Question

define1. center of curvature
.
2 principal focus
3 focal length
4 magnification​

Answer 1

Explanation:

principal focus

it is a point where light rays coming parallel to the principal axis actually converge or appear to converge.

focal length

distance from the pole to principal focus is called focal length

Answer 2

Explanation:

the center of a circle which passes through a curve at a given point and has the same tangant and curvature at that point.