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All questions of The Human Eye and the Colourful World for Class 10 Exam
We use __________ lens to correct Hypermetropia- a)Biconvex
- b)Biconcave
- c)Concave
- d)Convex
Correct answer is option 'D'. Can you explain this answer?
We use __________ lens to correct Hypermetropia
a)
Biconvex
b)
Biconcave
c)
Concave
d)
Convex
|
Anjali Kapoor answered |
Concave lenses are used here. They spread the light out before it reaches the convex lens in the eye, therefore letting the image focus directly on the retina. Hyperopia is known to you probably as farsightedness.
The image formed on the retina of the human eye is- a)virtual and inverted
- b)real and inverted
- c)real and erect
- d)virtual and erect
Correct answer is option 'B'. Can you explain this answer?
The image formed on the retina of the human eye is
a)
virtual and inverted
b)
real and inverted
c)
real and erect
d)
virtual and erect
|
Pooja Shah answered |
Eye lens is convex, in nature. So, image formed by it on the retina is real and inverted.
Stars twinkle due to- a)atmospheric refraction
- b)atmospheric reflection
- c)scattering of light
- d)dispersion of light
Correct answer is option 'A'. Can you explain this answer?
Stars twinkle due to
a)
atmospheric refraction
b)
atmospheric reflection
c)
scattering of light
d)
dispersion of light
|
Deepika Shah answered |
The twinkling of a star is due to atmospheric refraction of starlight. The starlight, on entering the earth’s atmosphere, undergoes refraction continuously before it reaches the earth. The atmospheric refraction occurs in a medium of gradually changing refractive index. Since the atmosphere bends starlight towards the normal, the apparent position of the star is slightly different from its actual position.
The near point of a human eye is at a distance of- a)10 cm
- b)20 cm
- c)40 cm
- d)25 cm
Correct answer is option 'D'. Can you explain this answer?
The near point of a human eye is at a distance of
a)
10 cm
b)
20 cm
c)
40 cm
d)
25 cm
|
|
Abhi Prajapati answered |
The near point of the eye is the minimum distance of the object from the eye, which can be seen distinctly without strain. For a normal human eye, this distance is 25 cm. The far point of the eye is the maximum distance to which the eye can see the objects clearly. The far point of the normal human eye is infinity.
Ability of the eye to see objects at all distances is calleda)Binocular visionb)Myopiac)Accommodationd)HypermetropiaCorrect answer is option 'C'. Can you explain this answer?
|
Ishan Choudhury answered |
Changes in the contraction of the ciliary muscles alter the focal distance of the eye, causing nearer or future images to come into focus on the retina; this process is known as accommodation.
The danger signals installed at the top of tall buildings are red in colour. These can be easily seen from a distance because among all other colours, the red light- a)is scattered the most by smoke or fog
- b)is scattered the least by smoke or fog
- c)is absorbed the most by smoke or fog
- d)moves fastest in air
Correct answer is option 'B'. Can you explain this answer?
The danger signals installed at the top of tall buildings are red in colour. These can be easily seen from a distance because among all other colours, the red light
a)
is scattered the most by smoke or fog
b)
is scattered the least by smoke or fog
c)
is absorbed the most by smoke or fog
d)
moves fastest in air
|
Kiran Mehta answered |
Red colour has longer wavelength so least scattered by smoke or fog.
The near point of a hypermetropic person is 75 cm if the person uses eye glasses having power +1.0D, Calculate the distance of distinct vision for him?- a)+400cm
- b)-400cm
- c)-300cm
- d)+300cm
Correct answer is option 'C'. Can you explain this answer?
The near point of a hypermetropic person is 75 cm if the person uses eye glasses having power +1.0D, Calculate the distance of distinct vision for him?
a)
+400cm
b)
-400cm
c)
-300cm
d)
+300cm
|
|
Ishan Choudhury answered |
u = -75 cm
P = 1/f
f = 1 m = 100 cm
So, by lens formula ;
1/f = 1/v - 1/ u
So, 1/ v = 1/f +1/u
1/ v = 1/100 + (-1/75)
1/v = -1/300
v = -300 cm
P = 1/f
f = 1 m = 100 cm
So, by lens formula ;
1/f = 1/v - 1/ u
So, 1/ v = 1/f +1/u
1/ v = 1/100 + (-1/75)
1/v = -1/300
v = -300 cm
If an eye has near point at a distance of 0.5m, What is the power of lens required to correct it?- a)2 dioptre
- b)3 dioptre
- c)1 dioptre
- d)2.5 dioptre
Correct answer is option 'A'. Can you explain this answer?
