Measurement of Low Resistance by Kelvin Double Bridge

  Procedure:

  1. Set the voltage (V=12V) and switch on the board. Keep Switch(S) in 'Short' mode and adjust the rheostat(Rs) to maintain the current 2A, 3A, 4A or 5A in the circuit.

  2. Then set Switch(S) to 'Open' mode and set Low resistance(S) value within 0.001 to 0.01 ohm from 'Set The Unknown Resistance 'S'' box.

  3. Then set Switch(S) to 'Bridge' mode and Switch(K) to 'Open' mode.

  4. Vary the values of RA, RB, Ra and Rb from the control box below or directly put the values in the boxes of respective elements to get a zero deflection on the millivoltmeter pointer.

  5. Now, set Switch(K) to 'Close' mode and again vary the values of RA, RB, Ra and Rb to get a zero deflection on the millivoltmeter pointer.

  6. If "NULL" is achieved, click on 'Calculate' on 'Calculated Unknown Resistance Value' box to observe calculated value of unknown resistance (S).

Tutorials Point

Calculated Unknown Resistance Value



Set The Unknown Resistance 'S'

   0 0.01 Ohm

CONTROLS
   RA : 1 Ohm     1000 Ohm
   RB : 1 Ohm     1111 Ohm
   Ra : 1 Ohm     1000 Ohm
   Rb: 1 Ohm     1111 Ohm