1. The problem statement, all variables and given/known data I want to know whether the magnitude of the charged electric field in the parallel plate-air capacitor is always delta/epsilon... In the last image, I have to put E=delta/2epsilon unlike the two situations above. What's the difference between the last one and the first two?? Why can't I put E=delta/epsilon?? The question is from 'young and freedman university physics' chapter 24. capacitance and dieleectrics question number 76. 3. The attempt at a solution mentioned above.