If an eye has near point at a distance of 0.5m, What is the power of lens required to correct it?
a)
2 dioptre
b)
3 dioptre
c)
1 dioptre
d)
2.5 dioptre
|
|
Amit Kumar answered |
Since the person can't read an object at a distance of 50 cm, therefore focal length must be 0.5 m. We know that ;
P = 1/f , hence, P = 1/0.5 = 2 dioptre.
P = 1/f , hence, P = 1/0.5 = 2 dioptre.
The human eye forms the image of an object at its- a)Iris
- b)Pupil
- c)Cornea
- d)Retina
Correct answer is option 'D'. Can you explain this answer?
The human eye forms the image of an object at its
a)
Iris
b)
Pupil
c)
Cornea
d)
Retina
|
Rahul Kapoor answered |
Retina is the inner back portion of eye. Retina is composed of enormous number of light sensitive cells. Lens forms image of the visual world on retina through cornea. Light sensitive cells of retina get activated upon illumination and generate electric signals. Optic nerves send these electric signals to the brain, where these signals finally processed and interpreted to see an object as they are.
A student sitting on last bench in a classroom cannot see clearly words written on the blackboard. He is suffering from- a)long sightedness
- b)short sightedness
- c)astigmatism
- d)long sightedness as well as short sightedness
Correct answer is option 'B'. Can you explain this answer?
A student sitting on last bench in a classroom cannot see clearly words written on the blackboard. He is suffering from
a)
long sightedness
b)
short sightedness
c)
astigmatism
d)
long sightedness as well as short sightedness
|
|
Amit Sharma answered |
A student, who cannot read words written on blackboard from the last bench of his class room, is suffering from the myopia or short-sightedness defect of vision of eye.
Cataract can be cured by- a)Bi-focal Lens
- b)Convex Lens
- c)Surgery
- d)Concave lens
Correct answer is option 'C'. Can you explain this answer?
Cataract can be cured by
a)
Bi-focal Lens
b)
Convex Lens
c)
Surgery
d)
Concave lens
|
|
Rohan Kapoor answered |
Surgery to treat cataracts involves removing the clouded lens and replacing it with a synthetic new one. This procedure is safe and very effective.They're researching eye drops that may dissolve cataracts so patients don't have to go to surgery.
Ability of the eye lens to adjust its focal length is called- a)Accommodation
- b)Power
- c)Adjustment
- d)None of these
Correct answer is option 'A'. Can you explain this answer?
Ability of the eye lens to adjust its focal length is called
a)
Accommodation
b)
Power
c)
Adjustment
d)
None of these
|
Shubham Mukherjee answered |
The ability of the eye lens to adjust its focal length is called accommodation.
Which of the following phenomena of light are involved in the formation of a rainbow ?- a)Reflection, refraction and dispersion
- b)Refraction, dispersion and scattering
- c)Refraction, dispersion and internal reflection
- d)Dispersion, scattering and refraction
Correct answer is option 'C'. Can you explain this answer?
Which of the following phenomena of light are involved in the formation of a rainbow ?
a)
Reflection, refraction and dispersion
b)
Refraction, dispersion and scattering
c)
Refraction, dispersion and internal reflection
d)
Dispersion, scattering and refraction
|
|
Aditya Shah answered |
Phenomena of refraction, dispersion and internal reflection are involved in the formation of rainbow.
What Colour we obtain on mixing red green blue ?- a)White
- b)Cyan
- c)Magenta
- d)Black
Correct answer is option 'A'. Can you explain this answer?
What Colour we obtain on mixing red green blue ?
a)
White
b)
Cyan
c)
Magenta
d)
Black
|
Gaurav Kumar answered |
When red and blue light are combined, the result is magenta. When green and blue light are combined, they make cyan. Red and green light make yellow. And when all three primary colors of light are combined, we see white light.
When a beam of white light passes through a glass prism, it splits up into seven colours. This phenomenon is due to- a)refraction of light
- b)dispersion of light
- c)diffraction of light
- d)absorption of light
Correct answer is option 'B'. Can you explain this answer?
