Comparison of Capacitance

Physics 102

Comparison of Capacitance

Joseph Lan & Eduardo Nuñez

2/21/06

Abstract:

We are attempting to find out the permittivity of several materials and also determine the capacitive distance dependency between two charged plates that are parallel to each other.

Equipment:

  Decade capacitance box

  2 Decade resistor boxes

  Digital Voltmeter

  AC generator

  micrometer

  Various materials (supplied by instructor)

  Parallel plate capacitor apparatus

Procedure:

1)  Setup the circuit as shown on the lab manual, http://ccphysics.us/henriques/Ph102/comprcap102.htm.

2)  Measure the thickness of one of the materials with the micrometer and the area of the plate.

3)  Place the material in between the parallel plates.

4)  Set C1 and R3 to some small value

5)  Set the AC generator to sine wave, 1kHz, and high gain

6)  Adjust R4 until Voltage is as low as possible. (Note: it may be necessary to adjust C1 and R3 as well, but do not adjust them simultaneously.)

7)  Calculate C2 from the formula mentioned further below.

8)  Repeat steps 2-7 for all other materials

Calculations: (See Excel Sheet for actual results)

C = kЄo A

d

Cd = kЄo

A

Error Analysis:

׀Theoretical – Experimental ׀ X 100

׀ Theoretical ׀

Conclusion:

The purpose of this lab was to use our prior knowledge from previous labs to find the permittivity of several materials as well as finding the capacitive distance dependency between the two charged parallel plates. In doing so, we came to find that certain materials, as well as their thicknesses can affect how much charge can be store in these. Through the different trials we were able to show that that there is a clear relationship between the capacitance, the distance between the plate and how the slope of their relationship is depicted by the AЄo.

Grade = 70