question_answer 33)

A parallel plate capacitor is to be designed with a voltage rating 1 kV, using a material of dielectric constant 3 and dielectric strength is the maximum electric field a material can tolerate without breakdown, i.e., without starting to conduct electricity through partial ionisation.) For safety, we should like the field never to exceed, say 10% of the dielectric strength. What minimum area of the plates is required to have a capacitance of 50 pF? 

Answer:

10% of the given field i.e., 107 V m?1                        gives E = 0.1 × 107 V m?1                 Using                 i.e.,  we get                                 Using C =                                                 = 19 cm2.