Reflection of Light Part-1

REFLECTIONS OF LIGHT

When a ray of light approaches a smooth polished surface and the light ray bounces back, it is called the reflection of light.

 Laws –

i) The angle of incidence is equal to the angle of reflection, 

ii) The incident ray, the normal to the mirror at the point of incidence and the reflected ray, all lie in the same plane.

Some terms related to Reflections of Light:

  • Incident Ray: The ray of light that strikes the surface is called the incident ray.
  • Point of Incidence: The point of incidence is that point at which light is incident on the reflecting surface. i.e., the point at which the incident ray falls on the reflecting surface.
  • Normal: The perpendicular drawn to the reflecting surface at the point of incidence is called normal.
  • Reflected Ray: The ray of light which is turned back after reflection into the same medium in which the incident light is travelling is called the reflected ray.
  • Angle of Incidence: The angle of incidence is the angle between a ray incident on a surface and the line perpendicular to the surface at the point of incidence, called the normal
  • Angle of Reflection :The angle formed by a reflected ray and a perpendicular to the surface at the point of reflection

Mirror

A highly polished smooth surface reflecting surface is called mirror.

Types of Mirror:

1. Plane Mirror:- A highly polished plane surface is called a plane mirror.

2. Spherical Mirror:- A highly polished curved surface whose reflecting surface is a cut part of hollows at glass sphere is called a spherical mirror. Spherical mirrors are of two types:

  • Concave Mirror

        A spherical mirror, whose bent in surface is reflecting surface, is called a concave mirror.

  • Convex Mirror

       A spherical mirror, whose bulging out surface is reflecting surface, is called a convex mirror.

Some terms Related to Spherical Mirror:

  • Centre of Curvature: It is the centre of the sphere of which the mirror or lens is a part.
  • Radius of Curvature (R): The radius of the hollow sphere of which the mirror is a part, is called radius of curvature.
  • Pole: The central point of the spherical mirror is called its pole (P).
  • Focus: When a parallel beam of light rays is incident on a spherical mirror, then after reflection it meets or appears to meet at a point on principal axis, which is called focus of the spherical mirror.
  • Focal Length: The distance between the pole and focus is called focal length (f).

Image formation by Spherical Mirror:

1. Concave Mirror:

2. Convex Mirror: