eutech-instruments cyberscan con 10 conductivitytds meter Manual Do Utilizador

53

In general, conductivity is a value that represents how easily electrical charges can be

transported through a conductor. Conductors are substances that permit the movement of

electrical charge with relative ease.

Figure 39 shows a conductivity cell. It is an electrochemical cell for measuring the conductivity

of an electrolyte solution. This cell consists of two electrodes; an anode and a cathode,

separated by an electrolyte solution. The two electrodes are in the shape of plates of identical

size, both having an identical surface area of A cm

2

. They are aligned parallel and are

separated by the distance, L. The space between them is filled completely with water-soluble

electrolyte solution. Alternating current flows through both electrode plates.

The negatively charged ions (anions) in the electrolyte migrate towards the anode and the

positively charged ions (cations) move towards the cathode. The result is the flow of electrical

current by ion movement.

The resistance to the movement of the charge between the two electrodes is inversely

proportional to their surface area and in direct proportion to their surface and also in direct

proportion to the distance between them. This is true for both electron movements in the metal

electrodes and ion movement in electrolytes. This relationship may be expressed by the

equation below.

               R = r. (L/A) = r.k               Equation  1