1. The problem statement, all variables and given/known data a slab of some insulator with an unknown permittivity ε. To determine ε experimentally I go to the lab and insert the slab in between the plates of a capacitor whose plate spacing exactly matches the width of the slab. I observe that the time constant of exponential decay of the capacitor voltage in an RC circuit that I construct increases by 25% when the slab is inserted to replace the air spacing. Determine ε in terms of εo. Explain your reasoning carefully. 2. Relevant equations The problem is, I'm having troube finding a place to start. We are learning about d'Alembert wave solutions, Poynting theorem, TEM waves and such. 3. The attempt at a solution I first thought of using the solution to the differencial equation with the decay model but that doesn't seem to help me Can anyone point me in the right direction as to where to start with this problem? Any help is greatly appreciated.