Class 12 Exam > Class 12 Questions > A far- sighted person has lost his spectacles...
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A far- sighted person has lost his spectacles. He can read a book at usual distance by looking through a pin hole because while looking through the pin hole:
- a)the focal length of the eye lens is increased
- b)it acts like concave lens
- c)the focal length of the eye lens is decreased
- d)it acts like convex lens
Correct answer is option 'C'. Can you explain this answer?
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Verified Answer
A far- sighted person has lost his spectacles. He can read a book at u...
Long-sighted people who have lost their spectacles can still read a book by looking through a small (3-4 mm) hole in a sheet of paper because by doing so due to the diffraction at the hole the focal length of the eye lens is effectively decreased. Hence the correct option is C.
Most Upvoted Answer
A far- sighted person has lost his spectacles. He can read a book at u...
Explanation:
When a person is far-sighted, it means that they have difficulty focusing on objects that are close to them. In order to read a book, they need to bring the book closer to their eyes. However, in this scenario, the person is looking through a pinhole instead of wearing their spectacles.
Pinhole as an Aid:
A pinhole can act as an aid for a far-sighted person because it limits the amount of light entering the eye. This reduces the size of the blur circle formed on the retina, allowing for a clearer image to be formed.
Role of Eye Lens:
The eye lens is responsible for focusing light onto the retina to form a clear image. In a far-sighted person, the focal length of the eye lens is longer than normal, meaning that it cannot focus light from nearby objects onto the retina.
Effect of Looking through a Pinhole:
When a far-sighted person looks through a pinhole, the pinhole acts as a small aperture that limits the amount of light entering the eye. This has two effects on the eye lens:
1. Decreased Amount of Light: The reduced amount of light entering the eye reduces the size of the blur circle formed on the retina. This allows for a clearer image to be formed, as the light rays are more focused.
2. Increased Depth of Field: The pinhole also increases the depth of field, which means that a wider range of distances can appear in focus. This helps the person to see more clearly at various distances without the need for their spectacles.
Conclusion:
When a far-sighted person looks through a pinhole, the focal length of the eye lens is decreased. This allows for a clearer image to be formed on the retina, enabling the person to read a book at the usual distance without their spectacles. The pinhole acts as an aid by limiting the amount of light entering the eye and increasing the depth of field.
When a person is far-sighted, it means that they have difficulty focusing on objects that are close to them. In order to read a book, they need to bring the book closer to their eyes. However, in this scenario, the person is looking through a pinhole instead of wearing their spectacles.
Pinhole as an Aid:
A pinhole can act as an aid for a far-sighted person because it limits the amount of light entering the eye. This reduces the size of the blur circle formed on the retina, allowing for a clearer image to be formed.
Role of Eye Lens:
The eye lens is responsible for focusing light onto the retina to form a clear image. In a far-sighted person, the focal length of the eye lens is longer than normal, meaning that it cannot focus light from nearby objects onto the retina.
Effect of Looking through a Pinhole:
When a far-sighted person looks through a pinhole, the pinhole acts as a small aperture that limits the amount of light entering the eye. This has two effects on the eye lens:
1. Decreased Amount of Light: The reduced amount of light entering the eye reduces the size of the blur circle formed on the retina. This allows for a clearer image to be formed, as the light rays are more focused.
2. Increased Depth of Field: The pinhole also increases the depth of field, which means that a wider range of distances can appear in focus. This helps the person to see more clearly at various distances without the need for their spectacles.
Conclusion:
When a far-sighted person looks through a pinhole, the focal length of the eye lens is decreased. This allows for a clearer image to be formed on the retina, enabling the person to read a book at the usual distance without their spectacles. The pinhole acts as an aid by limiting the amount of light entering the eye and increasing the depth of field.
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A far- sighted person has lost his spectacles. He can read a book at usual distance by looking through a pin hole because while looking through the pin hole:a)the focal length of the eye lens is increasedb)it acts like concave lensc)the focal length of the eye lens is decreasedd)it acts like convex lensCorrect answer is option 'C'. Can you explain this answer?
Question Description
A far- sighted person has lost his spectacles. He can read a book at usual distance by looking through a pin hole because while looking through the pin hole:a)the focal length of the eye lens is increasedb)it acts like concave lensc)the focal length of the eye lens is decreasedd)it acts like convex lensCorrect answer is option 'C'. Can you explain this answer? for Class 12 2024 is part of Class 12 preparation. The Question and answers have been prepared according to the Class 12 exam syllabus. Information about A far- sighted person has lost his spectacles. He can read a book at usual distance by looking through a pin hole because while looking through the pin hole:a)the focal length of the eye lens is increasedb)it acts like concave lensc)the focal length of the eye lens is decreasedd)it acts like convex lensCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for Class 12 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A far- sighted person has lost his spectacles. He can read a book at usual distance by looking through a pin hole because while looking through the pin hole:a)the focal length of the eye lens is increasedb)it acts like concave lensc)the focal length of the eye lens is decreasedd)it acts like convex lensCorrect answer is option 'C'. Can you explain this answer?.
A far- sighted person has lost his spectacles. He can read a book at usual distance by looking through a pin hole because while looking through the pin hole:a)the focal length of the eye lens is increasedb)it acts like concave lensc)the focal length of the eye lens is decreasedd)it acts like convex lensCorrect answer is option 'C'. Can you explain this answer? for Class 12 2024 is part of Class 12 preparation. The Question and answers have been prepared according to the Class 12 exam syllabus. Information about A far- sighted person has lost his spectacles. He can read a book at usual distance by looking through a pin hole because while looking through the pin hole:a)the focal length of the eye lens is increasedb)it acts like concave lensc)the focal length of the eye lens is decreasedd)it acts like convex lensCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for Class 12 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A far- sighted person has lost his spectacles. He can read a book at usual distance by looking through a pin hole because while looking through the pin hole:a)the focal length of the eye lens is increasedb)it acts like concave lensc)the focal length of the eye lens is decreasedd)it acts like convex lensCorrect answer is option 'C'. Can you explain this answer?.
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A far- sighted person has lost his spectacles. He can read a book at usual distance by looking through a pin hole because while looking through the pin hole:a)the focal length of the eye lens is increasedb)it acts like concave lensc)the focal length of the eye lens is decreasedd)it acts like convex lensCorrect answer is option 'C'. Can you explain this answer?, a detailed solution for A far- sighted person has lost his spectacles. He can read a book at usual distance by looking through a pin hole because while looking through the pin hole:a)the focal length of the eye lens is increasedb)it acts like concave lensc)the focal length of the eye lens is decreasedd)it acts like convex lensCorrect answer is option 'C'. Can you explain this answer? has been provided alongside types of A far- sighted person has lost his spectacles. He can read a book at usual distance by looking through a pin hole because while looking through the pin hole:a)the focal length of the eye lens is increasedb)it acts like concave lensc)the focal length of the eye lens is decreasedd)it acts like convex lensCorrect answer is option 'C'. Can you explain this answer? theory, EduRev gives you an
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