Spherical Mirrors

It is a part of a hollow sphere, whose one side is reflecting and other side is opaque.

The types of mirrors are:

• Concave mirror

• Convex mirror

Concave Mirror

Concave mirror whose reflecting surface is towards the centre of the sphere of which the mirror is a part.

Convex Mirror

Convex mirror is one whose reflecting surface is away from the centre of the sphere of which the mirror is a part.

Convex Mirror

In the above diagram,

• 'C' is the centre of curvature of the spherical mirror, which is a part of the whole sphere.

• 'P' is called the vertex or pole of the mirror, which is the mid point or centre of the spherical mirror.

• 'CP' is called the radius of curvature (R) M₁M₂ is called the aperture of the mirror.

• The straight line joining the pole and the centre C extended on both sides is called the principal axis of the mirror.

Definitions

Principal Focus

F is a point on the principal axis of the mirror at which, rays incident on the mirror in a direction parallel to the axis actually meet or appear to diverge after reflection from the mirror. F is a real point in case of concave mirror and F is a virtual point in case of convex mirror.

Focal Length

The distance of principal focus from the pole of the spherical mirror is called focal length (f) of the mirror.

i.e., PF = f

Radius of Curvature

The distance of C from P is called radius of curvature of the mirror.

i.e., PC = R