Q1Electronic Measurement & Instrumentation
Question
What is absolute and secondary instruments ?
Answer
Absolute instruments give values in terms of physical constants; secondary instruments provide direct readings and require calibration.
- Absolute Instruments: These instruments give the magnitude of the quantity being measured directly in terms of the physical constants of the instrument and its deflection. They do not require calibration against any other standard. (Example: Tangent Galvanometer, Rayleigh's Current Balance).
- Secondary Instruments: These instruments have a pre-calibrated scale that directly indicates the value of the electrical quantity. They must be calibrated initially by comparing them with an absolute instrument or another primary standard. (Example: Standard voltmeters, ammeters, multimeters).