Which of the following is an example of an electrostatic type instrument?

Electrostatic Instrument

• The instrument which uses the static electric field for producing the deflecting torque is known as the electrostatic instrument. The electrostatic instrument is used for measuring the high and low voltage and also the power of the given circuit.
• Examples: Electrostatic Voltmeter, Electrostatic Charge Meter, Kelvin multicellular voltmeter, Electrostatic Galvanometer etc.
• The electrostatic instrument works on the principle of mechanical interaction of the electrodes that consists the opposite electrical charge. The quantity which is measured by the electrostatic instrument is converted into either AC or DC voltage.
• It consists of two plates, one plate is fixed while the other is free to move. The plates are oppositely charged, creating an attractive force that moves the movable plate towards the fixed plate until maximum electrostatic energy is stored.

Additional Information

• Energy meter and wattmeter are integrating type instruments. Integrating instruments measure the total amount of electricity or energy consumed over a specific period of time. 
• The hot wire ammeter is a device used to measure AC or DC current intensity based on the thermal expansion of a wire that is heated due to the flow of the electric current through it, as the heat produced is proportional to the square of DC or rms value of AC.