LENS

1. THE DISTANCE YOU HAVE MEASURED FROM (IMAGE FORMED) A CERTAIN POINT TO THE LENS

1.1. FOCAL LENGTH

2. CONVEX LENS

3. CENTER OF CURVATURE OF A LENS

3.1. THE LINE JOINING THE CENTER OF CURVATURE OF LENS IS PRINCIPAL AXIS

4. OPTIC CENTER OF A LENS

4.1. THE MIDPOINT OF THE LENS IS THE OPTIC CENTER

5. CONCAVE LENS

6. PRINCIPAL FOCUS

6.1. THE POINT WHERE THE RAYS MEET

7. MAGNIFICATION

7.1. THE RATIO BETWEEN HEIGHT OF THE IMAGE TO THE HEIGHT OF THE OBJECT