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1 files changed, 7 insertions, 3 deletions

diff --git a/content/know/concept/electromagnetic-wave-equation/index.pdc b/content/know/concept/electromagnetic-wave-equation/index.pdc
index 68fe062..84946bb 100644
--- a/content/know/concept/electromagnetic-wave-equation/index.pdc
+++ b/content/know/concept/electromagnetic-wave-equation/index.pdc
@@ -118,14 +118,18 @@ $$\begin{aligned}
     \vb{E}(\vb{r}, t)
     &= \vb{E}_0 \exp\!(i \vb{k} \cdot \vb{r} - i \omega t)
     \\
-    \vb{H}(\vb{r}, t)
-    &= \vb{H}_0 \exp\!(i \vb{k} \cdot \vb{r} - i \omega t)
+    \vb{B}(\vb{r}, t)
+    &= \vb{B}_0 \exp\!(i \vb{k} \cdot \vb{r} - i \omega t)
 \end{aligned}$$
 
-In fact, thanks to linearity, these solutions can be treated as
+In fact, thanks to linearity, these **plane waves** can be treated as
 terms in a Fourier series, meaning that virtually
 *any* function $f(\vb{k} \cdot \vb{r} - \omega t)$ is a valid solution.
 
+Keep in mind that in reality, $\vb{E}$ and $\vb{B}$ are real,
+so although it is mathematically convenient to use plane waves,
+in the end you will need to take the real part.
+
 
 ## Non-uniform medium