# Maxwell-Wien Bridge or Maxwell’s L/C Bridge

- Sep, 29, 2012
- Electronics Project Admin
- Electronics tutorials
- 2 Comments.

Maxwell bridge measure an unknown inductance in term of known capacitance. The two opposite ratio arms consists pure resistance, while one of the ratio arms has a resistance and capacitance in parallel and last arm of bridge has a resistance and unknown inductance in series. The positive phase angle of inductive impedance may be compensated by the negative phase angles of capacitive impedance put in the opposite arm.

Z_{1}, Z_{2}, Z_{3} and Z_{4} are the impedance of the arm AB, BC, CD, and DA respectively.

Let us first find the combined impedance of arm AB.

**Z _{1} = R_{1}||X_{C}**

**Z _{3} = R_{3} + jωL_{3}** and

**Z**

_{4}= R_{4}Balance condition is **Z _{1}Z_{3} = Z_{2}Z_{4}**

Or, **R _{1}R_{3}+jωL_{3}R_{1} = R_{2}R_{4} + jωCR_{1}R_{2}R_{4}**

Separating the real and imaginary, we get

**R _{1}R_{3} = R_{2}R_{4} and L_{3}R_{1} = CR_{1}R_{2}R_{4};**

**L _{3} = CR_{2}R_{4}**