Update textbook.fr.md

12.temporary_ins/96.electromagnetism-in-media/20.reflexion-refraction-at-interfaces/20.metallic-waveguides/10.main/textbook.fr.md

@@ -15,13 +15,16 @@ main char- acteristic of this kind of propagation. We will introduce a
 We have seen in the previous chapter that the oblique incidence of
 plane waves on planar conductive materials gives rise to an
 interference pattern between the incident and reflected waves such
-that the resulting wave has propagating character along the *z* axis
-and a standing wave pattern along the *y* axis. 
+that the resulting wave has propagating character along the z axis
+and a standing wave pattern along the y axis. 
 
 ![](TE-and-TM-waves-1_L1200.jpg)   
 _TE and TM waves and their corresponding standing wave behaviour along the y axis._
 
-For TE modes we have:
+
+For TE modes (TE = transverse-electric) we have:
+
+_equations_
 
 <!------------
 []{#_bookmark79 .anchor}$`\overrightarrow{E}`$~⊥~ = −2*E*~0~ sin (*k y* cos *θ*) sin
@@ -63,13 +66,18 @@ height="1.7708333333333333in"}
 standing wave be- haviour along the *y* axis.
 ---------->
 
+and similarly for TM modes  (TM = transverse-magnetic)
+
+_equations_
 
 These results are dictated by the boundary conditions at the air-metal
-inter- face which impose that for every point on the boundary surface
+interface which impose that for every point on the boundary surface
 and for all times the tangential component of the electric field
 (incident + reflected) and the perpendicular component of the
-induction field (incident + reflected) to be zero: $`\overrightarrow{E}_{\parallel}`$*~t~* = 0 and
-$`\overrightarrow{B}_{\perp}`= 0`$.   
+induction field (incident + reflected) to be zero:   
+
+$`\overrightarrow{E}_{\parallel}=0\quad\text{and}\quad\overrightarrow{B}_{\perp}=0`$.   
+
   
 For TE modes this results in the fact that the total electric field
 $`\overrightarrow{E}`$~⊥~ (it is