Revisiting the Wheatstone Bridge: A Critical Analysis of Theoretical Validity vs. Practical Constraint in HighResistance Metrology

This paper critically re-examines the widely taught assertion that the Wheatstone bridge cannot be used to measure very high electrical resistances. It argues that this claim conflates practical measurement limitations with theoretical impossibility. By analyzing the bridge balance equation, sensitivity degradation, parasitic leakage currents, and noise effects, the study demonstrates that no fundamental theoretical restriction exists on the measurable resistance range. The paper further reviews advanced metrological adaptations—particularly guarding techniques and specialized megohm bridges—that successfully extend the Wheatstone bridge principle into the gigaohm and teraohm regimes. Finally, the work discusses the pedagogical implications of imprecise language in physics education and advocates for a clearer distinction between ideal theory and engineering constraints.