A horizontal line that passes through the lens is called ____?

A horizontal line that passes through the lens is called ____?

ایک افقی لکیر جو عینک سے گزرتی ہے ____ کہلاتی ہے؟
Explanation
  • The principal axis is a horizontal line that passes through the centre of the lens, perpendicular to its surface.
  • It is the central axis around which the lens is symmetrical.