Capacitor Energy W/ Different Dielectrics?
Two parallel plates are connected to a battery which maintains a constant potential difference of 17.0 V. The distance between the plates can be varied and there are three plates of different dielectric materials available: rubber (0.45 mm, κ = 6.7), glass (3 mm, κ = 7) and teflon (3 cm, κ = 2.1). The area of the plates is 100 cm2. What is the maximum energy that can be stored in the capacitor using one of the three materials?
Answers & Comments
Verified answer
For max energy, must have max capacitance.
So the ratio κ / d must be maximum => max κ and min d
Rubber wins easily.
C = 8.85*10^-12 * 6.7 * 100*10^-4 / 0.45*10^-3 = 1.32*10^-9 F
V = 17 V
Max energy = 0.5*C*V^2 = 1.90*10^-7 J