Explanation
For correcting myopia, concave lens is used and it forms virtual image to bring images closer from infinity to the far point.
For correcting hypermetropia, convex lens is used and it forms virtual image to bring images farther from close objects to the near point.
Blue colour of the sky is due to
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refraction of blue light by impurities
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refraction of blue light by water
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scattering of light by water
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None of the above
Explanation
Explanation:
Raleigh scattering is responsible for the sky's blue. This scattering is the scattering of electromagnetic energy (of which light is one type) by particles with generally shorter wavelengths.
$$ Scattering \ \alpha \ \dfrac {1}{ \lambda^4} $$
The wavelength of blue light is shorter than the wavelength of other light, which causes more scattering. Hence sky appears blue.
Option C is correct.
A myopic person cannot see clearly:
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Near objects
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Objects placed at the least distance of distinct vision
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Very far objects
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None of these
Explanation
A myopic person cannot see very far objects clearly as they are unable to focus the object on the retina of their eye and the image is formed in front of the retina.
What causes difference in velocity of colours while passing from one medium to another through glass prism?
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Different wavelengths
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Different amplitudes
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Different colours
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None of the above
Explanation
Different wavelengths causes difference in velocity of colours while passing from one medium to another through glass prism,because every colour has different wavelength.And refractive index depends on wavelength of light so different wavelength mean different refractive index which means different velocities.
When white light passed through glass prism, why dispersion occurs?
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Colours of white light travels at different speeds through prism
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Colours of white light travels at same speeds through prism
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Colours of white light travels at different acceleration through prism
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Colours of white light travels at same acceleration through prism
Explanation
$$Answer:-$$ A
A light ray is refracted (bent) when it passes from one medium to another at an angle and its speed changes. At the interface, it is bent in one direction if the material it enters is denser (when light slows down) and in the other direction if the material is less dense (when light speeds up). Because different wavelengths (colors) of light travel through a medium at different speeds, the amount of bending is different for different wavelengths. Violet is bent the most and red the least because violet light has a shorter wavelength, and short wavelengths travel more slowly through a medium than longer ones do. Because white light is made up of all visible wavelengths, its colors can be separated (dispersed) by this difference in behavior.
The least distance of vision of a long-sighted person is $$60 \ cm$$. By using a spectacle lens, this distance is reduced to $$12 \ cm$$. The power of the lens is:
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$$+5.0 \ D$$
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$$+\dfrac{20}{3} \ D$$
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$$-\dfrac{10}{3} \ D$$
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$$+2.0 \ D$$
Explanation
Given that the least distance of vision is $$60 \ cm$$, which is reduced using a lens to $$12 \ cm$$. This implies that the image of an object at $$12 \ cm$$ is formed at $$60 \ cm$$ from the lens.
Hence, $$v=-60 \ cm$$ , $$u=-12 \ cm$$
$$\therefore$$ by using the lens' formula $$\cfrac { 1 }{ f } =\cfrac { 1 }{ v } -\cfrac { 1 }{ u } $$
We have $$\cfrac { 1 }{ f } =\cfrac { 1 }{ -60 } -\cfrac { 1 }{ -12 } $$
$$\Rightarrow \cfrac { 1 }{ f } =\cfrac { 1 }{ 15 }{cm}^{-1} $$ or $$\cfrac { 100 }{ 15 } m^{-1}$$
So, the power of lens, $$P=\dfrac{1}{f} = \cfrac { 100 }{ 15 } =+\cfrac { 20 }{ 3 } D$$
Which surfaces are known as refracting surfaces in the glass prism?
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Rectangular surfaces
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Triangular surfaces
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Circular surfaces
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Cylindrical surfaces
Explanation
Prism is a homogeneous, transparent, refracting material (such as glass) enclosed by two inclined plane refracting surfaces at some fixed angle called refracting angle or angle of the prism.
It has two triangular bases and three rectangular lateral surfaces which are inclined to each other as shown in the given figure. It has six vertices and nine edges. Since the base of this prism is in a triangular shape, it is called a triangular prism.
In the given figure of prism:
Triangular bases are PQR and TUS.
Three rectangular lateral surfaces are PQUT, PTSR, QRSU.
Six vertices are P, Q, R, S, T, and U.
Nine edges are RS, PT, QU, UT, ST, US, QR, QP, and RP.
When the white light passes through prism, it splits into..............colours.
