define
1. centre of curvature
2. radius of curvature
3. principle axis
4. principle focus
5. focal point
Answers
Centre of curvature: The reflecting surface of a spherical mirrorforms a part of a sphere. This sphere has a centre. This point is called centre of curvature
Radius of curvature: The radiusof the spherewhich the reflecting surfaceof a spherical mirror forms a part is called radius of curvature
Principal axis: A straight line passing through a pole and the centre of the curvature is called principal axis
centre of curvature:the center of the circle whose center lies on the concave side of a curve on the normal to a given point of the curve and whose radius is equal to the radius of curvature at that point.
radius of curvature:Radius of curvature (ROC) has specific meaning and sign convention in optical design. A spherical lens or mirror surface has a center of curvature located either along or decentered from the system local optical axis. ... The distance from the vertex to the center of curvature is the radius of curvature of the surface.
principal axis:each of three mutually perpendicular axes in a body about which the moment of inertia is at a maximum.
principal focus :focal point. n. 1 (Also called) principal focus, focus the point on the axis of a lens or mirror to which parallel rays of light converge or from which they appear to diverge after refraction or reflection.
focal point:Focal point. The focal point of a lens or mirror is the point in space where parallel light rays meet after passing through the lens or bouncing off the mirror. A "perfect" lens or mirror would send all light rays through one focal point, which would result in the clearest image.