A student has difficulty in reading the blackboard while sitting in the last row. It shows that he is unable to see distant objects clearly. He is suffering from myopia. This defect can be corrected by using a concave lens. For more answers visit to website: https://www.tiwariacademy.com/ncert-solutRead more
A student has difficulty in reading the blackboard while sitting in the last row. It shows
that he is unable to see distant objects clearly. He is suffering from myopia. This defect
can be corrected by using a concave lens.
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 humanRead more
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.
The person is able to see nearby objects clearly, but he is unable to see objects beyond 1.2 m. This happens because the image of an object beyond 1.2 m is formed in front of the retina and not at the retina, as shown in the given figure. To correct this defect of vision, he must use a concave lens.Read more
The person is able to see nearby objects clearly, but he is unable to see objects beyond
1.2 m. This happens because the image of an object beyond 1.2 m is formed in front of
the retina and not at the retina, as shown in the given figure.
To correct this defect of vision, he must use a concave lens. The concave le ns will bring
the image back to the retina as shown in the given figure.
When the ciliary muscles are relaxed, the eye lens becomes thin, the focal length increases, and the distant objects are clearly visible to the eyes. To see the nearby objects clearly, the ciliary muscles contract making the eye lens thicker. Thus, the focal length of the eye lens decreases and theRead more
When the ciliary muscles are relaxed, the eye lens becomes thin, the focal length
increases, and the distant objects are clearly visible to the eyes. To see the nearby objects
clearly, the ciliary muscles contract making the eye lens thicker. Thus, the focal length of
the eye lens decreases and the nearby objects become visible to the eyes. Hence, the
human eye lens is able to adjust its focal length to view both distant and nearby objects
on the retina. This ability is called the power of accommodation of the eyes.
The sky appears dark instead of blue to an astronaut because there is no atmosphere in the outer space that can scatter the sunlight. As the sunlight is not scattered, no scattered light reach the eyes of the astronauts and the sky appears black to them. For more answers visit to website: https://wwRead more
The sky appears dark instead of blue to an astronaut because there is no atmosphere in the outer space that can scatter the sunlight.
As the sunlight is not scattered, no scattered light reach the eyes of the astronauts and the sky appears black to them.
During sunrise, the light rays coming from the Sun have to travel a greater distance in the earth’s atmosphere before reaching our eyes. In this journey, the shorter wavelengths of lights are scattered out and only longer wavelengths are able to reach our eyes. Since blue colour has a shorter waveleRead more
During sunrise, the light rays coming from the Sun have to travel a greater distance in the earth’s atmosphere before reaching our eyes. In this journey, the shorter wavelengths of lights are scattered out and only longer wavelengths are able to reach our eyes. Since blue colour has a shorter wavelength and red colour has a longer wavelength, the red colour is able to reach our eyes after the atmospheric scattering of light. Therefore, the Sun appears reddish early in the morning.
Planets do not twinkle because they appear larger in size than the stars as they are relatively closer to earth. Planets can be considered as a collection of a large number of point-size sources of light. The different parts of these planets produce either brighter or dimmer effect in such a way thaRead more
Planets do not twinkle because they appear larger in size than the stars as they are relatively closer to earth. Planets can be considered as a collection of a large number of point-size sources of light. The different parts of these planets produce either brighter or dimmer effect in such a way that the average of brighter and dimmer effect is zero.
Hence, the twinkling effects of the planets are nullified and they do not twinkle.
Stars emit their own light and they twinkle due to the atmospheric refraction of light. Stars are very far away from the earth. Hence, they are considered as point sources of light. When the light coming from stars enters the earth’s atmosphere, it gets refracted at different levels because of the vRead more
Stars emit their own light and they twinkle due to the atmospheric refraction of light. Stars are very far away from the earth. Hence, they are considered as point sources of light. When the light coming from stars enters the earth’s atmosphere, it gets refracted at different levels because of the variation in the air density at different levels of the atmosphere. When the star light refracted by the atmosphere comes more towards us, it appears brighter than when it comes less towards us. Therefore, it appears as if the stars are twinkling at night.
Since the size of eyes cannot increase or decrease, the image distance remains constant. When we increase the distance of an object from the eye, the image distance in the eye does not change. The increase in the object distance is compensated by the change in the focal length of the eye lens. The fRead more
Since the size of eyes cannot increase or decrease, the image distance remains constant. When we increase the distance of an object from the eye, the image distance in the eye does not change. The increase in the object distance is compensated by the change in the focal length of the eye lens. The focal length of the eyes changes in such a way that the image is always formed at the retina of the eye.
The person is suffering from an eye defect called myopia. In this defect, the image is formed in front of the retina. Hence, a concave lens is used to correct this defect of vision. Object distance, u = infinity = ∞ Image distance, v = −80 cm Focal length = f According to the lens formula, 1/v – 1/uRead more
The person is suffering from an eye defect called myopia. In this defect, the image is formed in front of the retina. Hence, a concave lens is used to correct this defect of vision.
Object distance, u = infinity = ∞
Image distance, v = −80 cm Focal length = f
According to the lens formula,
1/v – 1/u = 1/f
-1/80 – 1/∞ = 1/f
1/f = -1/80
F = -80 cm = -0.8ₘ
We know,
Power, p= 1/f(in meters)
P = 1/-0.8 = – 1.25D
A concave lens of power −1.25 D is required by the person to correct his defect.
A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from? How can it be corrected?
A student has difficulty in reading the blackboard while sitting in the last row. It shows that he is unable to see distant objects clearly. He is suffering from myopia. This defect can be corrected by using a concave lens. For more answers visit to website: https://www.tiwariacademy.com/ncert-solutRead more
A student has difficulty in reading the blackboard while sitting in the last row. It shows
that he is unable to see distant objects clearly. He is suffering from myopia. This defect
can be corrected by using a concave lens.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-11/
What is the far point and near point of the human eye with normal vision?
