The three main parts of the PH meter's structural composition
1, A reference electrode; and
2, a glass electrode whose potential depends on the pH of the surrounding solution; and
3, a galvanometer which is capable of measuring small potential differences in a circuit of very high resistance.
The following are the main functions of each component respectively:
1, the basic function of the reference electrode is to maintain a constant potential as a control for measuring various deviations from the potential. Silver - silver oxide electrode is currently zui commonly used reference electrode in pH.
2, the function of the glass electrode is to establish a potential difference in response to changes in the hydrogen ion activity of the measured solution. The pH-sensitive electrode and reference electrode in the same solution, on the formation of a primary battery, the battery potential is the glass electrode and the reference electrode potential of the algebraic sum of the E battery = E reference E glass, if the temperature is constant, the potential of this battery with the pH of the solution to be measured and change, and the measurement of pH meter in the battery generated by the potential is difficult, because of its potential is very small, and the circuit's impedance and Very large 1-100MΩ; therefore, the signal must be amplified so that it is sufficient to drive the standard millivoltmeter or milliammeter.
3, the function of the ammeter is to amplify the potential of the original battery a number of times, the amplified signal is displayed through the meter, the degree of deflection of the meter pointer indicates that the strength of the signal to promote the use of the needs of the pH ammeter dial engraved with the corresponding pH value; and digital pH meter is directly to the digital pH value.
