Measurement of Self Inductance by Maxwell Bridge

  Procedure:

  1. Apply Supply voltage (3V) from the signal generator with arbitrary frequency.

  2. Select the type of the unknown Inductor (Air Core or Iron Core) from 'Set Inductor Value' tab by clicking on 'Set' button.

  3. Then switch on the supply to get millivoltmeter deflection.

  4. For Air Core experiment: Choose the values of R2, L2, r2, R3 and R4 from the control box below or directly put the values in the boxes of respective elements.

  5. Observe the millivoltmeter pointer to achieve "Null" or closest to "Null".

  6. If "Null" is achieved, switch to 'Measure Inductor Value' tab and click on 'Simulate'. Observe calculated values of unknown Inductor (L1) and unknown Internal Resistance (R1) of the Coil. Also observe the Quality factor (or Q-factor) of the coil, which is defined as `(omegaL)/r`. where, `w=2*pi*f`.

  7. For Iron Core experiment: Follow the same procedure from step 2 to step 6.

    8. N.B.:-  Range of L2 = 10uH to 111.1mH (in steps of 10uH ).
    Range of R2, R3 and R4 is 1`Ω` to 11.11111 MΩ (in steps of 1`Ω` ).
    Range of r2 = 0.01`Ω` to 11.11111 MΩ (in steps of 0.01`Ω` ).

Tutorials Point

Coil Select

Voltage:

Frequency:

V

Hz

H

`Ω`

`Ω`

`Ω`

`Ω`

`mV`

  • R1:

    L1:

    `Ω`

    mH

    Select the type of the unknown Inductor from the
    'Coil Select' box and click on the 'Set' button.
    Range of L1:      For Air Core: 45`mH`
                              For Iron Core: 450`mH`
    N.B.:- Range of L2 = 10uH to 111.1mH (in steps of 10uH ).
    Range of R2, R3 and R4 is 1ohm to 11.1 Mohm (in steps of 1ohm ).
    Range of r2 = 1ohm to 11.1 Mohm (in steps of o.5ohm ).

  • The current voltmeter reading is:   mv.
    Now click on simulate to get:
         Inductor value (in mH):
         Resistance value (in Ohm):
         Quality Factor:
CONTROLS
R2 : 1 Ohm   11.11111 MΩ
L2 : 10 uH   111.1mH
r2 : 1 Ohm   11.11111 MΩ
R3 : 1 Ohm   11.11111 MΩ
R4 : 1 Ohm   11.11111 MΩ