What type of meter would you use to measure voltage across a component?

To measure voltage across a component, a voltmeter is the appropriate tool. A voltmeter is specifically designed to measure the electrical potential difference between two points in an electrical circuit. It is connected in parallel with the component whose voltage you want to measure. This configuration allows the voltmeter to measure the potential difference without significantly affecting the circuit's behavior, as it has a very high input impedance.

In contrast, an ammeter is used to measure current and must be connected in series with the component, which is not suitable for measuring voltage. An ohmmeter measures resistance in ohms and is used when testing the resistance of a circuit or component, also not directly measuring voltage. A wattmeter measures power in watts, which involves both voltage and current but is not used specifically for measuring just voltage. Thus, the voltmeter is the only tool among the options that fulfills the requirement of measuring voltage across a component accurately.