Answer to Question #94008 in Electric Circuits for rafey

Question

In the expression F=k qq/r2 why k=1/4pi epsilon

Answer 1

Many electrodynamic formulas include a $4\pi$ factor. To get rid of it in the practical and the most important formulas, the coefficient k is set equal to $\frac{1}{4\pi \epsilon_0}$ The modified formula is thus called rationalized.