suite

01.curriculum/01.physics-chemistry-biology/02.Niv2/04.optics/04.use-of-basic-optical-elements/01.plane-refracting-surface/02.plane-refracting-surface-overview/cheatsheet.en.md

@@ -177,15 +177,15 @@ $`\Longrightarrow\overline{SF'}=\dfrac{n_{eme}\cdot\overline{SC}}{n_{eme}-n_{inc
 $`\Longrightarrow\overline{SF}=-\dfrac{n_{inc}\cdot\overline{SC}}{n_{eme}-n_{inc}}`$   (equ.5)
 
 !!!! *ADVISE* :<br>
-!!!! Memory does not replace understanding. Do not memorise (equ.4) and (equ.5)), but understand
+!!!! Memory does not replace understanding. Do not memorise (equ.4) and (equ.5), but understand
 !!!! the definitions of the object and image focal points, and know how to find these two equations 
 !!! from the conjuction equation for a spherical refracting surface.
 !!!!
 
-! *NOTE* :<br>
-! An optical element being convergent if the image focal point is real, 
-! so if $`\overline{OF}>0`$ (with optically axis positively oriented in the direction of the light propagation), 
-! you can deduce from (equ.4)) that is spherical refracting surface is convergent if and only if its center
+! *NOTE 1* :<br>
+! An optical element being convergent when the image focal point is real, 
+! so when $`\overline{OF}>0`$ (with optically axis positively oriented in the direction of the light propagation), 
+! you can deduce from (equ.4) that is spherical refracting surface is convergent if and only if its center
 ! of curvature C is in the mmedium of highest refractive index.
 !
 
@@ -201,6 +201,13 @@ propagation of the light (from the object towards the refracting surface)
 \- **nodal point C = center of curvature**.<br><br>
 \- **object focal point F and image focal point F’**.
 
+! *NOTE 2*<br>
+! The direction of the curvature does not presume the convergent or divergent character
+! of the diopter. It also depends on the refractive index values on each side of the spherical 
+! refracting surface. look at what happens to the incident ray parallel to the optical axis 
+in Figures 6 and 7, and 8 and 9, and review NOTE 1.
+!
+
 
 #### Non stigmatism of spherical refracting surfaces