Podcast
Questions and Answers
The human eye is like a ______.
The human eye is like a ______.
camera
The human eye uses ______ and enables us to see objects around us.
The human eye uses ______ and enables us to see objects around us.
light
Light enters the eye through a thin membrane called the ______.
Light enters the eye through a thin membrane called the ______.
cornea
The ______ system forms an image on a light-sensitive screen called the retina.
The ______ system forms an image on a light-sensitive screen called the retina.
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The human eye is one of the most valuable and sensitive ______ organs.
The human eye is one of the most valuable and sensitive ______ organs.
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The ______ is a delicate membrane having enormous number of light-sensitive cells.
The ______ is a delicate membrane having enormous number of light-sensitive cells.
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The ______ muscles contract when you are looking at objects closer to the eye.
The ______ muscles contract when you are looking at objects closer to the eye.
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The ability of the eye lens to adjust its focal length is called ______.
The ability of the eye lens to adjust its focal length is called ______.
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The minimum distance, at which objects can be seen most distinctly without strain, is called the ______ distance of distinct vision.
The minimum distance, at which objects can be seen most distinctly without strain, is called the ______ distance of distinct vision.
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The ______ point of the eye is the farthest point upto which the eye can see objects clearly.
The ______ point of the eye is the farthest point upto which the eye can see objects clearly.
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Study Notes
The Human Eye
- The human eye is a sense organ that enables us to see the world around us, with the ability to identify colors.
- It is like a camera, with a lens system that forms an image on a light-sensitive screen called the retina.
Structure of the Eye
- The eye has a transparent bulge on the front surface called the cornea, where light enters the eye.
- The eyeball is approximately spherical in shape with a diameter of about 2.3 cm.
- The iris is a dark muscular diaphragm that controls the size of the pupil, regulating the amount of light entering the eye.
- The crystalline lens provides finer adjustment of focal length to focus objects at different distances on the retina.
Power of Accommodation
- The eye lens is composed of a fibrous, jelly-like material that can change its curvature to modify its focal length.
- The ciliary muscles can modify the curvature of the eye lens to focus on objects at different distances.
- The ability of the eye lens to adjust its focal length is called accommodation.
- The focal length of the eye lens cannot be decreased below a certain minimum limit.
Least Distance of Distinct Vision
- The minimum distance at which objects can be seen most distinctly without strain is called the least distance of distinct vision or near point of the eye.
- For a young adult with normal vision, the near point is about 25 cm.
Far Point of the Eye
- The farthest point up to which the eye can see objects clearly is called the far point of the eye.
- For a normal eye, the far point is infinity.
Vision Defects
- Sometimes, the crystalline lens of people at old age becomes milky and cloudy, leading to defects in vision.
- Lenses used in spectacles can correct defects of vision.
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Description
Learn about the structure and function of the lens in the human eye and how spectacles correct vision defects. Understand the principles of refraction and image formation by lenses. Take this quiz to test your knowledge!
