Which action describes why voltmeters are connected in parallel to measure voltage?

Which action describes why voltmeters are connected in parallel to measure voltage?

• A. Because they measure current
• B. Because they measure voltage across the component
• C. Because they drop the voltage to zero
• D. Because they are cheaper

Answer: (B)

Voltage is the potential difference between two points, so to measure the voltage across a component you must connect the voltmeter across the two terminals. A voltmeter has very high internal resistance, so when connected in parallel it draws little current and does not significantly change the circuit. This arrangement makes the meter read the same potential difference that exists across the component. If it were placed in series, it would carry the circuit current, introduce a large voltage drop, and the reading would not reflect the component's voltage.

Voltage is the potential difference between two points, so to measure the voltage across a component you must connect the voltmeter across the two terminals. A voltmeter has very high internal resistance, so when connected in parallel it draws little current and does not significantly change the circuit. This arrangement makes the meter read the same potential difference that exists across the component. If it were placed in series, it would carry the circuit current, introduce a large voltage drop, and the reading would not reflect the component's voltage.