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Attracted-Disk Electrometer:

An attracted-disk electrometer is a fundamental instrument used to measure electric potential differences by observing the force of attraction between two oppositely charged disks. This instrument is used in electrostatics to measure high voltages and analyze the distribution of electric fields.

Key Components and Functionality:

  1. Disks:
  • The instrument consists of two parallel disks, one of which is movable. The fixed disk is connected to the object whose potential is being measured, while the movable disk is part of a sensitive weighing or force-measuring mechanism.
  1. Charging:
  • The disks are given opposite charges. The potential difference between the disks creates an electric field, resulting in an attractive force between them.
  1. Force Measurement:
  • The force of attraction between the charged disks is proportional to the square of the potential difference and inversely proportional to the square of the distance between them. By measuring the force required to keep the movable disk in a specific position, the potential difference can be determined.
  1. Calibration:
  • The electrometer is calibrated using known potential differences to ensure accurate measurements. The force measurement can be done using mechanical balances or more modern electronic sensors.

Importance in Measurement:

  • High Voltage Measurement: The attracted-disk electrometer is particularly useful for measuring high voltages in laboratory settings and for calibrating other instruments.
  • Educational Tool: It serves as a demonstration of electrostatic principles, showing the relationship between electric potential, electric fields, and forces.
  • Research Applications: Used in experimental physics to study electrostatic phenomena and to develop and test new materials and technologies involving electric fields.

Historical Context:

  • The attracted-disk electrometer is one of the earliest types of electrometers and played a significant role in the development of electrostatic measurement techniques. Its principles are still applied in modern instruments, although electronic and digital methods have largely replaced mechanical systems for practical applications.

In summary, the attracted-disk electrometer is a classic instrument that illustrates the principles of electrostatics and provides a means for measuring electric potential through the interaction of charged surfaces.

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