Q8Electronic Measurement & Instrumentation
Question
2 marks
Write down the three characteristics of detectors used in AC-bridge.
Answer
Detectors must have high sensitivity, good selectivity to reject harmonics, and appropriate impedance.
The null detectors (like headphones, vibration galvanometers, or tunable amplifiers) used in AC bridges must possess three key characteristics:
1. High Sensitivity: Must be able to detect extremely small unbalance currents or voltages.
2. Selectivity (Frequency Response): Must be highly tuned to the fundamental frequency of the bridge source to reject noise and harmonics that do not balance out.
3. Impedance Matching: Should have appropriate input impedance (low for current detection, high for voltage detection) to not load the bridge circuit.