I would like to know the mechanism of LCR bridge

[hjq_seu]

Who can tell me the theory about the LCR bridge to measure capacitance?

 

[berkeman]

Who can tell me the theory about the LCR bridge to measure capacitance?

Google to the rescue: lcr bridge measure capacitance

http://chem.ch.huji.ac.il/~eugeniik/instruments/test/bridges.html

 

[waht]

re

The ac bridges work just like the wheatstone bridge except you have to balance the impedance, which is dependent upon the frequency. By taking a ratio of impedances, you can calculate the capacitance or inductance as required.

The ac bridges are pretty much obsolete in modern test equipment. Today's LCR meters work by introducing a small sinusoidal voltage to a network (capacitor, inductor, resistor or combinations), and measuring the current that flows into the circuit. By the ohm's law, the impedance can be calculated Z = V/I, from which capacitance or inducance can be deduced.