When a beam of white light passes through a glass prism, it splits up into seven colours. This phenomenon is due to
a)
refraction of light
b)
dispersion of light
c)
diffraction of light
d)
absorption of light
|
Kajal verma answered |
Splitting of white light into its constituent seven colours, while passing through a prism, is on account of dispersion of fight.
On a clear day, the sky appears to be more blue towards the zenith (overhead) than it does toward the horizon. This occurs because:- a)the atmosphere is denser higher up than it is at the earth’s surface.
- b)the temperature of the upper atmosphere is higher than it is at the earth’s surface.
- c)the sunlight travels over a longer path at the horizon, resulting in more absorption.
- d)none of the above is true.
Correct answer is option 'C'. Can you explain this answer?
On a clear day, the sky appears to be more blue towards the zenith (overhead) than it does toward the horizon. This occurs because:
a)
the atmosphere is denser higher up than it is at the earth’s surface.
b)
the temperature of the upper atmosphere is higher than it is at the earth’s surface.
c)
the sunlight travels over a longer path at the horizon, resulting in more absorption.
d)
none of the above is true.
|
|
Aditya Shah answered |
Because when the light of sun travel a long distance it meets with large amount of particles present in atmosphere. When they crush with small particles they got scattered due to which the blue color which have shorter wavelength, scatters most by which the sky seems blue.
Which of the following phenomena is not the result of total internal reflection ?- a)Twinkling of stars
- b)Mirage
- c)Looming
- d)both Looming and Twinkling of stars
Correct answer is option 'A'. Can you explain this answer?
Which of the following phenomena is not the result of total internal reflection ?
a)
Twinkling of stars
b)
Mirage
c)
Looming
d)
both Looming and Twinkling of stars
|
|
Pooja Shah answered |
Twinkling of stars is due to atmospheric refraction. Distant star acts like a point source of light. When the Starlight enters the earth's atmosphere it undergoes refraction continuously, due to changing refractive index ie. From rarer to denser medium.
A boy is wearing glasses and says that he cannot see the object kept at a distance without glasses. He is suffering from- a)Hypermetropia
- b)Cataract
- c)Presbyopia
- d)Myopia
Correct answer is option 'D'. Can you explain this answer?
A boy is wearing glasses and says that he cannot see the object kept at a distance without glasses. He is suffering from
a)
Hypermetropia
b)
Cataract
c)
Presbyopia
d)
Myopia
|
|
Raghav Bansal answered |
As Myopia is a defect of vision in which a person cannot see the distant object clearly. This can be corrected by using the concave lens of appropriate focal length
The light coming from an object enters the eye through:- a)cornea and pupil
- b)Pupil and retina
- c)iris and pupil
- d)cornea and iris
Correct answer is option 'A'. Can you explain this answer?
The light coming from an object enters the eye through:
a)
cornea and pupil
b)
Pupil and retina
c)
iris and pupil
d)
cornea and iris
|
Vikas Kumar answered |
Light rays enter the eye through the cornea, the clear front “window” of the eye. The cornea's refractive power bends the light rays in such a way that they pass freely through the pupil the opening in the center of the iris through which light enters the eye.
The colour which deviates most in the formation of spectrum of white light by a prism is- a)Green
- b)Yellow
- c)Red
- d)Violet
Correct answer is option 'D'. Can you explain this answer?
The colour which deviates most in the formation of spectrum of white light by a prism is
a)
Green
b)
Yellow
c)
Red
d)
Violet
|
|
Rahul Kapoor answered |
When white light falls on a glass prism, each colour in it is refracted by a different angle, from which red colour is least deviated and violet most.
When light rays from stars enter into earth’s atmosphere, it travels from
- a)denser to rarer medium
- b)rarer medium to vacuum
- c)rarer to denser medium
- d)denser medium to vacuum
Correct answer is option 'C'. Can you explain this answer?
When light rays from stars enter into earth’s atmosphere, it travels from
a)
denser to rarer medium
b)
rarer medium to vacuum
c)
rarer to denser medium
d)
denser medium to vacuum
|
|
Krishna Iyer answered |
Light travels from rarer to denser medium when it enters into earth's atmosphere
A person with defective eyesight is unable to see objects clearly nearer than 1.5 m. He wants to read a book placed at a distance of 30 cm from his eyes. The type of a required lens and its focal length is- a)Concave lens, f = 37.5 cm
- b)Convex lens, f = 30.5 cm
- c)Convex lens, f = 37.5 cm
- d)Concave lens, f = 30.5 cm
Correct answer is option 'C'. Can you explain this answer?
