# Maxwells inductance bridge

Posted by Circuits Arena on Friday, 22 August 2014

Maxwells inductance bridge is the artlcle explaining Maxwells inductance bridge The bridge circuit is used for medium inductance and can be arranged to yield results of considerable precisi...

###
Maxwells inductance bridge

The bridge circuit is used for medium inductance and can be arranged to yield results of considerable precision. As shown in figure 1, in the two arms, there are two pure resistances so that for balance relations, the phase balance depends on the remaining two arms. If a coil of unknown impedance Z_{1}is placed in one arm, then its positive phase angle ɸ

_{1}can be compensated for in either of the following two ways:

- A known impedance with an equal positive phase angle may be used in either of the adjacent arms (so that
**ɸ**, remaining two arms have zero phase angles (being pure resistances). Such a network is known as Maxwell’s a.c. bridge or_{1}= ɸ_{2}or ɸ_{1}= ɸ_{4})**L**bridge._{1}/L_{4} - Or an impedance with an equal negative phase angle (i.e. capacitance) may be used in opposite arm (so that
**ɸ**). Such a network is known as Maxwell-Wien bridge or Maxwell’s L/C bridge._{1}+ ɸ_{3 }= 0

**Z**

_{1}= R_{1}+ jX_{1}= R_{1}+ jωL_{1}…….unknown;**Z**

_{4}= R_{4}+ jX_{4}= R_{4}+ jωL_{4}….…known;
R

The inductance L_{2},R_{4}= known pure resistances; D = detector_{4}is a variable self-inductance of constant resistance, its inductance being of the same order as L

_{1}. The bridge is balanced by varying L

_{4}and one of the resistance R

_{2}or R

_{3}. Alternatively, R

_{2}and R

_{3}can be kept constant and the resistance of one of the other two arms can be varied by connecting an additional resistance in that arm.

The balance condition is that

**Z**

_{1}Z_{3}= Z_{2}Z_{4}**(R**

_{1}+ jωL_{1})R_{3}= (R_{4}+ jωL_{4})R_{2}**Z**

_{1}= R_{1}+ jX_{1}= R_{1}+ jωL_{1}…….unknown;**Z**

_{4}= R_{4}+ jX_{4}= R_{4}+ jωL_{4}….…known;
R

The inductance L_{2},R_{4}= known pure resistances; D = detector_{4}is a variable self-inductance of constant resistance, its inductance being of the same order as L

_{1}. The bridge is balanced by varying L

_{4}and one of the resistance R

_{2}or R

_{3}. Alternatively, R

_{2}and R

_{3}can be kept constant and the resistance of one of the other two arms can be varied by connecting an additional resistance in that arm.

The balance condition is that

**Z**

_{1}Z_{3}= Z_{2}Z_{4}**(R**

_{1}+ jωL_{1})R_{3}= (R_{4}+ jωL_{4})R_{2}
Subscribe to:
Post Comments (Atom)

## 0 Response to "Maxwells inductance bridge"