Wheatstone bridge application: A classic Wheatstone bridge circuit can be used to determine an unknown resistance by balancing the bridge and reading a known ratio. Decide whether this statement correctly describes a common use of the bridge.

Introduction / Context:
The Wheatstone bridge is a foundational measurement circuit. By adjusting one known resistor (or using a calibrated ratio), the bridge can be balanced so that the detector indicates zero. At balance, a simple proportion relates the unknown resistor to the known elements, enabling precise resistance measurement without directly reading current or voltage across the unknown at nonzero levels.

Given Data / Assumptions:

• Four-resistor bridge configuration with a sensitive null detector.
• At balance, no current flows through the detector branch.
• Resistors are stable during measurement; temperature effects are negligible.

Concept / Approach:
At balance, the ratio of the two arms is equal: R1/R2 = R_unknown/R3 (labeling may vary). Solving gives R_unknown = (R1/R2) * R3. Because the detector sees near-zero current at balance, measurement error due to detector loading is minimized, making the method precise for a wide range of resistances.

Step-by-Step Solution:

Verification / Alternative check:
Compare the result with a direct ohmmeter reading; close agreement validates proper balancing and resistor tolerances.

Why Other Options Are Wrong:

• Incorrect / AC only / only above 1 kΩ / requires digital meter: The bridge works with DC or AC (for resistive cases) and across broad resistance ranges; a simple galvanometer or null detector is sufficient.

Common Pitfalls:
Miswiring the bridge arms, ignoring lead resistance for low-ohm measurements, or attempting to read the unknown without reaching true null.

Final Answer:
Correct