An ammeter must be connected in series and should have

  • A. very high resistance
  • B. very low resistance, so it hardly alters the current it measures
  • C. infinite resistance
  • D. the same resistance as the circuit

Explanation

Since the whole current flows through it, any appreciable resistance would reduce that current and falsify the reading, so an ideal ammeter has zero resistance. A voltmeter is the opposite case: connected in parallel, it should have very high resistance so it draws almost no current from the branch it is measuring. Connecting an ammeter in parallel across a supply is close to a short circuit and can destroy it.

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