Unbalanced Wheatstone Bridge voltage across resisitors

In summary, the conversation discusses a qualitative problem regarding an unbalanced Wheatstone Bridge. The question is whether the voltage across resistors R4 and R2 changes in an unbalanced bridge and whether Vr2 of a balanced bridge is equal to Vr2 of an unbalanced bridge. The relevant equation is the Bridge Balance equation, which states that R1/R2 = R3/R4, and at balanced condition, Vr2 = Vr4. The text discusses the reason for Vr2 remaining constant, with the conclusion that the current through R1 does not change with a change in R4. The conversation also mentions other sources for further information on bridge circuits.
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msslowlearner
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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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FAQ: Unbalanced Wheatstone Bridge voltage across resisitors

What is an Unbalanced Wheatstone Bridge?

An Unbalanced Wheatstone Bridge is a type of electrical circuit that uses four resistors in a diamond shape to measure an unknown resistance. It works by comparing the voltage across two parallel branches of the circuit, with the goal of achieving a balanced condition where the voltage is equal on both sides.

How is the voltage across resistors calculated in an Unbalanced Wheatstone Bridge?

The voltage across a resistor in an Unbalanced Wheatstone Bridge is calculated using the formula V = IR, where V is the voltage, I is the current, and R is the resistance. The voltage is typically measured using a voltmeter.

What causes an Unbalanced Wheatstone Bridge to have unequal voltages across resistors?

An Unbalanced Wheatstone Bridge can have unequal voltages across resistors due to a number of factors, including variations in the resistors' values, fluctuations in the power supply, and errors in measurement. These imbalances can be caused by external factors or by imperfections in the circuit itself.

How can you correct an Unbalanced Wheatstone Bridge?

To correct an Unbalanced Wheatstone Bridge, the circuit must be adjusted until the voltage across the two parallel branches is equal. This can be done by varying the values of the resistors or by adjusting the power supply. In some cases, additional resistors may need to be added to the circuit to achieve balance.

What are the practical applications of an Unbalanced Wheatstone Bridge?

An Unbalanced Wheatstone Bridge can be used in a variety of applications, including measuring unknown resistances, detecting changes in resistance, and calibrating electrical equipment. It is commonly used in laboratory settings and in electronic circuits to measure and compare resistances. It can also be used in strain gauge sensors, which measure the deformation of an object by detecting changes in resistance.

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