Unbalanced Wheatstone Bridge voltage across resisitors

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SUMMARY

In an unbalanced Wheatstone Bridge, the voltage across resistors R2 and R4 behaves differently due to the bridge's configuration. The Bridge Balance equation, R1/R2 = R3/R4, indicates that while the voltage across R4 changes with variations in the variable resistor R4, the voltage across R2 remains constant. This is because the current through R1 does not affect the current through R2, thus maintaining a stable voltage across R2 despite changes in R4.

PREREQUISITES
  • Understanding of Wheatstone Bridge circuits
  • Familiarity with Ohm's Law
  • Knowledge of series and parallel resistor configurations
  • Basic principles of electrical current flow
NEXT STEPS
  • Study the implications of the Bridge Balance equation in various circuit configurations
  • Explore the effects of changing resistances in Wheatstone Bridge circuits
  • Learn about Kirchhoff's laws and their application in circuit analysis
  • Investigate practical applications of Wheatstone Bridges in measuring unknown resistances
USEFUL FOR

Electrical engineering students, circuit designers, and anyone interested in understanding the principles of Wheatstone Bridges and their applications in electrical measurements.

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Homework Statement



It is a qualitative problem. No values are given.
In an unbalanced Wheatstone Bridge, does the voltage across the resistors R4 and R2 change? In other words is Vr2of balanced bridge=Vr2 of unbalanced bridge? likewse for R4.

Homework Equations



The Bridge Balance eqn is R1/R2 = R3/R4, where R4 is the variable resistor. At balanced condition, Vr2 = Vr4



The Attempt at a Solution


The change in Vr4 is obvious. My problem was why does Vr2 remain constant??
I assumed that as current flows through R1 - Rg - R4 path, the current through R1 is also changing. But the current through R2 does not change as the extra Ig doesn't come into R2. I thought this was the reason behind Vr2 being constant.

But, the text said "the current through R1 doesn't change with change in R4. Hence, Vr2 does not change" ... How ?? I don't understand.. Is the text trying to say the current in the R1-R2 arm doesn't change at all ? Then what is the path of Ig from the source ??
 
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