From David J. Griffiths "Introduction to Electrodynamics 2. ed":
"The third term" is further up the page.Quote:
We're interested in the regime (...), so the third term is necligible, and the binomial expansion yields
What is really going on here? I've been trying to understand it, but I can't figure it out. How does he get ?
This is a step in deriving the formula
which in turn leads to