DC Bridges Wheat·stone bridge a simple circuit for measuring an unknown resistance by connecting it so as to form a quadrilateral with three known resistances and applying a voltage between a pair of opposite corners. Rx= R2R3/R1= R4 Kelvin bridge A Kelvin bridge, also called a Kelvin double bridge and in some countries a Thomson bridge, is a measuring instrument used to measure unknown electrical resistors below 1 ohm. It is specifically designed to measure resistors that are constructed as four terminal resistors A.C Bridges Maxwell bridge A Maxwell bridge (in long form, a Maxwell-Wien bridge) is a modification to a Wheatstone bridge used to measure an unknown inductance (usually of low Q value) in terms of calibrated resistance and capacitance. It is a real product bridge. Opposite Angle Bridge/hay's bridge It is a four-arm alternating-current bridge used to measure inductance in terms of capacitance, resistance, and frequency; bridge balance depends on frequency. Wien bridge oscillator The oscillator is based on a bridge circuit originally developed by Max Wien in 1891 for the measurement of impedances. Wien's bridge is used for precision measurement of capacitance in terms of resistance and frequency. It was also used to measure audio frequencies. Schering Bridge Theory This bridge is used to measure to the capacitance of the capacitor, dissipation factor and measurement of relative permittivity.