Balance indicator:
An earphone could act as a balance indicator if the frequency of the ac source is in audio-range.
- A magic eye, that provides a green fluorescence as a result of electrons striking a phosphor coating within the glass tube, is used in various commercial instruments.
- To much precise conductance measurements a cathode ray oscilloscope is used as the balance indicator.
Figure: A conductivity bridge circuit
Conductance (G=1/Rx) can be read directly on commercially available instruments as a panel mounted meter. Now various digital instruments are also available, like instruments provides the conductance directly as the numerical value.