This presentation covers Spherical mirrors, Types of spherical mirrors, Principal focus and focal length And Sign conventions of spherical mirrors

1. LEARNING OBJECTIVES---VIDEO 2
•SPHERICAL MIRRORS
•TYPES OF SPHERICAL MIRRORS
•IMPORTANT TERMS
•PRINCIPAL FOCUS AND FOCAL LENGTH
•SIGN CONVENTIONS OF SPHERICAL
MIRRORS

2. SPHERICAL MIRRORS
• The reflecting surface of a spherical mirror is curved inwards or outwards.
• A spherical mirror is that mirror whose reflecting surface is a part of a
hollow sphere of glass.
• One side of the mirror is well polished and reflecting and other side of the
mirror is opaque.

3. TYPES OF SPHERICAL MIRRORS
• Spherical mirrors are of two types:
• 1.CONCAVE MIRROR: is that mirror in which reflecting surface is
towards the centre of the sphere of which the mirror is a part. Reflection
occurs from the bent side and other side is non reflecting which is shown
shaded.

4. SPHERICAL MIRRORS
• 2.CONVEX MIRROR: is that spherical mirror in which reflecting surface
is away from the centre of the sphere of which the mirror is a part.
Reflection occurs at the bulging out surface and the other side is shaded
which is non reflecting.

5. SOME IMPORTANT TERMS
• 1.CENTRE OF CURVATURE: of a spherical mirror is the centre of the
hollow sphere of which the spherical mirror is a part. Denoted by C
• The reflecting surface of a concave mirror is towards C and the reflecting
surface of a convex mirror is on opposite side of C.
• 2.POLE: It is the centre of the mirror. Also called vertex. Denoted by P.

6. SOME IMPORTANT TERMS
• 3.RADIUS OF CURVATURE: It is the radius of the hollow sphere of
which the spherical mirror is a part. Denoted by R.
• 4.PRINCIPALAXIS: It is the straight line passing through the centre of
curvature C and Pole P of the spherical mirror, produced on both sides.
• 5.APERTURE: It is the diameter of the reflecting surface of the mirror

7. PRINCIPAL FOCUS AND FOCAL LENGTH OF CONCAVE MIRROR
• PRINCIPAL FOCUS: It is a point on
the principal axis of the mirror, at
which rays of light incident on the
mirror in a direction parallel to the
principal axis, actually meet after
reflection from the mirror.
• Denoted by the letter F.
• FOCAL LENGTH: It is the distance
of principal focus F of the mirror
from the pole P of the mirror. Denoted
by ‘f’
• Concave mirror converges the parallel
beam of light falling on it ,so called as
a converging mirror.

8. PRINCIPAL FOCUS AND FOCAL LENGTH OF A CONVEX MIRROR
• PRINCIPAL FOCUS: It is a point on the
principal axis of the mirror, from which ,
rays of light incident on the mirror in a
direction parallel to the principal axis ,
appear to diverge, after reflection from the
mirror.
• Denoted by F.
• FOCAL LENGTH: It is the distance of the
principal focus F of the mirror from the pole
P of the mirror.
• It is represented by the letter ‘f’.
• Convex mirror diverges the parallel beam of
light falling on it, therefore it is called a
diverging mirror.
• NOTE: Focal length (f) of a spherical mirror
is half the radius of curvature(R) of the
mirror i.e. f=R/2

9. SIGN CONVENTIONS FOR SPHERICAL MIRRORS
• 1.The principal axis of the mirror is taken along X-axis of the coordinate
system and pole P of the mirror is taken as the origin.
• 2.The object is taken on the left side of the mirror i.e. light is incident on
the mirror from the left hand side.

10. SIGN CONVENTIONS FOR SPHERICAL MIRRORS
• 3.All the distances parallel to the principal axis of the spherical mirror are
measured from the pole of the mirror.
• 4.The distances measured in the direction of incident light are taken as
positive.
• 5.The distances measured in a direction opposite to the direction of incident
light are taken as negative.
• 6.The heights measured upwards and perpendicular to the principal axis of
the mirror are taken as positive.
• 7.The heights measured downwards and perpendicular to the principal axis
of the mirror are taken as negative.

11. SUMMARY
• SPHERICAL MIRRORS
• TYPES OF SPHERICAL MIRRORS
• IMPORTANT TERMS
• PRINCIPAL FOCUS AND FOCAL LENGTH
• SIGN CONVENTIONS OF SPHERICAL MIRRORS