Physics I / Laboratory Safety and Equipment
Practice question · Multiple choice

A multimeter set to measure current has near-zero internal resistance. What happens if you connect it directly across a battery’s terminals (as if measuring voltage)?

Hints
  1. Ohm’s law with R0R \to 0: what does I=V/RI = V/R do?
  2. Ammeters go in series (current flows through them); voltmeters go in parallel. Swapping the roles swaps the safety.
Show the answer

B. A dangerous short circuit through the meter

Why

An ammeter is deliberately a near-perfect conductor so it won’t disturb the current it measures, placed across a source, it becomes the circuit, and I=V/RI = V/R with tiny RR means a blown fuse at best. Knowing why the rule exists is what makes it stick.

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