1. The problem statement, all variables and given/known data I want to calculate the lienard-wichert vector potential, based on the retarded potential expression given in Heald-Marion (classical electromagnetic radiation). 2. Relevant equations I get: A=v[tex]\Phi[/tex], where [tex]\Phi[/tex] is the lienard-wichert scalar potential and v is the charge velocity. I am missing a factor of 1/c. I think i'm probably making a stupid mistake somewhere in there, the problem looks really simple. I might be making the wrong variable change or something. 3. The attempt at a solution I get: A=v[tex]\Phi[/tex], where [tex]\Phi[/tex] is the scalar potential. Thanks!