Capacitor separated by a dielectric

[EngineerHead]

Homework Statement

REFER TO ATTACHED SCREEN SHOT

Homework Equations

The Attempt at a Solution

My discrepancy is with the last question labeled "Exercise" (What is the maximum energy that can be stored in the capacitor?).

Since the max voltage is 16000V = 16000 J/C, why is multiplying the max voltage by the max charge (3.2 e-7 C) incorrect?

 

[NewtonianAlch]

The energy contained is U = 1/2*C*V^2

 

[NascentOxygen]

why is multiplying the max voltage by the max charge (3.2 e-7 C) incorrect?

Because were you to start drawing off charge, the capacitor voltage would drop, so you don't have available that amount of charge at the max charged voltage.