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5
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8
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7
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9
Explanation
When white light passes through some transparent material such as glass prism, it splits into its seven constituent colors i.e. violet, indigo, blue, green, yellow, orange, and red (VIBGYOR) This phenomenon of splitting of white light is known as dispersion of light.
What is known as dispersion of light?
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The phenomenon due to which a polychromatic light, like sunlight, splits into its component colours, when passed through a transparent medium
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The phenomenon due to which a polychromatic light, like sunlight, splits into its component colours, when passed through a opaque medium
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The phenomenon due to which a polychromatic light, like sunlight, splits into its component colours, when passed through a translucent medium
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The phenomenon due to which a polychromatic light, like sunlight, do not splits into its component colours, when passed through a transparent medium
Explanation
When white light pass through a glass prism the white light get scatter in so many colours of light according to it's frequency and the lights are (
VIBGYOR
) ,this phenomena of scattering of light is called
dispersion of light.
Intensity of light ray in a direction after scattering by small particles (smaller than wavelength):
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decreases.
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remains the same.
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increases.
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may increase or decrease depending on the medium in the corresponding direction.
Explanation
After scattering of light by small particles, it spreads in all directions. Hence, the intensity of the scattered light in a direction is smaller then the intensity of the incident light wave.
Which of the following quantities change during the process of scattering?
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Speed.
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Wavelength.
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Direction of propagation.
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None of the above.
Explanation
After scattering, light is spread in all directions and hence the direction of propagation changes. Wavelength, speed and frequency of the light remains unchanged during the process. Also, the intensity of the light ray in a direction changes.
After scattering, the light moves in:
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the same direction as the original light ray.
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opposite to the original direction of the light ray.
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all directions.
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the direction of the shortest path.
Explanation
In scattering, light is absorbed and re-emitted in all directions (as seen in the figure) without a change in the wavelength of the light ray.
A light of a given wavelength is scattered only by a particle of a size comparable to the wavelength.
The colour of the scattered light depends on the size of the scattering particles.
Very fine particles scatter mainly blue light while particles of larger size scatter light of longer wavelengths. If the size of the scattering particles is large enough, then, the scattered light may even appear white.
When is the intensity of scattered light independent of the wavelength?
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Medium of travel is not air.
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Particles involved in scattering have size smaller than the wavelength of the incident light wave.
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Particles involved in scattering have size larger than the wavelength of the incident light wave.
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Particles scattering the light wave are not neutral in charge.
Explanation
When the particles involved in scattering are of comparable or smaller size of the wavelength of light, then the intensity of scattered light is inversely proportional to the fourth power of the wavelength. This is known as the Rayleigh scattering. Hence,
in visible spectrum, they scatter violet the most and red the least.
However, when the particles are larger than the wavelength of light, then the scattering of all wavelengths occur to same extent, i.e. the intensity of scattered light is independent of the wavelength.
A normal eye is not table to see objects closer than $$25$$cm because.
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The focal length of the eye is $$25$$cm
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The eye is not able to decrease the focal length of eye lens beyond a limit
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The distance of the retina from the eye lens is $$25$$cm
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The eye is not able to decrease the distance between the eye lens and the retina beyond a limit
Explanation
Focal length of the eye lens is adjusted by changing its radius of curvature. This is performed by the ciliary muscles. Thus it can stretch or contract upto a certain limit only and hence the focal length cannot decrease beyond a limit .
Due to the different frequency of each colour, all components of white light get _____ at a different angle.
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refracted
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reflected
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dispersed
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diffused
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diffracted
Explanation
The index of refraction of a medium depends upon the frequency of the wave refracted. Since, d
ifferent colours have different frequencies and wavelengths.
Hence, the components of the white light refract at different angles depending upon their frequencies.
Which of the following observations cannot be explained by Tyndall Effect?
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Sunlight entering a smoke filled dark room from a tiny hole.
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Sunlight entering from a canopy of dense forest.
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Speed of light in vacuum is $$3 \times 10^8\ m/s$$
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Light passed through a milk solution.
Explanation
Tyndall Effect is scattering of light in a medium containing small suspended particles. It i
s observed in many natural phenomena. Some common phenomena include the sunlight entering through forest canopy, sunlight entering a dark room from a small hole and light passed through a milk solution.
Since, the Tyndall effect is observed in a medium containing fine suspended particles. It cannot explain that the speed of light in vacuum is $$3 \times 10^8\ m/s$$.
Hence, the correct option is C.
Tyndall effect is shown by:
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particles in colloidal solution.
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particles in a very fine suspension
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large particles like stones.
