A parallel-pate capacitor is made of two flat metallic plates of area 4 cm2 at a distance of 1 mm. It is filled by air (that is equivalent to vacuum for our purpose). If you apply a voltage of 10 V, what is the energy stored in the capacitor?
(a) Use the formula based on integrating the electric field inside
(b) use the formula where you use the value of the capacitor