Zusammenfassung der Ressource
The human eye and the colourful world
- Parts of the eye
- Cornea(light enters the eye here)
- Aqueous humour(fluid to maintain correct pressure balance)
- Pupil(controls amount of light entering the eye)
- Iris(controls size of the pupil)
- Eye lens(finer adjustment of focal lens)
- Ciliary muscles(changes curvature of eye lens
- Expand and lens become thicker and the focal lens increases.
- When the contract the lens becomes thinner and focal les decreases
- Vitreous humour (holds spherical shape of the eye)
- Retina(light sensitive screen on which the image is formed)
- Contains rods and cones which generate electrical signals
- Optic nerve(sends electrical signals to the brain)
- Defects of the eye
- Myopia(near sightedness)
- Can see near by objects clearly.
Image is formed in front of the retina
Can be corrected using concave lens
- This defect may arise due to.
1)excessive curvature of eye lens
2)elongation of the eye ball
- Hypermetropia(far sightedness)
- Can see far off objects clearly
Image is formed behind the retina.
Can be corrected using convex lens
- The near point of the eye is farther away from normal near point(25cm)
This defect arises
1)the focal lens of the is too long
2)the eyeball has become too small
- Presbyopia(comes after ageing)
- Arises due to gradual weakening of the ciliary muscles.
When people can't see near or far objects clearly.they use bi-focal lens
Up concave
Down convex
- Dippersion of light
- Splitting of light into its component colours is called dipersion
- Different colours of light bend in diff angles.
Violet the most and red the least
A band of distinct colours we see is called a spectrum.
VIBGYOR
- Though glass prism
It splits into 7 colours.
When 2 prisms are placed white light is emerged out of the second prism(Isaac Newton)
- Any light that gives a spectrum similar to sunlight is called white light.
- Rainbow
Caused by dispersion of sunlight by tiny water droplets,present in the atmosphere.
Always formed in the direction opp to sun
Water droplets act like prisms
They refract and disperse the incedents sunlight,then reflect it internally,and finally refract it again when is comes out of the rain drop
- Atmospheric refraction
- Scattering of light