A person with defective eyesight is unable to see objects clearly nearer than 1.5 m. He wants to read a book placed at a distance of 30 cm from his eyes. The type of a required lens and its focal length is
a)
Concave lens, f = 37.5 cm
b)
Convex lens, f = 30.5 cm
c)
Convex lens, f = 37.5 cm
d)
Concave lens, f = 30.5 cm
|
|
Rahul Kapoor answered |
This person suffers from the defect of hypermetropia.
For him u = -30cm, v = -1.5 m = -150cm
Therefore, focal length of corrective lens to be used by him is
1/f = 1/v- 1/u = 1/-150 - 1/-30 = 4/150 = 37.5cm
The positive sign shows that the lens needed is a convex lens of focal length 37.5 cm.
Hence, power of lens needed
P =1/f = 100/37.5 = 2.67D
The clear sky appears blue because- a)blue light gets absorbed in the atmosphere
- b)ultraviolet radiations are absorbed in the atmosphere
- c)violet and blue lights get scattered more than lights of all other colours by the atmosphere
- d)light of all other colours is scattered more than the violet and blue colour lights by the atmosphere
Correct answer is option 'C'. Can you explain this answer?
The clear sky appears blue because
a)
blue light gets absorbed in the atmosphere
b)
ultraviolet radiations are absorbed in the atmosphere
c)
violet and blue lights get scattered more than lights of all other colours by the atmosphere
d)
light of all other colours is scattered more than the violet and blue colour lights by the atmosphere
|
|
Kuldeep Kuldeep answered |
As the Sun is made up of all the colours, Sun scatters the colour having a shorter wavelength. Rather than other colours Violet and Blue having the shorter wavelength. So the Violet and Blue colour lights get scattered more than lights of all other colours by the atmosphere. So, option c is correct friend...
The air layer of atmosphere whose temperature is less than the hot layer behave as optically
- a)denser medium
- b)rarer medium
- c)inactive medium
- d)either denser or rarer medium
Correct answer is option 'A'. Can you explain this answer?
The air layer of atmosphere whose temperature is less than the hot layer behave as optically
a)
denser medium
b)
rarer medium
c)
inactive medium
d)
either denser or rarer medium
|
|
Anita Menon answered |
The cold air layer of the atmosphere acts as a optically denser medium than hot air because the molecules are closely packed together.
Light from an object enters the eye through the pupil and travels to the back of the eye, forming an image on the retina. What is the orientation of the retinal image, as compared to that of the original object?- a)Turned to the left
- b)Upside down
- c)Same direction
- d)Turned to the right
Correct answer is option 'B'. Can you explain this answer?
Light from an object enters the eye through the pupil and travels to the back of the eye, forming an image on the retina. What is the orientation of the retinal image, as compared to that of the original object?
a)
Turned to the left
b)
Upside down
c)
Same direction
d)
Turned to the right
|
|
Ananya Das answered |
The image will be upside down. As it passes the lens, it gets inverted.
When white light enters a prism, it gets split into its constituent colours. This is due to- a)different refractive index for different wavelength of each colour
- b)each colours has same velocity in the prism
- c)prism material have high density
- d)Scattering of light
Correct answer is option 'A'. Can you explain this answer?
When white light enters a prism, it gets split into its constituent colours. This is due to
a)
different refractive index for different wavelength of each colour
b)
each colours has same velocity in the prism
c)
prism material have high density
d)
Scattering of light
|
|
Gaurav Kumar answered |
Dispersion takes place because refractive index of the material of prisra is different for different wavelength.
A person cannot see distinctly any object placed beyond 40cm from his eyes. Calculate the power of the lens which will help him to see distant objects clearly.- a)+1 Dioptre
- b)-2.5 Dioptre
- c)-1.5 Dioptre
- d)+2 Dioptre
Correct answer is option 'B'. Can you explain this answer?
