bridge-type impedance meter meaning

• [Electronics]
  An impedance-measuring circuit in which unknown impedance Zis connected in series with a calibrated variable resistor R. An ac voltage is applied to the series circuit. The separate voltage drops across the resistor and impedance are measured successively as the value of R is varied. When the two voltage drops are identical, Z equals R, and the impedance can be read from a calibrated dial on the variable-resistor control.