A voltmeter is used to measure voltage in a circuit by connecting in parallel to a component.

A voltmeter is used to measure voltage in a circuit by connecting in parallel to a component.

• A. Connected in parallel to a component
• B. Connected in series with a component
• C. Placed across the power supply only
• D. In the main circuit path

Answer: (A)

A voltmeter measures the potential difference between two points, so to know the voltage across a specific component you place it so its two terminals touch the two points of the component. This puts the meter in parallel with the component, meaning it measures the same voltage that appears across the component. The voltmeter is designed with very high internal resistance, so only a tiny current flows through it and it hardly affects the circuit; the reading reflects the component’s voltage accurately. If the voltmeter were in series with the component, it would become part of the circuit and its large resistance would distort current and voltage distribution, giving an incorrect reading for the component’s voltage. Placing it across the power supply would measure the supply voltage, not necessarily the voltage across the component, and “in the main circuit path” implies a series connection, which again would alter the circuit and the reading.

A voltmeter measures the potential difference between two points, so to know the voltage across a specific component you place it so its two terminals touch the two points of the component. This puts the meter in parallel with the component, meaning it measures the same voltage that appears across the component. The voltmeter is designed with very high internal resistance, so only a tiny current flows through it and it hardly affects the circuit; the reading reflects the component’s voltage accurately.

If the voltmeter were in series with the component, it would become part of the circuit and its large resistance would distort current and voltage distribution, giving an incorrect reading for the component’s voltage. Placing it across the power supply would measure the supply voltage, not necessarily the voltage across the component, and “in the main circuit path” implies a series connection, which again would alter the circuit and the reading.