A person cannot see distinctly any object placed beyond 40cm from his eyes. Calculate the power of the lens which will help him to see distant objects clearly.
a)
+1 Dioptre
b)
-2.5 Dioptre
c)
-1.5 Dioptre
d)
+2 Dioptre
|
|
Ishan Choudhury answered |
A lens which can bring an object at infinity to 40 cm is required here.
So, u = infinity, v = -40 cm
We know, 1/f = 1/ v - 1/u
1/ f = 1/-40 - 1/infinity
So, f = -40 cm = -0. 4 m
Power of lens, P = 1/ f = 1/ -0. 4 = -2. 5 D
So, u = infinity, v = -40 cm
We know, 1/f = 1/ v - 1/u
1/ f = 1/-40 - 1/infinity
So, f = -40 cm = -0. 4 m
Power of lens, P = 1/ f = 1/ -0. 4 = -2. 5 D
A prism splits a beam of white light into seven colours because different colours have different __________________ .
- a)Speed in prism
- b)phase in prism
- c)Amplitude in prism
- d)None of these
Correct answer is option 'A'. Can you explain this answer?
A prism splits a beam of white light into seven colours because different colours have different __________________ .
a)
Speed in prism
b)
phase in prism
c)
Amplitude in prism
d)
None of these
|
|
Vikram Kapoor answered |
The phenomena due to which white light splits Into seven colours on passing through a prism is called dispersion. Upon passing through a medium, each of the colors travels at different speeds and hence has different angles of refraction leading to the splitting of the light.
Match the following with correct response.
- a)1-B, 2-D, 3-A, 4-C
- b)1-C, 2-B, 3-D, 4-A
- c)1-A, 2-C, 3-B, 4-D
- d)1-D, 2-A, 3-C, 4-B
Correct answer is option 'A'. Can you explain this answer?
Match the following with correct response.
a)
1-B, 2-D, 3-A, 4-C
b)
1-C, 2-B, 3-D, 4-A
c)
1-A, 2-C, 3-B, 4-D
d)
1-D, 2-A, 3-C, 4-B
|
Skyhigh Academy answered |
The ability of eye lens to focus near and far objects is called power of accommodation.
Nearest point which the eye can see clearly is called near points.
The farthest point to which the eye see clearly is known as far point.
Least distance of distinct vision is the minimum distance at which eye can see the object clearly without strain.
Nearest point which the eye can see clearly is called near points.
The farthest point to which the eye see clearly is known as far point.
Least distance of distinct vision is the minimum distance at which eye can see the object clearly without strain.
The fluid between the retina and the lens is called- a)vitreous humour
- b)humus
- c)aqueous humour
- d)aqua
Correct answer is option 'A'. Can you explain this answer?
The fluid between the retina and the lens is called
a)
vitreous humour
b)
humus
c)
aqueous humour
d)
aqua
|
|
Anjana Khatri answered |
The fluid-filled space between the cornea and iris. The clear, watery fluid between the cornea and the front of the vitreous. The aqueous humor bathes and nourishes the lens and maintains pressure within the eye. Since the lens and cornea have no blood supply, the aqueous humor performs the blood’s job of carrying nutrients to those structures.
The phenomena of light responsible for the working of the human eye is - a)Reflection
- b)Refraction
- c)Power of accommodation
- d)Persistence of vision
Correct answer is option 'B'. Can you explain this answer?
The phenomena of light responsible for the working of the human eye is
a)
Reflection
b)
Refraction
c)
Power of accommodation
d)
Persistence of vision
|
|
Kabir Verma answered |
The correct option is Option B.
The phenomenon of light responsible for the working of the human eye is refraction.
What happens when white light is passed from air to glass prism?- a)Reflects back
- b)Bends towards normal
- c)Passes undeviated
- d)Bends away from normal
Correct answer is option 'B'. Can you explain this answer?
What happens when white light is passed from air to glass prism?
a)
Reflects back
b)
Bends towards normal
c)
Passes undeviated
d)
Bends away from normal
|
Harshu answered |
Light bends towards the normal as the light is passing from a rarer medium to denser medium.
Which is the correct condition for the total internal reflection to occur?- a)light should pass from denser to rarer medium
- b)light should pass from rarer to denser medium
- c)Critical angle should be grater than angle of incidence
- d)All of these
Correct answer is option 'A'. Can you explain this answer?
