Wheatstone bridge concept: When a Wheatstone bridge is balanced, what will an ideal center instrument (voltmeter/galvanometer) read across the bridge diagonal?

Introduction / Context:
A Wheatstone bridge is widely used for precision measurement of resistance and for sensing applications (e.g., strain gauges). At balance, the bridge provides a null indication, which makes measurements highly accurate and immune to many error sources.

Given Data / Assumptions:

• Four resistive arms forming a diamond (bridge) network.
• An ideal null detector (voltmeter/galvanometer) connected across the bridge diagonal.
• “Balanced” means R1/R2 = R3/R4.

Concept / Approach:
At balance, the potentials at the two midpoints are equal. With no potential difference between them, the detector sees zero volts. This null method lets you detect tiny changes by rebalancing, rather than reading an absolute voltage directly.

Step-by-Step Solution:

Verification / Alternative check:
Apply superposition or voltage divider equations to each leg; both midpoint voltages evaluate identically under balance, confirming zero differential.

Why Other Options Are Wrong:

• Same/half/twice source voltage: A null detector reads zero at balance; any nonzero reading indicates imbalance.

Common Pitfalls:
Confusing “bridge output” with “source voltage” and overlooking that the bridge measures imbalance, not absolute level.

Final Answer:
zero volts