Reflection of light is the bouncing back of light rays in the same medium on striking a smooth and polished surface.
LAWS OF REFLECTION
- The angle of incidence(i) is equal to the angle of reflection (r).
- The incident ray,the reflected ray and the normal to the mirror at the point of incidence,all lie on the same plane.
Types of images
Real image: The image formed by the actual intersection of rays after reflection from the object and which can be obtained on a screen is called a real image.
Virtual image: The image formed if the rays of light after reflection from the object do not actually meet but appear to meet when produced backwards and which cannot be obtained on a screen is called a virtual image.
CHARACTERISTICS OF IMAGE FORMED BY A PLANE MIRROR
Image formed by a plane mirror is virtual and erect.
The image is of the same size as the object is infront of it.
The image is laterally inverted.
SPHERICAL MIRROR
A mirror whose reflecting surface is the part of a hollow sphere of glass.
A concave mirror is the spherical in which the reflecting surface is the concave or bent in surface.
A convex mirror is the spherical mirror in which the reflecting surface is the convex or bulging-out surface.
Centre of curvature: It is the centre of the hollow sphere of glass of which the mirror is a part.It lies in front of a concave mirror and behind a convex mirror.
Radius of curvature: It is the radius of the hollow sphere of glass of which the mirror is part.
Pole: The centre of reflecting surface of a spherical mirror.
Principal axis : It is the straight line passing through the centre of curvature and pole of a spherical mirror.
Aperture: It is the portion of a mirror from which the reflection of light actually takes place.
Principal focus: The point on the Principal axis of the mirror at which the rays of light incident on the mirror in a direction parallel to the Principal axis meet after reflection (in case of concave mirror) or appear to diverge (in case of convex mirror).
RELATION BETWEEN RADIUS OF CURVATURE AND FOCAL LENGTH
f=R/2