A parallel plate capacitor has air in between the plates,which are circular with radius 0.07 m.The separation gap is 0.375 mm.What is the maximum energy that can be stored in this capacitor if air-breakdown is to be avoided? The breakdown threshold field is approximately 3 $\times$ 10⁶ N/C.

Question

Quizplus · Accepted Answer

The maximum energy that can be stored in a capacitor without air breakdown is given by $U=\frac{1}{2}\epsilon_0EA^2$, where $\epsilon_0$ is the permittivity of free space, $E$ is the breakdown threshold field, and $A$ is the area of the plates. Plugging in the given values, we get $$U=\frac{1}{2}(8.85	imes10^{-12})(3	imes10^{16})(\pi(0.07)^2)^2\approx2.3	imes10^{-15}	ext{ J}.$$ The closest answer choice is B.

A Parallel Plate Capacitor Has Air in Between the Plates,which ×\times×

A Parallel Plate Capacitor Has Air in Between the Plates,which $\times$