Determining the relative permitivity of thin sheet material

Date

4-1993

Degree

Bachelor of Science in Applied Physics

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Edvino G. Eusebio

Abstract

To determine the relative permittivity or dielectric constant of thin sheet materials. whose thickness do not exceed 2.75 mm.. two capacitance transducers were developed. The circuit was based on charge transfer principle. One was was for measuring the thickness of the material and the other was for measuring the resulting capacitance. To sense these two quantities simultaneously, a differential capacitor was constructed. Test results showed that the response of the thickness transducer is not linear. Its sensitivity increased with thickness. The lowest sensitivity obtained was 0.27 v/mm. To predict the thickness given the output voltage, a curve fitting method was performed. The response of the capacitance transducer is linear. It had two settings. The first setting could measure 0 to 49 pF with a mean sensitivity of 0.144 v/pF. The second could measure 0 to 715 pF with a mean sensitivity of 0.014 v/pF. A computer program was developed for computing the relative permittivity given the two voltage outputs of the transducers. For paper, plastic, wood and cloth as samples, the dielectric constant yielded to 1.87, 1.23, 3.1 and 1.18, respectively.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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