Which is the correct condition for the total internal reflection to occur?
a)
light should pass from denser to rarer medium
b)
light should pass from rarer to denser medium
c)
Critical angle should be grater than angle of incidence
d)
All of these
|
|
Kiran Mehta answered |
The light must be travelling from a more dense medium into a less dense medium the angle of incidence must be greater than the critical angle.
Why does Sun appear slightly oval shaped at morning and evening ?- a)The rays of light from upper edge of the sun have to pass maximum thickness.
- b)Due to unequal bending of light.
- c)The rays of light from the lower edges of Sun are refracted more.
- d)All the above.
Correct answer is option 'D'. Can you explain this answer?
Why does Sun appear slightly oval shaped at morning and evening ?
a)
The rays of light from upper edge of the sun have to pass maximum thickness.
b)
Due to unequal bending of light.
c)
The rays of light from the lower edges of Sun are refracted more.
d)
All the above.
|
|
Ishan Choudhury answered |
The light rays pass through greater thickness of air because of which the light rays from the lower side of the sun are retracted more than those from the upper side. Because of unequal light bending, the sun looks oval and larger.
One cannot see through fog because :- a)light suffers total internal reflection at the droplets of fog.
- b)light is scattered by the droplets of fog.
- c)the refractive index of fog is infinity.
- d)fog absorbs light.
Correct answer is option 'B'. Can you explain this answer?
One cannot see through fog because :
a)
light suffers total internal reflection at the droplets of fog.
b)
light is scattered by the droplets of fog.
c)
the refractive index of fog is infinity.
d)
fog absorbs light.
|
Shipra Rekha Acharya answered |
One cannot see through fog, because B
light is scattered by droplets.
This happens inherently because fog is composed of water or ice crystals that remain near the surface of the earth.
It can also be known as low-lying cloud which gets influenced by topography, water bodies and wind conditions of a place.
i hope it's helpful for us....
light is scattered by droplets.
This happens inherently because fog is composed of water or ice crystals that remain near the surface of the earth.
It can also be known as low-lying cloud which gets influenced by topography, water bodies and wind conditions of a place.
i hope it's helpful for us....
The combination responsible for admitting different amounts of light into eye is- a)Ciliary muscles and pupil
- b)Ciliary muscles and crystalline lens
- c)Iris and pupil
- d)Rods and cones
Correct answer is option 'C'. Can you explain this answer?
The combination responsible for admitting different amounts of light into eye is
a)
Ciliary muscles and pupil
b)
Ciliary muscles and crystalline lens
c)
Iris and pupil
d)
Rods and cones
|
|
Rahul Kapoor answered |
The pupil regulates the amount of light that enters the eye and the Iris controls the size of the pupil.
A ray of light travelling in air fall obliquely on the surface of a calm pond. It will-- a)Turn back on its original path.
- b)Deviate away from the normal.
- c)Deviate towards the normal
- d)Go into water without deviating from its path
Correct answer is option 'D'. Can you explain this answer?
A ray of light travelling in air fall obliquely on the surface of a calm pond. It will-
a)
Turn back on its original path.
b)
Deviate away from the normal.
c)
Deviate towards the normal
d)
Go into water without deviating from its path
|
|
Rohan Kapoor answered |
It because when ray travels from rarer medium to denser it bend towards normal ...and when denser to rarer it bends away from normal.
If the image was formed in front of the retina rather than behind the retina, then the person would need to correct the vision problem by using a:- a)converging lens
- b)diverging lens
- c)polar lens
- d)achromatic lens
Correct answer is option 'B'. Can you explain this answer?
If the image was formed in front of the retina rather than behind the retina, then the person would need to correct the vision problem by using a:
a)
converging lens
b)
diverging lens
c)
polar lens
d)
achromatic lens
|
|
Raghav Bansal answered |
Nearsighted individuals have image formed in front of the retina. They must correct the problem by wearing a lens which provides for some diverging of light prior to reaching the lens of the eye. This will move the image further from the lens of the eye and back towards the retina.
The cold air layers of the atmosphere behave as optically- a)Either inactive or rarer medium
- b)Denser medium
- c)Rarer medium
- d)Inactive medium
Correct answer is option 'B'. Can you explain this answer?
