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1 files changed, 3 insertions, 3 deletions

diff --git a/content/know/concept/einstein-coefficients/index.pdc b/content/know/concept/einstein-coefficients/index.pdc
index b56af77..d50235f 100644
--- a/content/know/concept/einstein-coefficients/index.pdc
+++ b/content/know/concept/einstein-coefficients/index.pdc
@@ -5,9 +5,9 @@ publishDate: 2021-07-11
 categories:
 - Physics
 - Optics
-- Electromagnetism
 - Quantum mechanics
 - Two-level system
+- Laser theory
 
 date: 2021-07-11T18:22:14+02:00
 draft: false
@@ -275,7 +275,7 @@ $$\begin{aligned}
     \boxed{
         B_{21} = B_{12} = \frac{\pi |d|^2}{\varepsilon_0 \hbar^2}
         \qquad
-        A_{21} = \frac{\omega_0^3 |d|^2}{\pi \varepsilon \hbar c^3}
+        A_{21} = \frac{\omega_0^3 |d|^2}{\pi \varepsilon_0 \hbar c^3}
     }
 \end{aligned}$$
 
@@ -332,7 +332,7 @@ $$\begin{aligned}
     \boxed{
         B_{21} = B_{12} = \frac{\pi |\vec{d}|^2}{3 \varepsilon_0 \hbar^2}
         \qquad
-        A_{21} = \frac{\omega_0^3 |\vec{d}|^2}{3 \pi \varepsilon \hbar c^3}
+        A_{21} = \frac{\omega_0^3 |\vec{d}|^2}{3 \pi \varepsilon_0 \hbar c^3}
     }
 \end{aligned}$$