When the judge asks you a question, you WILL be under oath.
Having gone to traffic court for tickets several times before, the only questions I have ever been asked by the judge is the standard "Your Name?" "Do you dispute this ticket?" Then the judge would call the ticketing officer to the stand who would give his side. "At 3:42 PM Wednesday the 22, I observed the defendent texting....etc" Then I would have an opportunity to question him. The judge isn't permitted to ask "Did you do it?", "Were you on a cell phone?" (that would be forced self incrimination).