The cold air layers of the atmosphere behave as optically
a)
Either inactive or rarer medium
b)
Denser medium
c)
Rarer medium
d)
Inactive medium
|
Nisha Choudhury answered |
Due to this change in speed light bends and travels when passing from one medium to other medium. When the light ray passes from rarer medium to denser medium it bends towards the normal.
Example: Light ray passing from air to glass (Air rarer medium, Glass - denser medium.
Example: Light ray passing from air to glass (Air rarer medium, Glass - denser medium.
What will be the colour of sky if there is no atmosphere on the earth?- a)Dark blue
- b)Black
- c)Red
- d)White
Correct answer is option 'B'. Can you explain this answer?
What will be the colour of sky if there is no atmosphere on the earth?
a)
Dark blue
b)
Black
c)
Red
d)
White
|
Malavika Basu answered |
Raleigh Scattering of light by the atmosphere is what causes "the sky" to appear blue (and sunsets to appear red), but that "sky" is a colour of the atmosphere. If there is no atmosphere, what colour is it?
Without the atmosphere there is nothing local to act as a (secondary) source of light, so there is no light and we conventionally call objects that emit (little or) no light "black". So the non-object that is "the sky" could be called "black".
If we consider all light from "the heavens" to be the colour of "the sky" then it is clearly not "black". Even with the atmosphere and nasty light pollution from cities, the Milky Way appears rather off-white. With an even grander view of the Universe, we are told it's overall shade is Cosmic Latte, but I would take that with a pinch of salt or, perhaps, a tint of grey when it comes to human perception.
My preferred word for the apparent colour of "the sky" would be transparent rather than "black", but a pedant could argue that "transparent" is not a colour...
Which light is easily scattered ?- a)Long wavelength light
- b)Short wavelength light
- c)Sunlight
- d)Coherent light
Correct answer is option 'B'. Can you explain this answer?
Which light is easily scattered ?
a)
Long wavelength light
b)
Short wavelength light
c)
Sunlight
d)
Coherent light
|
|
Rohit Sharma answered |
The light having short wavelength can be scattered easily. For example, blue light shorter wavelength so it is scattered more easily.
The focal length of the eye lens increases when eye musclesa)are relaxed and lens becomes thickerb)contract and lens becomes thinnerc)contract and lens becomes thickerd)are relaxed and lens becomes thinnerCorrect answer is option 'd'. Can you explain this answer?
|
|
Vikas Kumar answered |
The focal length of the eye lens increases when eye muscles. When the muscles are relaxed, the lens becomes thin. Thus, its focal length increases.
The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct the problem?- a)diverging lens of power +1.25 D
- b)converging lens of power +1.25 D
- c)diverging lens of power -1.25 D
- d)converging lens of power -1.25 D
Correct answer is option 'C'. Can you explain this answer?
The far point of a myopic person is 80 cm in front of the eye. What is the nature and power of the lens required to correct the problem?
a)
diverging lens of power +1.25 D
b)
converging lens of power +1.25 D
c)
diverging lens of power -1.25 D
d)
converging lens of power -1.25 D
|
|
Anjana Khatri answered |
Far point of the defective eye, v = -80 cm
Object distance, u = -∞ (-infinity)
To find :
Nature and power of the corrective lens.
Solution :
1/v - 1/u = 1/f
1/f = 1/(-80) - 1/(-∞)
1/f = - 1/80 + 0 [Since, 1/-∞ = 0]
1/f = - 1/80
f = -80 cm
Therefore, the corrective lens should be of the focal length 80 cm.
Power, P = 1 / focal length
As focal length is in centimetres, 1 m = 100 cm.
P = 100 / -80
P = -1.25 D
Therefore, the corrective lens is diverging or concave lens of power -1.5 D.
Image is formed for the shortsighted person:- a)Eye lens
- b)Before retina
- c)At retina
- d)Behind retina
Correct answer is option 'B'. Can you explain this answer?
Image is formed for the shortsighted person:
a)
Eye lens
b)
Before retina
c)
At retina
d)
Behind retina
|
Naina Kaur answered |
Short-sightedness (myopia) usually occurs when the eyes grow slightly too long, which means they're unable to produce a clear image of objects in the distance.
As we increase the distance of an object from the eye, the image distance:- a)increases.
- b)decreases.
- c)First increases then decreases.
- d)remains same.
Correct answer is option 'D'. Can you explain this answer?
