1. The problem statement, all variables and given/known data Consider the situation shown in the figure. The width of each plate is b. the capacitor plates are rigidly clamped in the lab and connected to a battery of emf E. All surfaces are frictionless. Calculate the value of M for which the dielectric will stay in equilibrium. 2. Relevant equations Tension T = mg Force due to electric field = tension Capacitance = KAε/d 3. The attempt at a solution What I don't get is how the electric field could pull the dielectric. The field is vertical, and the tension is horizontal, so shouldn't the dielectric just slide off? What force could possibly act in the horizontal direction other than tension?