Uploaded by Mohammad Bilal Akram

DC and AC Bridges

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.[26] 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.