Let’s say I have a positive electric charge in middle of two plates, one is positively charged, the other one negatively with total intensity of electric field of 5 N/C. If the charge has 2 Coulombs, and is 3 meters from positive plate and 3 meters from negative plate, it will have potential energy relative to negative terminal 30 Joules, right?
But what potential energy will that charge have relative to the positive plate? -30 Joules? And what does that even mean? Can we speak of potential energy when comparing the positive charge with positive plate?