Hi everyone, I'm on a train using my phone, so apologies if this seems blunt. I'm looking at Coulombs law, but I don't understand part of it when the denominator is r squared. The r on the numerator has a squiggle above, which I do not understand. Similar to the r in the vector form equation here; http://en.m.wikipedia.org/wiki/Coulomb's_law#section_1 Thanks, Sparky
Well, I think you pretty much answered your own question about the R with the "squiggle". It's actually called a circumflex, and it denotes a unit vector. People would often read it as R(hat) or R-hat. It is the same as r-r1. The d^2 in the denominator means that charge is inversely proportional to the distance squared.