Question

Why should a voltmeter have a high resistance and an ammeter a low resistance?

Answer 1

Step 1: Voltmeter

1. Voltmeter is a device used to measure potential difference across two points and is connected in parallel.
2. A voltmeter should have very high resistance because to measure the potential difference, all the current should pass through the resistor and no current should pass through voltmeter for precise readings.
3. The current will divide and travel through the voltmeter if the voltmeter has a low resistance and will then give faulty readings.

Step 2: Ammeter

1. Ammeter is device used to measure current and is connected in series.
2. To measured accurate current, there must be no change in current of the circuit by the use of ammeter in series in the circuit.
3. This is possible only when ammeter has very low resistance.

Hence, voltmeter have very high resistance, and an ammeter have low resistance for accurate measurement of potential difference and current should be used.