Residual capacitance relation with measured data

[rockerman]

Homework Statement

Hello everyone!

I'm writing a lab report about capacitance of a capacitor of mobile parallel plates. The experiment guide says to measure the capacitance when the distance tends to infinity. This is the residual capacitance, which in my measurings result in 5pF.

Ok... the area of the plates is 7.85 x 10^-3... and I'm using the C = A* epsilon_0/d formula to estimate the capacitance

below the Measured data and the theoretical one:

measured: (distance(mm) ; capacitance (pF))

1:85 2:40 3:29 4:23 5:20 6:17 7:15 8:14 9:13.5 10:13

calculated (distance(mm): capacitance(pF))

1:69.42 2:34.713 3:23.1423 4:17.3568 5:13.8854 6:11.5712 7: 9.9181 8:8.6784 9:7.7141 10:6.9427



Is this mere coincidence that the values differ in majority by about 5pF?

my doubt is if this residual capacitance will not be included in the theoretical model?

thanx...

 

[jbsteele]

Homework Equations C = A* epsilon_0/dThe Attempt at a SolutionYes, the residual capacitance should be included in the theoretical model. It is likely that the residual capacitance is due to other factors such as air dielectric, surface roughness, and imperfections in the plates. These all contribute to the total capacitance of the capacitor. Therefore, the residual capacitance should be added to the theoretical model to get a more accurate estimation of the capacitance.