The document discusses the anatomy and functioning of the eye, explaining how light is processed into images by the brain, including concepts like the blind spot. It also covers optical principles such as light dispersion, rainbow formation, and atmospheric refraction, explaining phenomena like twinkling stars and double rainbows. Overall, it emphasizes the interplay between light and perception through various optical instruments and natural occurrences.

1. Light

2. External parts of Eye

3. Internal parts of Eye

5. Eye Working

6. Eye Blind Spot
When light lands on your retina, it sends electrical bursts through your optic nerve to your brain.
Your brain turns the signals into a picture. The spot where your optic nerve connects to your
retina has no light-sensitive cells, so you can't see anything there. That's your blind spot.

7. Focusing objects at different positions

9. Cameras and lenses

10. Cameras and lenses

11. Optical instruments
Single lens
Multiple lenses

12. Why we see colour

13. DISPERSION OF LIGHT

14. When an inverted prism is kept a little distance away from the prism causing
dispersion or basically in the path of splitted beam, the spectrum recombines
to form white light.
Recombination of white light

15. Why we see a rainbow
A rainbow is a natural spectrum appearing in the sky after rain shower. It is caused by
dispersion of sunlight by tiny water droplets, present in the atmosphere. The water
droplet act like small prism. They refract and disperse the incident sunlight, then reflect it
internally and finally refract it again.
Due to dispersion of light and internal reflection different colours appears.

16. Why we see a double rainbow

17. Why we see a double rainbow

18. Atmospheric refraction :-

19. The twinkling of stars is due to the atmospheric refraction of star light and
due to the changing in the position of the stars and the movement of the
layers of the atmosphere. So the light from the stars is sometimes brighter
and sometimes fainter and it appears to twinkle.
Planets are closer to the earth than stars. The light from stars are
considered as point source of light and the light from planets are considered
as extended source of light. So the light from the planets nullify the twinkling
effect.
Twinkling of stars :-