The dielectric in a capacitor serves two purposes. It increases the capacitance,
ID: 1535245 • Letter: T
Question
The dielectric in a capacitor serves two purposes. It increases the capacitance, compared to an otherwise identical capacitor with an air gap, and it increases the maximum potential difference the capacitor can support. If the electric field in a material is sufficiently strong, the material will suddenly become able to conduct, creating a spark. The critical field strength, at which breakdown occurs, is 3.0 MV/m for air, but 60 MV/m for Teflon
A parallel-plate capacitor consists of two square plates 17 cm on a side, spaced 0.60 mm apart with only air between them. What is the maximum energy that can be stored by the capacitor? The answer to this part is 6.9x10^-4.
but I can't figure out this part...
What is the maximum energy that can be stored if the plates are separated by a 0.60-mm-thick Teflon sheet? Answer in joules
Explanation / Answer
Part B
The plate area = 0.17 * 0.17
A= 28.9x10-3 m2
For Teflon:
The voltage is:
V = 60x106* 600x10-6
V = 36*103
V = 36 kV
The capacitance is:
C = *A/d
C = 2.1*8.854x10-12 * 28.9x10-3/600x10-6
C = 8955x10-12 F
C = 8955 pF
The maximum energy stored is:
E = ½ CV2
E = 0.5* 8955x10-12* (36x103)2
E = 5802*10-3 J
E = 0.58 J