Voltmeters

Definition

Voltmeters are instruments used to measure the electrical potential difference, or voltage, between two points in an electric circuit. They are connected in parallel with the component across which the voltage is to be measured.

5 Must Know Facts For Your Next Test

1. Voltmeters have high internal resistance to minimize the current drawn from the circuit being measured.
2. They must be connected in parallel with the component whose voltage is being measured.
3. The accuracy of a voltmeter can be affected by its internal resistance and the impedance of the circuit.
4. Digital voltmeters provide more precise readings compared to analog voltmeters due to their higher resolution and reduced parallax error.
5. A voltmeter can only measure DC voltage if it is designed for DC; otherwise, it will give incorrect readings or might get damaged.

Review Questions

• Why must a voltmeter be connected in parallel with the component it's measuring?
• How does internal resistance of a voltmeter affect its accuracy?
• What are some advantages of using digital voltmeters over analog ones?

Related terms

Ammeter: An instrument used to measure electric current in a circuit, typically connected in series with the load.

Ohmmeter: A device used to measure electrical resistance, usually featuring two probes that connect across a resistor or component.

Impedance: $Z$, the total opposition that a circuit presents to alternating current, including both resistance $R$ and reactance $X$.