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both A and B
Explanation
The Tyndall Effect (Tyndall scattering),
is the scattering of light
by particles in a colloid
or the particles in a very fine suspension. It is observed in aerosol, milk, etc.
Which of the following phenomenon is involved in Tyndall effect?
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Reflection of light.
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Refraction of light.
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Scattering of light.
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Magnification of light.
Explanation
The Tyndall Effect (Tyndall scattering),
is light scattering
by particles in a colloid
or else particles in a very fine suspension. The amount of scattering is inversely proportional to the fourth power of wavelength and hence the colour of the colloidal solution is the same as the least coloured wavelength.
For the myopic eye, the far point is farther away than the normal.
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True
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False
Explanation
Myopia is also known as near-sightedness. A person with myopia can see nearby objects clearly but cannot see distant objects distinctly. A person with this defect has the far point nearer than infinity. Such a person may see clearly up to a distance of a few meters.
Purple light has a higher index of refraction than green light which has a higher index of refraction than red light.
If the black ray represents white light traveling into the left side of the pictured prisms, which prism most accurately shows the colors of light as they come out of the prism?
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Explanation
When light passes through the prism, the particles of purple colors( shorter wavelength) more strongly scattered or deviated than green light which is more strongly scattered than the red light (higher wavelength). Hence the answer is option C.
In the following ray diagram the correctly marked angles are.
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$$\angle$$ i and $$\angle$$ e
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$$\angle$$ A and $$\angle$$ D
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$$\angle$$ i, $$\angle$$ e and $$\angle$$ D
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$$\angle$$ r, $$\angle$$A and $$\angle$$ D
Explanation
$$\angle A$$ represents the angle of a prism while $$\angle D$$ represents the angle of deviation and both are correctly marked.
As angle of refraction $$(\angle r)$$ is the angle formed by the refracted ray with the normal and is also correctly marked.
But $$\angle i$$ and $$\angle e$$ are the angles made by the incident ray with the normal and emergent ray with the normal respectively and thus are incorrectly marked.
Hence option D is correct.
For the myopic eye, the far point is farther away than normal.
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True
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False
Explanation
False
Myopia is also known as short-sightedness. The far point of a normal person is typically infinity. But a person with myopia can not see the object at a far distance. So for him, the far point is less than that of the normal eye.
State whether true or false :
When light falls on a prism the result can be magnification.
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True
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False
Explanation
When light falls on the glass prism, refraction takes place. Since the wavelength of different components of light is different and the frequency is constant, each component gets deviated by a different angle due to the difference in velocity in the glass medium. The red color having the maximum wavelength deviates the least and forms the upper part of the spectrum whereas violet having the least wavelength deviates the most.
State whether true or false :
Rainbow is produced by the dispersion of sunlight by tiny raindrops in the air.
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True
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False
Explanation
In a rainbow, raindrops in the air act as tiny prisms. When sunlight enters a raindrop, it gets dispersed (splitting into seven components) then suffers total internal reflection, and then comes out of the raindrop undergoing refraction.
The inability among the elderly to see nearby objects clearly because of the weaking of the ciliary muscles is called
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far-sightedness
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near-sightedness
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presbyopia
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astigmatism
Explanation
Presbyopia
This is caused by loss of elasticity of the lens of the eye, occurring typically in middle and old age.The ciliary muscles become weak and can not adjust shape of lens any more to change focal length of eye lens so the person can not see nearby objects clearly.
State whether true or false :
Myopia is caused due to the high converging power of the eye lens.
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True
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False
Explanation
Myopia is defined as: The Short sightedness which is the defect in an eye due to which the eye can clearly see only the closer objects. The objects at a larger distances will not be clear.This defect arises due to the increase in power of the eye lens.
Hence true.
State whether true or false.
When light passes through a prism the colour that suffers minimum deviation is violet.
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True
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False
Explanation
False
When light falls on the glass prism, refraction takes place. Since the wavelength of different components of light is different, each component gets deviated by a different angle due to the difference in velocity in the glass medium. The red color having the maximum wavelength deviates the least and forms the upper part of the spectrum whereas violet having the least wavelength deviates the most.
If the image of distant objects is formed in front of the retina, the defect of vision may be
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myopia
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hypermetropia
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cataract
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astigmatism
Explanation
In nearsightedness, also called myopia, the image of a distant object is formed in front of the retina and not at the retina. This defect arises because the power of the eye is too large due to the decrease in focal length of the crystalline lens.
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