Class notes SCIENCE 086

1. Introduction to Light
 Light is a form of energy which produces the sensation of vision.
 We can see objects because light from the object enters our eyes.
 Light usually travels in a straight line.
 When light strikes a surface, it can be reflected, refracted, or absorbed.



2️. Reflection of Light
 Reflection is the bouncing back of light after striking a smooth surface.
 Smooth and shiny surfaces like mirrors show good reflection.
 Reflection helps us see images in mirrors.



3️. Laws of Reflection
There are two laws of reflection:

1. The angle of incidence (i) is always equal to the angle of reflection (r).
2. The incident ray, reflected ray, and the normal at the point of incidence
all lie in the same plane.

These laws are valid for all types of reflecting surfaces.



4️. Important Terms Related to Reflection
 Incident ray: The ray of light that falls on the mirror
 Reflected ray: The ray that bounces back
 Normal: An imaginary line drawn perpendicular to the mirror
 Angle of incidence (i): Angle between incident ray and normal
 Angle of reflection (r): Angle between reflected ray and normal



5 .Types of Mirrors
Mirrors are mainly of two types:

(a) Plane Mirror

,  Flat reflecting surface
 Forms virtual, erect, and same size image
 Image distance = object distance
 Used in homes and bathrooms

(b) Spherical Mirrors
They are part of a sphere and are of two types:

🔹 Concave Mirror
 Reflecting surface curves inwards
 Also called converging mirror
 Can form real or virtual images

🔹 Convex Mirror
 Reflecting surface curves outwards
 Also called diverging mirror
 Always forms virtual, erect, and diminished image



6️. Terms Related to Spherical Mirrors
 Pole (P): Middle point of the mirror
 Centre of Curvature (C): Centre of the sphere of which mirror is a part
 Radius of Curvature (R): Distance between P and C
 Principal Axis: Straight line passing through P and C
 Principal Focus (F): Point where parallel rays meet or appear to meet
 Focal Length (f): Distance between pole and focus

👉 Relation: f=2R




7️ .Uses of Spherical Mirrors
Uses of Concave Mirror

 Shaving mirror
 Dentist mirror
 Torch and car headlights