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CBSE Questions for Class 10 Physics Human Eye And Colorful World Quiz 3 - MCQExams.com
CBSE
Class 10 Physics
Human Eye And Colorful World
Quiz 3
The impression of an image does not vanish immediately from the retina. It persists there for
about $$1/16^{th}$$ of a second.
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True
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False
Explanation
The impression of an image does not vanish immediately from the retina. It persists there for about 1/16th of a second. Its called persistence of vision.
The least distance of distinct vision for a normal person is about :
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1 m
1
m
1m
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$$0.5\;m$$
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$$0.25\;m$$
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$$25 \ m$$
Explanation
The minimum distance, at which objects can be seen most distinctly without strain, is called the least distance of distinct vision. It is also called the near point of the eye. For a young adult with normal vision, the near point is about 25 cm
which is equivalent to 0.25 m, thus option $$C$$ is correct.
The near point of a myopic eye is $$15$$ cm. What should be the power of the lens which will enable the eye to read a book placed at $$30$$ cm?
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$$3.33$$ dioptre
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$$-3.33$$ dioptre
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$$2.22$$ dioptre
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$$-2.22$$ dioptre
Explanation
Given:- v=-15cm
u=-30cm
from lens formula.
$$\cfrac { 1 }{ v } -\cfrac { 1 }{ u } =\cfrac { 1 }{ f } =\cfrac { 1 }{ -15 } +\cfrac { 1 }{ 30 } =\cfrac { 1 }{ f } $$
$$\cfrac { 1 }{ f } =\cfrac { -1 }{ 30 } { cm }^{ -1 }$$ .
So power of lens = $$\cfrac { 1 }{ { f }} =\cfrac { -1 }{ 0.3 } { m }^{ -1 }$$
P= -3.33D.
Why are school buses painted with yellow colour?
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Because yellow colour make the vehicles look good
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Our eyes are mostly sensitive to yellow colour
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Our eyes are least sensitive to yellow colour
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All are true
Explanation
School buses are painted with yellow colour because our eyes are mostly sensitive to yellow colour (and are least sensitive for violet and red colours). So, school buses can be easily spotted by other drivers around and a safe distance can be maintained to ensure safety of children.
It is very difficult to see through fog because
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of scattering of light
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of total internal reflection
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fog is good absorber of light
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refractive index offog is very large
Explanation
Scattering is a phenomenon of forcing the deviation of light ray from its regular trajectory.Hence visibility in fog is less.
One cannot see through fog because .......... .
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Fog absorbs light
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Refractive index of fog is unity
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Light suffers total internal reflection at the droplets in fog
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Light is scattered by the droplets in fog
Explanation
Answer is D.
We cannot see through fog because of scattering.
Atoms and molecules in the air, including anything carried in the air like dust or smoke, will scatter light. Water droplets, as they are present in fog, also scatter light. The light falling on an object and reflected to a viewer can be scattered to heck and back before it gets to the place where it can be 'seen' by an observer. So the observer just sees a 'whiteout' instead of being able to make out anything beyond a few meters or so.
Motion pictures or cinematography make use of :
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Least distance of distinct vision
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Persistence of vision
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Power of accommodation
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None of these
Explanation
Persistence of vision is the phenomenon when eye and brain hold on to a series of images to form a single complete picture.
It refers to the optical illusion whereby multiple discrete images blend into a single image in the human mind and believed to be the explanation for motion perception in cinema and animated films.
Hence Motion pictures or cinematography make use of persistence of vision.
Fine beam of light entering through a small hole in a dark room illuminates the particles in its path. Identify the effect associated with this process.
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Schottky effect
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Rutherford effect
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Tyndall effect
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Photoelectric effect
Explanation
When fine beam of light entering through a small hole in a dark room, it illuminates the particle in its paths because of collision of particles of air and dust. This happens because of the Tyndall effect.
Lens of an eye is a transparent spherical structure which:
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reflects light
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scatters light
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refracts light
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diffracts light
Explanation
The
lens
is a transparent structure behind the iris, the coloured part of the
eye
. The
lens
bends light rays so that they form a clear image at the back of the
eye
– on the retina. As the
lens
is elastic, it can change shape, getting fatter to focus close objects and thinner for distant objects.
