Light CBSE Notes Class 8 Chapter 16 we learn these chapter notes with help of points that makes it easy to learn and revise all the chapter and we cover all the important point of chapter Light.
Light CBSE Notes
1. Light: The natural agent that stimulates sight and makes things visible. Light is reflected from all surfaces.
2. Regular reflection takes place when light is incident on smooth, polished and regular surfaces.
3. Diffused/irregular reflection takes place from rough surfaces.
4. Reflection of Light: Bouncing back of light after striking the surface, in the same medium, is called reflection.
5. Types of Reflection:
(i) Regular Reflection: When a narrow beam of light strikes a mirror, the light will not reach your eye unless your eye is positioned at just the right place where the law of reflection is satisfied.
(ii) Diffused or Irregular Reflection: When light is incident upon a rough surface, it is reflected in many directions.
6. Two laws of reflection are
7. The angle of incidence is equal to the angle of reflection.
8. Incident ray, reflected ray and the normal drawn at the point of incidence to the reflecting surface, lie in the same plane.
9. Image formed in a plane mirror undergoes lateral inversion.
10. Two mirrors inclined to each other give multiple images.
11. Beautiful patterns are formed in a kaleidoscope because of multiple reflections.
12. Sunlight, called white light, consists of seven colours.
13. Splitting light into its constituent colours is known as dispersion.
14. Important parts of the eye are the cornea, iris, pupil, lens, retina and optic nerve.
15. A normal eye can see nearby and distant objects clearly.
16. Visually challenged persons can read and write using the Braille system.
17. Visually challenged persons to develop their other senses more sharply to improve their interaction with their environment.
18. Parts of Human Eye:
(i) Cornea: Transparent bulge on the front surface of the eyeball which protects the eye and helps in the refraction of light.
(ii) Iris: Coloured diaphragm behind the cornea which controls the amount of light entering the eye.
(iii) Pupil: Dark hole in the middle of the iris through which light enters the eye.
(iv) Eye lens: Transparent, crystalline structure behind pupil and iris.
(v) Ciliary muscles: Hole the eye lens in position and control the focal length of the eye lens.
(vi) Retina: Surface of the rear part of the eyeball where the light entering the eye is focused.
(vii) Rods and Cones: Rod cells respond to the brightness of light while cone cells respond to colours.
(viii) Blindspot: It is the least sensitive point where no roads and cones are present.
(ix) The space between the cornea and the eye lens is filled with aqueous humour.
(x) The space between the eye lens and the retina is filled with vitreous humour.