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 humanRead more
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.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-11/
A person with a myopic eye cannot see objects beyond 1.2 m distinctly. What should be the type of the corrective lens used to restore proper vision?
The person is able to see nearby objects clearly, but he is unable to see objects beyond 1.2 m. This happens because the image of an object beyond 1.2 m is formed in front of the retina and not at the retina, as shown in the given figure. To correct this defect of vision, he must use a concave lens.Read more
The person is able to see nearby objects clearly, but he is unable to see objects beyond
1.2 m. This happens because the image of an object beyond 1.2 m is formed in front of
the retina and not at the retina, as shown in the given figure.
To correct this defect of vision, he must use a concave lens. The concave le ns will bring
the image back to the retina as shown in the given figure.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-11/
What is meant by power of accommodation of the eye?
When the ciliary muscles are relaxed, the eye lens becomes thin, the focal length increases, and the distant objects are clearly visible to the eyes. To see the nearby objects clearly, the ciliary muscles contract making the eye lens thicker. Thus, the focal length of the eye lens decreases and theRead more
When the ciliary muscles are relaxed, the eye lens becomes thin, the focal length
increases, and the distant objects are clearly visible to the eyes. To see the nearby objects
clearly, the ciliary muscles contract making the eye lens thicker. Thus, the focal length of
the eye lens decreases and the nearby objects become visible to the eyes. Hence, the
human eye lens is able to adjust its focal length to view both distant and nearby objects
on the retina. This ability is called the power of accommodation of the eyes.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-11/
Why does the sky appear dark instead of blue to an astronaut?
The sky appears dark instead of blue to an astronaut because there is no atmosphere in the outer space that can scatter the sunlight. As the sunlight is not scattered, no scattered light reach the eyes of the astronauts and the sky appears black to them. For more answers visit to website: https://wwRead more
The sky appears dark instead of blue to an astronaut because there is no atmosphere in the outer space that can scatter the sunlight.
As the sunlight is not scattered, no scattered light reach the eyes of the astronauts and the sky appears black to them.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-11/
Why does the Sun appear reddish early in the morning?
During sunrise, the light rays coming from the Sun have to travel a greater distance in the earth’s atmosphere before reaching our eyes. In this journey, the shorter wavelengths of lights are scattered out and only longer wavelengths are able to reach our eyes. Since blue colour has a shorter waveleRead more
During sunrise, the light rays coming from the Sun have to travel a greater distance in the earth’s atmosphere before reaching our eyes. In this journey, the shorter wavelengths of lights are scattered out and only longer wavelengths are able to reach our eyes. Since blue colour has a shorter wavelength and red colour has a longer wavelength, the red colour is able to reach our eyes after the atmospheric scattering of light. Therefore, the Sun appears reddish early in the morning.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-11/
Explain why the planets do not twinkle.
Planets do not twinkle because they appear larger in size than the stars as they are relatively closer to earth. Planets can be considered as a collection of a large number of point-size sources of light. The different parts of these planets produce either brighter or dimmer effect in such a way thaRead more
Planets do not twinkle because they appear larger in size than the stars as they are relatively closer to earth. Planets can be considered as a collection of a large number of point-size sources of light. The different parts of these planets produce either brighter or dimmer effect in such a way that the average of brighter and dimmer effect is zero.
Hence, the twinkling effects of the planets are nullified and they do not twinkle.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-11/
Why do stars twinkle?
Stars emit their own light and they twinkle due to the atmospheric refraction of light. Stars are very far away from the earth. Hence, they are considered as point sources of light. When the light coming from stars enters the earth’s atmosphere, it gets refracted at different levels because of the vRead more
Stars emit their own light and they twinkle due to the atmospheric refraction of light. Stars are very far away from the earth. Hence, they are considered as point sources of light. When the light coming from stars enters the earth’s atmosphere, it gets refracted at different levels because of the variation in the air density at different levels of the atmosphere. When the star light refracted by the atmosphere comes more towards us, it appears brighter than when it comes less towards us. Therefore, it appears as if the stars are twinkling at night.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-11/
What happens to the image distance in the eye when we increase the distance of an object from the eye?
Since the size of eyes cannot increase or decrease, the image distance remains constant. When we increase the distance of an object from the eye, the image distance in the eye does not change. The increase in the object distance is compensated by the change in the focal length of the eye lens. The fRead more
Since the size of eyes cannot increase or decrease, the image distance remains constant. When we increase the distance of an object from the eye, the image distance in the eye does not change. The increase in the object distance is compensated by the change in the focal length of the eye lens. The focal length of the eyes changes in such a way that the image is always formed at the retina of the eye.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-11/
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?
The person is suffering from an eye defect called myopia. In this defect, the image is formed in front of the retina. Hence, a concave lens is used to correct this defect of vision. Object distance, u = infinity = ∞ Image distance, v = −80 cm Focal length = f According to the lens formula, 1/v – 1/uRead more
The person is suffering from an eye defect called myopia. In this defect, the image is formed in front of the retina. Hence, a concave lens is used to correct this defect of vision.
Object distance, u = infinity = ∞
Image distance, v = −80 cm Focal length = f
According to the lens formula,
1/v – 1/u = 1/f
-1/80 – 1/∞ = 1/f
1/f = -1/80
F = -80 cm = -0.8ₘ
We know,
Power, p= 1/f(in meters)
P = 1/-0.8 = – 1.25D
A concave lens of power −1.25 D is required by the person to correct his defect.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-11/