Reflection of light waves -Types of curved mirrors Concave (Converging) Mirror Convex (Diverging) Mirror

1. SS3

2. REFLECTION OF
LIGHT WAVE

3. CURVED MIRRORS
 Curved mirrors are pieces of glass which is part of a
sphere, hence they are called spherical mirrors.
 TYPES OF CURVED MIRRORS
 Concave Mirror
 Convex Mirror
Painting the outside of the piece of glass with silver
gives concave mirror.
Painting the inside of the piece of glass with silver gives
convex mirror.

4. CURVED MIRRORS
Concave Mirror
Convex Mirror
Reflecting
surface
Painted
surface
Reflecting
surface Painted
surface

5. TERMS ASSOCIATED WITH
CURVED MIRRORS
 Pole P- it is the centre of the mirror.
 Centre of curvature C- it is the centre of the
sphere of which the mirror is part.
 Radius of curvature r- it is the radius of the
sphere of which the mirror is part.
 Principal axis- it is a line drawn through the
pole of the mirror and the centre of curvature

6. TERMS ASSOCIATED WITH
CURVED MIRRORS
 Principal focus F – for a concave mirror, it
is the point at which all rays parallel and
close to the principal axis converge at after
reflection. In the case of a convex mirror, it
is the point at which all rays parallel and
close to the principal axis appear to diverge
from after reflection. It is also called the
focal point.
 Focal length f- it is the distance between
the pole of the mirror and its focal point.

7. TERMS ASSOCIATED WITH
CURVED MIRRORS
NOTE:
When rays are produced behind the mirror,
they are indicated using dotted lines. This
means that they are imaginary or virtual.
Hence the focal point and focal length of a
concave mirror are real while the focal
point and focal length of a convex mirror
are virtual. A real focal length is given
a positive sign while a negative focal
length is given a negative sign.

8. TERMS ASSOCIATED WITH
CURVED MIRRORS
 Ray diagrams

 Curved mirrors form images when two rays intersect or appear to intersect.
In ray diagrams, we use the following symbols to represent the two curved
mirrors:


 There are four important rays used in ray diagrams. They include:

 A ray passing through C or appearing to pass through C:

 The ray is reflected along the same path.

 A ray parallel and close to the principal axis.

 The ray is reflected through the principal focus F for a concave mirror or
appear to come from the principal focus of the convex mirror.


9. TERMS ASSOCIATED WITH
CURVED MIRRORS
 Ray diagrams

 Curved mirrors form images when two rays intersect or appear to intersect. In ray diagrams, we use the following
symbols to represent the two curved mirrors:


 There are four important rays used in ray diagrams. They include:

 A ray passing through C or appearing to pass through C:

 The ray is reflected along the same path.

 A ray parallel and close to the principal axis.

 The ray is reflected through the principal focus F for a concave mirror or appear to come from the principal focus
of the convex mirror.

 A ray passing through the principal focus F or appearing to pass through F

 The reflected ray moves parallel to the principal axis (by the principle of reversibility of light).

 A ray incident at the pole of the mirror.

 The ray is reflected making the same angle with the principal axis as the incident ray (i.e <i=<r).

 Image formation by curved mirrors