While reading through the Feynman Lectures on Physics (volume 1, number 28) I have come across the formula for the electric field for a moving point charge - it's the equation labelled (1) on this page: http://maxwellsociety.net/PhysicsCorner/InteractingParticles/AcceleratingCharges.html Can anyone explain where this comes from? The first term I recognise as Coulomb's law, but am right in thinking that the second accounts for the time it takes for the change in electric field to propagate to an observer? And then where does the last term come from? Do I need to just take this on faith until I get to volume 2? Thanks for any help!