NCERT Class 10 Science Chapter 10 Overview
Chapter 10 "Light Reflection And Refraction" is the first chapter of physics class 10 of NCERT book.In this chapter we have to study different phenomena's related to light such as reflection and refraction.
As you have already read about reflection in class 9, we can say that we have to study about refraction in this chapter light.
We have to study about two types of images such as real image and virtual image.
We have to study about 3 types of mirrors, plane mirror, convex mirror and concave mirror. We also have to read about lenses such as cocave lens and convex lens.
Notes of Class 10 Science Chapter 10
1. Ray of light
When a line is drawn in the direction of movement of light it is called a ray of light.2. Beam of LIght
When a number of rays are emitted by a source of light then they are known as a beam of light.- Parallel Beam = A group of rays of light parallel to each other is known as a parallel beam of light.
- Divergent Beam = A group of light rays spreading out from a source of light is called a divergent beam.
- Convergent Beam = A group of light rays meeting at a point is called a convergent beam.
3. Reflection of Light
The phenomena of sending the light back in the same medium when light strikes an object.4. Laws of Reflection
- The ray of incidence, the ray reflection, and the normal at the point of incidence, all lie in the same plane.
- The angle made by the incident ray and the angle made by the reflected ray with normal is always equal to each other. <i = <r
5. Image
When light rays meet or intersect or appear to intersect after reflection from a mirror or refraction from a lens, then it is an image.- Real Image = Image formed by the actual intersection of light rays after reflection. It can be obtained on the screen.
- Virtual Image = It is a kind of image formed by false intersection done by imaginary backward rays from the actual reflecting rays. It can not be obtained on the screen.
6. Plane Mirror
A plane mirror is a piece of straight glass whose one side is polished with silver paint while the was left for reflection of light.7. Spherical Mirrors
It is a part of a hollow glass sphere whose one side is polished.- Concave Mirror = It is a spherical mirror whose outer side is polished and the inner or concave side is reflecting surface.
- Convex Mirror = It is a spherical mirror whose inner is polished and the outer or concave side is reflecting surface.
8. Principal Focus
A point on the principal axis of a spherical mirror where the rays of light parallel to the principal axis meet after reflection from a mirror or refraction from the lens.9. Focal Length
The distance between the pole(P) and principal focus(F) of a spherical mirror or lens. It is denoted by a small 'f'.10. Use of concave lens
- It is used while shaving because when it is close to the face, it forms a large image.
- It is used as solar heating devices like solar cookers because it converges the sun's rays over a small area to produce high temperatures.
- It is used for security checking purposes.
11. Uses of convex Mirror
- It is used as a rearview in automobiles because it gives an erect image as well as diminished due to which it has a wider field of view.
- It is also used in street lights.
12. Mirror Formula
It is a relation between the distance of the object(u), the distance of image(v) it's the focal length(f) of a mirror.1/f + 1/u + 1/v
13. Magnification
The is defined as the ratio of height of image(h') to the height of object(h).m = h'/h
Also, m = v/u (for lens)
m = -v/u (for mirror)
14. Refraction of Light
The bending of rays of light when it passes from one medium to another.15. Laws of Refraction
- The ray of incidence, the ray reflection, and the normal at the point of incidence, all lie in the same plane.
- When a ray of light undergoes refraction than the ratio of sine<i to the sine<r(angle of refraction) is constant.
16. The refractive index
The refractive index of medium 2 with respect to medium 1 is the ratio of the speed of light in medium 1(V1) and the speed of light in medium 2(V2). This is represented by N21.N21 = V1/V2
17. Spherical Lenses
The lens is a transparent medium that is formed by joining two pieces of spherical glass.- Convex lens = It is a lens that is thicker at the center and thinner at the edges.
- Concave Lens = It is a lens that is thinner at the center and thicker at the edges.
18. Terms Related To Lens
- Optical Centre = It is the center of a lens through which light can pass without any deviation.
- Principal Axis = It is the line passing through the center of curvature and pole(center) of mirror or lens and perpendicular to the line joining edges.
- Centre of Curvature = It is the center of the sphere of which the lens or mirror is a part. It is double of focal length.
19. Lens formula
It is a relation between the distance of the object(u), the distance of image(v), and focal length(f) of a lens.1/f= 1/v - 1/u
20. Power of A Lens
The ability of a lens for converging or diverging rays of light. SI unit is dioptre. If the focal length of a lens is 1m then its power is 1 dioptre.If two lenses are placed together to form a combined lens then the power of this combined lens is equal to the sum of the power of individual lenses.
P = P1 + P2 + P4 ... Pn
Conclusion
If you love the notes, you can check the website NCERT Class 10 to get more notes for class 10.I hope you love the "Class 10 Physics Ch10 Light Reflection And Refraction Notes" by NCERT Class 10.
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