I keep getting “Coulomb's law” questions wrong in Electrostatics. What's the trap?
ignoring that like charges repel and unlike attract when assigning direction.
The usual trap: ignoring that like charges repel and unlike attract when assigning direction. How to avoid it: it mirrors gravitation but can be attractive OR repulsive. Go back to the definition — the force between two point charges, F = kq₁q₂/r², along the line joining them.
Key point
Coulomb's law
Common mistake
ignoring that like charges repel and unlike attract when assigning direction.
Memory tip
it mirrors gravitation but can be attractive OR repulsive.
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