alleryStart learning →What defines a null measurement?
AIt reads the meter only at its zero mark point
BIt balances the load against the battery emf
CIt uses two meters at once for a cross-check
DIt balances the circuit so no current reaches the meter
Answer & Solution
Correct answer: D. It balances the circuit so no current reaches the meter
1. Ordinary meters take a share of current, and that share is what spoils the reading.
2. A null method adjusts the circuit until the detector carries no current at all.
3. With no current through it, the detector can no longer alter what it is measuring.
4. The reading then comes from the balancing setting rather than from a deflection on a scale.
_Source: OpenStax College Physics (CC BY 4.0), Ch 21 "Circuits and DC Instruments", section 21.5 Null Measurements_
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