Laws of Reflection
Take a plane mirror and focus the light coming from the Sun on a
wall. Can you see a bright spot on the wall? How does it occur? It is because
the light rays falling on the mirror are bounced onto the wall. Can you produce
the same bright spot with the help of any other object having a rough surface?
Answer: (i) All the objects cannot produce the same effect as produced
by the plane mirror.
(ii) A ray of light, falling on a body having a shiny, polished
and smooth surface alone is bounced back.
all the objects can produce the same effect as produced by the plane mirror. A
ray of light, falling on a body having a shiny, polished and smooth surface
alone is bounced back. This bouncing back of the light rays as they fall on the
smooth, shiny and polished surface is called reflection.
involves two rays: incident ray and reflected ray. The incident ray is the
light ray in a medium falling on the shiny surface of a reflecting body. After
falling on the surface, this ray returns into the same medium. This ray is
called the reflected ray. An imaginary line perpendicular to the reflecting
surface, at the point of incidence of the light ray, is called the normal.
relation between the incident ray, the reflected ray and the normal is given as
the laws of reflection. The laws of reflection are as follows:
* The incident ray, the reflected ray and the
normal at the point of incidence, all lie in the same plane.
The angle of incidence (i) and the
angle of reflection (r) are always equal.
Silver metal is the best reflector of light. That is why a thin
layer of silver is deposited on the side of materials like plane glass sheets,
to make mirrors.