This covers Reflection,Types of reflection,Laws of Reflection

1. LEARNING OBJECTIVES----VIDEO 1
•LIGHT
•IMPORTANT TERMS
•REFLECTION OF LIGHT
•TYPES OF REFLECTION
•LAWS OF REFLECTION
•IMAGES AND ITS TYPES
•CHARACTERISTICS OF IMAGE FORMED BY PLANE MIRROR

2. LIGHT
• LIGHT:
• Light is a form of energy which produces in us a sensation of sight.
• A small source of light casts a sharp shadow of an opaque object in its path.
• This is because light travels in a straight line(Rectilinear propagation).
• Light shows dual nature– wave as well as particle.

3. IMPORTANT TERMS
1.SOURCE—It is an object from which
light is given out.
2.MEDIUM---It is a substance through
which light propagates or tries to do so.
There are three types of media---
• a)TRANSPARENT---It is a medium
through which light propagates easily
.e.g. air, water.
• b)TRANSLUCENT---It is a medium
through which light propagates partially.
E.g. paper , window panes.
• c)OPAQUE---It is medium through
which light cannot propagate. E.g. wood
,metal.

4. IMPORTANT TERMS
• 3.RAY---A ray of light is the straight line
path along which light travels. It is
represented by an arrow head on a straight
line.
• A number of rays combined together form a
BEAM of light. A narrow beam of light is
called a PENCIL.
• A pencil of light may be of three kinds---
• i)CONVERGENT PENCIL—is that in which
rays of light go to meet at a particular point
O.
• ii)DIVERGENT PENCIL---is that in which
rays of light come out of a point source S.
• iii) PARALLEL PENCIL---is that in which
all the rays move parallel to one another.

5. REFLECTION OF LIGHT
• Reflection of light is the phenomenon of bouncing back of light in the same
medium on striking the surface of any object.
• In reflection path of light rays changes without any change in medium.

6. TYPES OF REFLECTION
• Reflection is of two types:
• 1.REGULAR REFLECTION: When the reflecting surface is smooth and
well polished, the parallel rays falling on it are reflected parallel to one
another and reflected rays goes in one particular direction. This is called
Regular reflection.
• Any smooth and well polished surface from which light suffers regular
reflection is called mirror.

7. REFLECTION OF LIGHT
• 2.IRREGULAR REFLECTION: When the reflecting surface is rough, the
parallel rays falling on it are reflected in different directions .Such a
reflection is known as irregular or diffuse reflection.

8. LAWS OF REFLECTION OF LIGHT
• FIRST LAW :The incident ray, the reflected ray and the normal, all lie in
the same plane.

9. LAWS OF REFLECTION OF LIGHT
• SECOND LAW: The angle of reflection (r) is always equal to the angle of
incidence(i).
• <i = <r
• <i = 30 then <r =30

10. LAWS OF REFLECTION
• NOTE: The laws of reflection are applicable to all types of reflecting
surfaces including spherical surfaces.
• When a ray of light is incident normally on a mirror <i =0, then according
to second law , <r =<i =0.
• It means that a ray of light incident normally on the mirror ,retraces its path
on reflection.

11. IMAGES
• An IMAGE is the point where the light rays coming from an object meet or appear to
meet after reflection.
• An image is of two types---
• i)REAL IMAGE: The image formed when the light rays actually meet after reflection
is called the Real image.
• ii)VIRTUAL IMAGE: The image formed when the light rays appear to meet after
reflection is called the Virtual image.
• A Real image can be taken on screen , but a virtual image cannot be taken on the
screen.

12. CHARACTERISTICS OF IMAGES FORMED BY PLANE MIRRORS
• The image of a real object is always virtual.
• The image cannot be taken on screen.
• The image formed in a plane mirror is always
erect.
• The size of image in a plane mirror is always
the same as the size of the object.
• The image formed in a plane mirror is as far
behind the mirror , as the object is in front of
the mirror.
• The image formed in a plane mirror is laterally
inverted i.e. left appears right and vice –versa.

13. RECAP
• LIGHT
• IMPORTANT TERMS
• REFLECTION OF LIGHT
• TYPES OF REFLECTION
• LAWS OF REFLECTION
• IMAGES AND ITS TYPES
• CHARACTERISTICS OF IMAGE FORMED BY PLANE MIRROR