Wheatstone bridge method for measurement of medium resistance

Wheatstone bridge

Wheatstone bridge- Balanced Bridge condition

R1/R2=R3/R4

I1=I3 and I2=I4

Vbc=Vde and Vab=Vad

Vbc=I3R3

Vdc=I4R4

As        Vbc=Vdc

I3R3=I4R4

I3/I4=R4/R3

Vab=I1R1 and Vad= I2R2

As        Vab=Vad

I1R1=I2R2

I1/R2=I2/R1

As        I3=I1 and I2=I4

I3/I4=I1/I2

R4/R3=R2/R1

R1/R2=R3/R4

R3=R4×R1/R2      (Proved)

 Advantages-

  1. It can measure the medium range resistance (1 Ω <R<1 kΩ).
  2. The design is comparatively simpler compared to another bridge circuit.
  3. Calculation and complexity are less.

Disadvantages-

  1. Resistance value below 1Ω can’t be measured with this circuit.
  2. During the calculation of low resistance with the help of Wheatstone bridge, we can observe most of the voltage drop across the wire connections and the joint points by which the wire resistance becomes higher than the circuit resistance and it produce error while we measure low resistance value.

 

Also Read- Measurement of resistance

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