EXPERIMENT
AIM
To find the value of unknown inductance using a Maxwell’s inductance bridge.
APPARATUS REQUIRED
 Trainer Kit
 Unknown inductance
 Multimeter
 CRO.
 Patch chords.
FORMULA USED
Note
In this bridge resistance R1 is for maximum variation of output and resistance R2 is for minute Variation of output.
PROCEDURE  I
 Connections are made as per the connection diagram shown above.
 Connect the unknown inductance at the Lx (unknown) point.
 Connect the CRO across P and Q.
 Switch ON the unit.
 Choose R3, such that you can obtain a maximum variation of output.
 Now set R2 to maximum position.
 Vary the potentiometer R1 such that the amplitude of sine wave will is decreases and that one point it will obtain a minimum of zero amplitude and then it will start increasing at that point stop the tuning and switch OFF the unit.
 Remove the patching at R1 and find the resistance using Multimeter and note down the reading according to the table given below and calculate the value of unknown inductance.
 One can verify the balancing condition by connecting the bridge output (P & Q) to the CRO balance the bridge output is zero . If you vary the potentiometer R1 you can hear a maximum voltage.
TABULATION
C = 0.1uF
SL NO

R1 ohms

R3 ohms

Lx practical

Lx theoretical






MAXWELL'S INDUCTANCE BRIDGE
PROCEDURE  II
 Connections are made as per the connection diagram shown above.
 Connect the unknown inductance at the Lx (unknown) point.
 Connect a multimeter in mV range (AC) across P & Q.
 Switch ON the unit.
 Choose R3, such that you can obtain a maximum variation of output.
 Vary the potentiometer R1 such that the output voltage will decrease and at one point it will obtain a minimum voltage and then start increase at this point stop the tuning and then vary R2. Here also the output voltage will decrease and at one point it will obtain a minimum voltage and then start increase at that point stop the tuning.
 Repeat the above step such that you will obtain minimum voltage or zero voltage.
 Remove the patching at R1 and find the resistance using multimeter and note down the reading according to the table given below and calculate the value of unknown inductance.
 One can verify the balancing condition by connecting the bridge output
TABULATION
C = 0.1uF
S. No

R1 (Ohms)

R3 (Ohms)

Lx (Theoretical)

Lx (Practical)






RESULT
Thus the value of unknown inductance was measured using Maxwell’s Inductance Bridge.