RU1807373C - Method of determination of dielectric permittivity of substances - Google Patents

Abstract

Field of use: scientific and applied research in the field of chemistry, physics, biology, medicine. SUMMARY OF THE INVENTION: A measuring circuit is formed from a series-connected measuring capacitor and resistance. The voltage at the input of the circuit and at the measuring capacitor is measured, three measurement cycles are carried out at two frequencies: when the measuring capacitor is empty, when it is filled with a reference liquid and when the measuring capacitor is filled with the test liquid. The dielectric constant of the liquid is determined from the measurement results. 1 ill.

Description

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WITH

The invention relates to the field of measurement technology, in particular to dielectric control methods and can be used in various fields of chemistry, physics, biology, medicine.

The purpose of the invention is to improve the accuracy of the measurement method in determining the dielectric constant of a liquid.

The method is implemented in the following sequence of operations.

Serial measuring capacitor connect additional resistance.

Three measurement cycles are carried out, in each of which they measure:

- voltage at the input of the measuring circuit resistance-measuring capacitor at a frequency fi;

- the same at frequency h:

- voltage at the measuring capacitor at a frequency f i;

- the same at frequency f2.

In the first cycle, the parameters of the unfilled capacitor are determined. In the second cycle, the capacitor is filled with a reference fluid. In the third cycle, the capacitor is filled with the test liquid. According to the measurement results calculate the value of B by the formula:

with

ABOUT

xi

GO XI

with

V k $ - k t (Јэ -1) (lkS2-kii 12

vXEZlr 1 ..- i

| kfc-kii

where EE is the dielectric constant of the reference fluid:

ki Uoi / Ui; k2 Uo2 / U2.

where Ui and Da are the voltages across the capacitor filled with the test liquid, at the frequencies fi and fa of the input signal;

Uoi, Uo2 - also at the input of the measuring circuit;

KE1 Uoal / Uai; KE2 and OE2 / IE2, where IE1, 11E2 are the voltages across the capacitor filled with the reference fluid at the input signal frequency f 1 and f2;

Uoal, Uoa2 - also at the input of the measuring circuit.

ky Uobi / Ubi; kb2 Uob2 / Ub2, where Ubi, Ub2 are the voltages on the unfilled capacitor at the frequencies fi and h of the input signal;

Mustache, Uob2 - also at the input of the measuring circuit.

A device implementing the method for determining the dielectric constant is shown in the drawing.

The device contains sinusoidal voltage generators 1, 2 with frequencies f 1 and f2, respectively, key 3, additional resistance .4, measuring cell 5 with filling medium 6, capacitor plates 7, 8, and voltage meters 9 and 10.

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Claims (1)

In the first cycle, medium 6 is absent. The key 3 is alternately set in the connecting position of the generator 1 and the generator 2. The voltage at the input of the measuring circuit is measured by the resistance of the 4-capacitor by meter 9. In the second cycle, sample liquid is used as medium 6 in the second cycle. In the third cycle, the test fluid. SUMMARY OF THE INVENTION A method for determining the dielectric constant of substances, which means that voltages are measured on an unfilled and filled measuring capacitors at two input signal frequencies, characterized in that, in order to increase the accuracy of determining the dielectric constant of a liquid, additional measurements are made on those at the same frequencies when the capacitor is filled with a reference fluid, and in all cycles, the voltage at the input of the circuit composed of a capacitor is measured and connected in series resistance, and the dielectric constant of the liquid is determined as the result of joint measurements. 4 -Si - / /