What is the total resistance of an ideal ammeter and an ideal voltmeter?

Answer and explanation

Correct answer: C. An ideal ammeter has 0 ohms resistance; an ideal voltmeter has infinite resistance

  1. Step 1: An ammeter is connected in series with a circuit component to measure current. To avoid reducing the circuit's total current, it must possess zero internal resistance (0 ohms).
  2. Step 2: A voltmeter is connected in parallel across a component to measure potential difference. To prevent drawing current away from the circuit branch, it must possess infinite internal resistance.
  3. Step 3: Identify the ideal meter characteristics.
Answer
An ideal ammeter has 0 ohms resistance; an ideal voltmeter has infinite resistance.
Why not the others: 'Ammeter infinite; voltmeter 0' is the exact opposite and would short-circuit the voltmeter while blocking current through the ammeter; 'Both 1.0 ohm' introduces measurement error; 'Both infinite' would block all current through any circuit containing an ammeter.

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