As we increase the distance of an object from the eye, the image distance:
a)
increases.
b)
decreases.
c)
First increases then decreases.
d)
remains same.
|
|
Nisha Choudhury answered |
When the object is near , the focal length of the eye lens is increased and the rays from the object are converged on the retina. In the eye, the image distance (distance between eye lens and retina) is fixed and cannot be changed. So when we increase the distance of an object, there is no change in the image distance.
When the light is very bright- a)the iris makes the pupil expand
- b)the iris makes the pupil contract
- c)ciliary muscles contract to make the eyelens thicker
- d)ciliary muscles expand to make the eyelens thinner
Correct answer is option 'B'. Can you explain this answer?
When the light is very bright
a)
the iris makes the pupil expand
b)
the iris makes the pupil contract
c)
ciliary muscles contract to make the eyelens thicker
d)
ciliary muscles expand to make the eyelens thinner
|
|
Ananya Das answered |
When the light is very bright the iris makes the pupil contract so as to control the quantity of light entering the eye.
The change in the focal length of an eye lens is caused by the action of- a)Ciliary muscles
- b)Aqueous humour
- c)Optic nerve
- d)Pupil
Correct answer is option 'A'. Can you explain this answer?
The change in the focal length of an eye lens is caused by the action of
a)
Ciliary muscles
b)
Aqueous humour
c)
Optic nerve
d)
Pupil
|
Krish Malik answered |
The ciliary muscles change the focal length of the eye lens by changing its shape.
The refractive indices of three media P, Q, R, are 1.73, 1.33 and 2.24 respectively. Arrange these media in increasing order of their optical density.- a)Q, R, P
- b)R, Q, P
- c)Q, P, R
- d)P, Q, R
Correct answer is option 'C'. Can you explain this answer?
The refractive indices of three media P, Q, R, are 1.73, 1.33 and 2.24 respectively. Arrange these media in increasing order of their optical density.
a)
Q, R, P
b)
R, Q, P
c)
Q, P, R
d)
P, Q, R
|
|
Pooja Shah answered |
C is the correct option.Refractive Index (Index of Refraction) is a value calculated from the ratio of the speed of light in a vacuum to that in a second medium of greater density. In the question the lowest refractive index is of Q (1.33), then P (1.73), and the highest is R (2.24).
When white light passes through a glass prism- a)red coloured ray undergoes maximum deviation
- b)green coloured ray undergoes minimum deviation
- c)blue coloured ray undergoes minimum deviation
- d)violet coloured ray undergoes maximum deviation
Correct answer is option 'D'. Can you explain this answer?
When white light passes through a glass prism
a)
red coloured ray undergoes maximum deviation
b)
green coloured ray undergoes minimum deviation
c)
blue coloured ray undergoes minimum deviation
d)
violet coloured ray undergoes maximum deviation
|
|
Krishna Iyer answered |
When white light passes through a glass prism, the violet coloured ray undergoes maximum deviation. The red coloured ray undergoes minimum deviation.
A person has near point of his vision shifted to 50 cm. What lens must be used to see an object placed at 25 cm from the eye? What is the power of the lens?- a)A diverging lens of focal length 50 cm and power – 2 D
- b)A converging lens of focal length 50 cm and power + 2 D
- c)A converging lens of focal lens 50 cm and power – 2 D
- d)A diverging lens of focal length 50 cm and power + 2 D
Correct answer is option 'B'. Can you explain this answer?
A person has near point of his vision shifted to 50 cm. What lens must be used to see an object placed at 25 cm from the eye? What is the power of the lens?
a)
A diverging lens of focal length 50 cm and power – 2 D
b)
A converging lens of focal length 50 cm and power + 2 D
c)
A converging lens of focal lens 50 cm and power – 2 D
d)
A diverging lens of focal length 50 cm and power + 2 D
|
Coachify answered |
When object is placed at 25 cm, then a virtual image should form at 50 cm.
So, u = -25 cm, v= -50 cm.
So, 1/f = 1/-50 - 1/-25
f = 50 cm = 0.5 m
Power, P = 1/f = 1/0.5 = +2D
Therefore , a convex lens is needed.
So, u = -25 cm, v= -50 cm.
So, 1/f = 1/-50 - 1/-25
f = 50 cm = 0.5 m
Power, P = 1/f = 1/0.5 = +2D
Therefore , a convex lens is needed.
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