Transparent front part of eye is:
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pupil
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cornea
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iris
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retina
Explanation
Light enters the eye through a curved front surface known as cornea. It is transparent in nature.
The part of human eye which is sensitive to red, blue and green light is:
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Retina
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Lens
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Cornea
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Iris
Explanation
The retina is the screen of an eye. Photo-receptors like rods and cones are present on the retina. So it is sensitive to different colors.
What are the changes in ciliary muscle when nearby objects and distant objects are viewed?
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When objects near the eyes are viewed,the ciliary muscles contract and while viewing distant objects ciliary muscles relax.
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When objects near the eyes are viewed,the ciliary muscles relax and while viewing distant objects ciliary muscles contract.
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Cilliary muscle is not related to the functioning of the lens and provides mechanical support only.
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Ciliary muscles contract or relax depending on the intensity of the light and not hte distance of the object.
Explanation
The change in the curvature of the eye lens can thus change its focal length. When the muscles are relaxed, the lens becomes thin. Thus, its focal length increases. This enables us to see distant objects clearly. When you are looking at objects closer to the eye, the ciliary muscles contract. This increases the curvature of the eye lens. The eye lens then becomes thicker. Consequently, the focal length of the eye lens decreases. This enables us to see nearby objects clearly.
Aqueous humour is a _________ and vitreous humour is a _________.
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Transparent jelly, viscousfluid
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Transparent jelly, watery fluid
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Viscous fluid, viscous fluid
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Viscous fluid, transparent jelly
Explanation
The space between the cornea and the eye lens is filled with a viscous liquid called aqueous humor and the space between the eye lens and retina contains a transparent jelly called vitreous humor, thus option $$D$$ is correct.
Shape of eye ball is:
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Flat
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Spherical
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Oval
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Fish shaped
Explanation
Human eyeball is spherical in shape. Its diameter is varies as $$2.1 \ cm-2.7 \ cm$$, hence option $$B$$ is correct.
Which part of eye is responsible for its characteristic colour
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Pupil
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Iris
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Cornea
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Sclera
Explanation
Iris may be pigmented and is thus responsible for the characteristic colour of the eye, hence option $$B$$ is correct.
The power of accommodation is achieved by by changing:
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curvature of eye lens
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focal length of eye lens
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both A and B
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neither A nor B
Explanation
By changing the curvature of the lens and its focal length, the image of nearby or distant objects can be made to form on the retina. This is called the power of accommodation.
Variable focal length of eye is responsible for:
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accommodation of eye
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persistence of vision
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colour blindness
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least distance of distinct vision
Explanation
Power
of accommodation of human eye is the ability of the eye to observe distinctly the objects situated at widely different distances from the eye. This is made possible by the adjustment of the focal length of the eye lens by the action of ciliary muscles holding the lens.
Image forming light sensitive screen of the eye is known as __________ and it contains __________.
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iris, blind spot
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cornea, blind spot
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retina, photoreceptors
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cornea, photoreceptors
Explanation
The lens of the eye forms a real, inverted image of the object on the inner coat of the eye. The screen of eye is called the retina. It is a delicate membrane having enormous number of light sensitive cells or photo-receptors, i.e rod and cone cells.
What is the function of aqueous humour?
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Helps in transmitting impulses to the brain
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Protect the eyeball from collapsing
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Keeps the cornea moist and give definite shape to the eyeball
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All
Explanation
Aqueous humour is present between cornea and eye lens. It keeps the cornea moist and maintains the shape of eye ball.
Which of the following statement is correct?
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Vitreous fluid helps to maintain the shape of the retina
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Crystalline eye lens helps in focusing the image
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Aqueous humour helps to maintain the pressure in the eye
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All of the above
Explanation
Vitreous humour is a clear gelatinous gel like fluid that fills the space between the lens and the retina. It helps in maintaining the shape of the retina by holding the retina in its place. The crystalline lens helps in finer adjustments of focal length required to focus objects at different distances and forms an inverted real image of the object on the retina. Aqueous humour is present between the lens and the cornea and helps in maintaining the pressure in the eye
A glass prism has how many rectangular surfaces?
