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An electrostatic fieldmeter, also called a static meter is a tool used in the static control industry. It is used for non-contact measurement of electrostatic charge on an object. It measures the force between the induced charges in a sensor and the charge present on the surface of an object.
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The alternating current signal produced by the flow of this charge is amplified and used as an analogue for the DC voltage applied to the capacitor. The DC input resistance of the electrometer is determined solely by the leakage resistance of the capacitor, and is typically extremely high, (although its AC input impedance is lower).
ESR meters fitted with protective diodes cannot be used, a battery will simply destroy the diodes and damage itself. An ESR meter known not to have diode protection will give a reading of internal resistance for a rechargeable or non-rechargeable battery of any size down to the smallest button cells which gives an indication of the state of charge.
In practice the conductivity cell is calibrated by using solutions of known specific resistance, ρ*, so the individual quantities l and A need not be known precisely, but only their ratio. [11] If the resistance of the calibration solution is R * , a cell-constant, defined as the ratio of l and A ( C = l ⁄ A ), is derived.
Coulometry is the measure of charge, thus named after its unit the coulomb. Michael Faraday, known for his work in electricity and magnetism, made critical contributions to the field of electrochemistry. He discovered the laws of electrolysis, and in his recognition is the eponym of the Faraday constant.
The charge control consists of a pressure switch built into the cell, which disconnects the charging current when the internal cell pressure rises above a certain limit; usually 200 pounds per square inch (1.4 MPa) to 300 pounds per square inch (2.1 MPa). This prevents overcharging and damage to the cell.
When used for measuring voltage, the input impedance of the multimeter must be very high compared to the impedance of the circuit being measured; otherwise circuit operation may be affected and the reading will be inaccurate. Meters with electronic amplifiers (all digital multimeters and some analog meters) have a fixed input impedance that is ...