Kelvin Double Bridge

Main dial
The variable arm of the bridge consists of a decade resistance dial of 0.01 ohms Step (0.01-0.1 ohm)

Slide wire dial (white scale)
A graduated slide wire scale is divided in 500 equal parts; the value of one scale division at multiplier 1 is 0.00002 ohms or 0.02 m.

Multiplier
A range multiplier consists of double ratio box giving multiplying factor of 0.01, 0.1,1,10 & 100 The value of unknown resistance is given by the sum of main dial & slide wire readings multiplied by multiplier used to measure the unknown resistance.

Current reversing switch
A current reversing switch is incorporated to eliminate the difference of readings due to thermo electric e.m.f. A measurement of resistance is to be taken with the direction of current reversed.

Press keys
Two press keys marked initial and final are given for galvanometer. And one press key marked DC SOURCE is given for DC source which start and stop the current to flow in the instrument and unknown resistance under test. This press key is provided to avoid the excessive heating.

Optional Acc:

1. DC Source 0-12VDC/10A
2. Galvalnometer 30-0-30 Division Sensitivity of 2µA/Division
3. Conductivity Attachment
4. Connecting Leads (current carrying capacity 10Amps)