alleryStart learning →How do ordinary meters disturb the circuit they are reading?
AVoltmeters draw extra current, ammeters cut it
BVoltmeters cut the current, ammeters draw extra
CBoth of them add current to the branch measured
DBoth of them remove current from the branch
Answer & Solution
Correct answer: A. Voltmeters draw extra current, ammeters cut it
1. A voltmeter is an extra parallel branch, so it opens a new path and draws additional current.
2. An ammeter is an extra series element, so it adds resistance and reduces the current in that branch.
3. The two errors therefore pull in opposite directions rather than in the same direction.
4. Both effects are shrunk, but never removed, by making voltmeters high in resistance and ammeters low.
_Source: OpenStax College Physics (CC BY 4.0), Ch 21 "Circuits and DC Instruments", section 21.5 Null Measurements_
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