Weston Cell

Definition

The Weston cell is a type of standard electrochemical cell that is used as a reference for voltage measurements. It is named after its inventor, Edward Weston, and is known for its stability and reproducibility, making it a valuable tool in null measurements and electrical calibration.

5 Must Know Facts For Your Next Test

1. The Weston cell uses a saturated solution of cadmium sulfate (CdSO4) as the electrolyte, with a cadmium electrode and a mercury-cadmium amalgam electrode.
2. The Weston cell has a very stable voltage of 1.0183 volts at 20°C, making it an excellent reference for voltage measurements.
3. Weston cells are designed to be portable and durable, allowing for their use in field measurements and calibration of electrical instruments.
4. The Weston cell is considered a primary standard, meaning its voltage can be reproduced with a high degree of accuracy and precision.
5. The temperature coefficient of the Weston cell is very low, allowing for accurate measurements over a wide range of temperatures.

Review Questions

• Explain how the Weston cell is used in null measurements.
  • The Weston cell is used as a reference voltage in null measurements, where an unknown voltage is compared to the known and stable voltage of the Weston cell. By adjusting the unknown voltage until the difference between it and the Weston cell voltage is zero, the unknown voltage can be accurately determined. This makes the Weston cell an essential tool for calibrating and testing electrical instruments, as well as for making precise voltage measurements in various applications.
• Describe the key features of the Weston cell that make it a reliable voltage standard.
  • The Weston cell has several features that contribute to its reliability as a voltage standard. Firstly, its voltage is highly stable at 1.0183 volts, with a very low temperature coefficient, allowing for accurate measurements over a wide range of temperatures. Secondly, the cell is designed to be portable and durable, making it suitable for use in both laboratory and field settings. Additionally, the Weston cell is considered a primary standard, meaning its voltage can be reproduced with a high degree of accuracy and precision, making it a valuable reference for calibrating and testing electrical instruments.
• Analyze the role of the Weston cell in the development of electrical measurement and instrumentation.
  • The Weston cell has played a crucial role in the development of electrical measurement and instrumentation. As a stable and reproducible voltage standard, the Weston cell has enabled the calibration and testing of a wide range of electrical devices, from voltmeters and ammeters to more complex instrumentation. This has been essential for ensuring the accuracy and reliability of electrical measurements, which are fundamental to many scientific, engineering, and industrial applications. The Weston cell's contributions to the field of electrical metrology have been instrumental in the advancement of technology and the pursuit of precise and reliable electrical measurements.

Related terms

Null Measurement:

A null measurement is a technique used to determine an unknown quantity by adjusting a known quantity until the difference between the two is zero, or 'null'.

Electrochemical Cell: An electrochemical cell is a device that converts the energy of a spontaneous chemical reaction into electrical energy, or uses electrical energy to drive a non-spontaneous chemical reaction.

Voltage Standard: A voltage standard is a device that provides a stable and accurate reference voltage, used to calibrate and test electrical instruments and devices.