Curved / Spherical Mirrors

Images in Curved Mirrors Concave mirrors are shaped like part of the inside of a sphere, with the centre further from the object than the edges. Convex mirrors are shaped like part of the outside of a sphere, with the centre closer to the object than the edges.

Convex

Concave

The Centre of Curvature ‘C’ is the centre of the sphere of which the curved mirror forms a part. The Pole ‘P’ is the midpoint of the mirror. The Principal Axis is the straight line passing through the pole and the centre of curvature of a spherical mirror. The Normal at any point of a curved mirror is the straight line joining that point with the centre of curvature C of the mirror.

A tangent is a line that touches a curve at exactly one point without going through it. Centre of Circle Normal

Focus on the Concave Mirror Rays of light parallel to the principal axis of a mirror, reflect through a point (in case of a concave mirror) on the principal axis. This point is the focus or focal point ‘f’ of the mirror. A concave mirror is also known as a converging mirror The focus is in front of the mirror. The focus is real as the rays of light after reflection converge at the focus.

Focus on the Convex Mirror In a convex mirror, rays of light (parallel to the principal axis of a mirror), appear to diverge from a point on the principal axis. This point is the focus or focal point ‘f’ of the mirror. A convex mirror is also known as a diverging mirror The focus is behind the mirror The focus is virtual as the rays of light after reflection appear to come from the focus behind the mirror