10. The Human Eye and the Colourful World
The chapter explores the structure and functioning of the human eye, emphasizing its similarities with a camera in terms of image formation. It discusses the power of accommodation, common refractive defects of vision like myopia and hypermetropia, and their corrections through lenses. Additionally, the chapter covers optical phenomena in nature, such as the dispersion of light, the formation of rainbows, and atmospheric refraction that affects how we perceive light and color.
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Sections
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What we have learnt
- The ability of the eye to focus on both near and distant objects, by adjusting its focal length, is called the accommodation of the eye.
- The smallest distance, at which the eye can see objects clearly without strain, is called the near point of the eye or the least distance of distinct vision, and for a young adult with normal vision, it is about 25 cm.
- Common refractive defects of vision include myopia, hypermetropia, and presbyopia, which can be corrected with suitably powered lenses.
Key Concepts
- -- Accommodation
- The ability of the eye lens to adjust its focal length to focus on objects at varying distances.
- -- Myopia
- A refractive defect also known as near-sightedness, where distant objects appear blurred while nearby objects are seen clearly.
- -- Hypermetropia
- A refractive defect also known as far-sightedness, where nearby objects appear blurred while distant objects can be seen clearly.
- -- Dispersion
- The splitting of white light into its component colors by a prism.
- -- Tyndall Effect
- The scattering of light by colloidal particles that makes their path visible.
- -- Atmospheric Refraction
- The bending of light rays as they pass through layers of air at different temperatures, affecting how we perceive celestial bodies.
Additional Learning Materials
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