What is a Electrometer?

It is a measuring instrument that can accurately measure potential, voltage, etc. by measuring the potential difference between two points in the circuit. By using the electrostatic attraction and electrostatic repulsion between charged conductors, it is possible to measure without taking current from the circuit. Typical types are quadrant electrometers and vibration capacitance electrometers. The quadrant electrometer measures with a movable piece of metal (the discs divided into four are suspended by a wire), and in addition to the potential, a small current and a low power rate (power consumption during power supply). It can also be used for measurement such as (indicator of low effective utilization rate). The vibration capacitance electrometer is a mechanism that converts a direct current input into alternating current by changing the electrical capacity in parallel with the input, then further amplifies it and reads the output. However, digital multimeters have become widely used in recent years because they require skill in handling.

Application of Electrometer

The electrometer is used in the following cases. (1) I want to measure the electromotive force of a power supply with high internal resistance. (2) When the voltage is high but the current cannot be taken, such as the pressure electricity of crystals and triboelectricity. (3) When the anode and cathode are polarized even if a current can be passed, and the accurate value of the electromotive force cannot be measured. The type of potential meter is vibration capacitance type (by vibrating the electrode of the input capacitor, the voltage is applied to the electric circuit from the power supply or other circuits, and it is converted to an AC voltage proportional to the applied DC voltage and AC amplified). , Direct-coupled amplification type (using electric field effect transistor or capacitor vacuum tube). Compared to general voltmeters, the input resistance is extremely high at 1014 to 1016Ω, so it is used for measuring potential, insulation resistance, electric charge, minute current, etc. in fields such as radiation, static electricity, and insulating materials.

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