Introduction
Eye structure, accommodation, vision defects (myopia, hypermetropia, presbyopia), dispersion (VIBGYOR), and atmospheric scattering.
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Vision and Light Phenomena
Eye lens adjusts focal length (accommodation). Myopia: image before retina, concave lens. Hypermetropia: image behind retina, convex lens. Presbyopia: bifocal lens. Dispersion: white light through prism->VIBGYOR. Blue sky: Rayleigh scattering. Red sunset: blue scattered away over long path.
Key Points
- •Myopia: concave lens (minus power)
- •Hypermetropia: convex lens (plus power)
- •Near point=25cm; Far point=infinity
- •VIBGYOR: violet bends most, red least
- •Blue sky: shorter wavelengths scatter more
Quick Summary
- ✓Myopia: concave; Hypermetropia: convex
- ✓Dispersion: VIBGYOR
- ✓Blue sky: Rayleigh scattering; Red sunset: long path
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Key Formulas
P=1/f dioptre
Near point=25cm
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