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$$3$$
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$$4$$
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$$2$$
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$$1$$
Explanation
The structure of glass prism is as shown in figure. It has three rectangular surfaces - ABCF, BCDE and AFDE.
The path of a ray of light passing through a glass prism is shown below :
In this diagram the angle of prism, angle of incidence, angle of emergence and angle of deviation respectively have been represented by:
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O, Y, Z and N,
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P, Y, M and Z,
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O, X, M and Z
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P, X, Z and N
Explanation
Angle of prism $$= \angle O$$ , (angle between two refracting surfaces)
Angle of incidence $$= \angle X$$ (angle between incident ray and normal) ,
Angle of emergence $$= \angle M$$ (angle between emergent ray and normal)
Angle of deviation $$= \angle Z$$ (angle between incident ray and emergent ray)
A person cannot see objects clearly beyond 50cm. The power of lens to correct the vision is
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+5D
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-2D
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-0.5D
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+2D
Explanation
A person cannot see beyond 50 cm. Hence, he should use a concave lens of 50 cm focal length.Hence $$Power=\dfrac{-100}{50} =-2 D$$
Red and blue beams of light is incident on a prism as shown in the figure. Which of the following statements is true?
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The blue light bends more than the red light as the blue light has a longer wavelength.
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The red light bends more than the blue light as the red light has a longer wavelength.
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The blue light bends more than the red light as the blue light has a shorter wavelength.
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The red light bends more than the blue light as the red light has a shorter wavelength.
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The red and blue lights bend by the same amount as all colors of light refract equally.
Explanation
Different colours of light bend through different angles with respect to the incident ray, as they pass through a prism. The red light bends the least while the violet the most.
It is because the refractive index of glass is more for shorter wavelength than for longer wavelengths. Since b
lue light has a shorter wavelength than red light, so blue light bends more.
Option C is correct.
The human eye forms the image of an object at its :
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cornea
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iris
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pupil
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retina
Explanation
$$\textbf{Explanation}$$
$$\bullet$$The screen of the eye on which the image is formed is known as retina
.
$$\textbf{Hence option D correct}$$
Which of the following lens is used to correct myopia?
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Convex lens
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Concave lens
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Cylindrical lens
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None of these
Explanation
In Myopia, the image of a nearby object is formed ahead of the retina.
By placing a concave (negative powered) lens in front of a myopic eye, the image is moved farther to the lens and is focussed correctly on the retina.
Due to which phenomena the combination of red, green and blue forms the same white colour
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Due to persistence of vision
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Due to reflection
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Due to refraction
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Due to deviation
Explanation
The above question can be understood by Newton Disc experiment.
The Newton disc, also known as the Disappearing Colour Disc, is a well-known physics experiment with a rotating disc with segments in different colors (usually Newton's primary colors: red, orange, yellow, green, blue, indigo, and violet or VIBGYOR) appearing as white (or off-white or gray) when it spins very fast.
The reason of white color appearance on spinning is persistence of vision.
Persistence of vision traditionally refers to the optical illusion that occurs when visual perception of an object does not cease for some time after the rays of light proceeding from it have ceased to enter the eye.
Due to this when a new color reaches our eyes previous color is still felt by our eyes and previous colors and succeeding colors combined together to form white color hence the rotating disc appears white because due to persistence of vision all colors are felt by our eyes at same time and combined together they appear white .
The change in focal length of an eye lens is caused by the action of
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pupil
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retina
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ciliary muscles
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iris
Explanation
The answer is C.
The ciliary muscle is a circular muscle that relaxes or tightens the zonules to enable the lens to change shape for focusing. The zonules are fibers that hold the lens suspended in position and enable it to change shape during accommodation. It increases or decreases the focal length of the eye lens.
A parallel beam of light falling on the eye gets focused on the retina because of refraction at
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The cornea
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The crystalline lens
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The vitreous humor
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Various surfaces in the eye
Explanation
Most of the refraction for the light rays entering the eye occurs at the outer surface of the cornea.
The power of accommodation for the normal eye is
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4 D
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40 D
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44 D
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400 D
Explanation
Normal vision length = $$25\ cm$$
Thus, the focal length is $$f = 0.25 m$$
Power $$P=\dfrac{1}{f}=\dfrac{1}{.25}=4D$$
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