diff --git a/01.curriculum/01.physics-chemistry-biology/03.Niv3/01.nature light/01.electromagnetic-spectrum/01.new-course-main/textbook.en.md b/01.curriculum/01.physics-chemistry-biology/03.Niv3/01.nature light/01.electromagnetic-spectrum/01.new-course-main/textbook.en.md
index 536ac28bf..6aff3b811 100644
--- a/01.curriculum/01.physics-chemistry-biology/03.Niv3/01.nature light/01.electromagnetic-spectrum/01.new-course-main/textbook.en.md	
+++ b/01.curriculum/01.physics-chemistry-biology/03.Niv3/01.nature light/01.electromagnetic-spectrum/01.new-course-main/textbook.en.md	
@@ -4,6 +4,5 @@ published: no
 ---
 
 test :
-$`\oiint_S \vec{B} \cdot \vec{dS}`$
+$`\oiint_S \vec{B} \cdot \vec{dS}=0`$
 
-$`\Long\oiint_S \vec{B} \cdot \vec{dS}`$
\ No newline at end of file