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1 files changed, 1 insertions, 1 deletions

diff --git a/content/know/concept/spitzer-resistivity/index.pdc b/content/know/concept/spitzer-resistivity/index.pdc
index 6ceed8d..6be97cb 100644
--- a/content/know/concept/spitzer-resistivity/index.pdc
+++ b/content/know/concept/spitzer-resistivity/index.pdc
@@ -24,7 +24,7 @@ This can be modelled as a drag force $f_{ei} m_e v_e$,
 where $f_{ei}$ is the electron-ion collision frequency
 (we neglect $f_{ee}$ since all electrons are moving together),
 $m_e$ is their mass,
-and $v_e$ their typical velocity.
+and $v_e$ their typical velocity relative to the ions in the background.
 Balancing the two forces yields the following relation:
 
 $$\begin{aligned}