Question

define principal axis in a spherical mirror​

Answer 1

HeRe Is UR AnS:

Principal Axis of a spherical mirror is the line passing through the centre of the mirror that is exactly perpendicular to the surface of the mirror. ... One of the light rays used to draw a ray diagram of image formation remains parallel to the principal axis that passes through the focus.

Answer 2

• a line passing through the center of the surface of a lens or spherical mirror and through the centers of curvature of all segments of the lens or mirrors