Final answer:
A voltmeter is used to measure voltage and an ohmmeter is used to measure resistance, both essential for checking proper values in electrical circuits.
Step-by-step explanation:
The instrument used to check proper voltage is a multimeter, which often functions both as a voltmeter and an ohmmeter. A voltmeter measures the potential difference, or voltage, between two points in an electric circuit, which is crucial for ensuring that the circuit functions correctly. For instance, Figure 21.15 illustrates how two different types of battery testers measure terminal voltage, which is an application of a voltmeter. Meanwhile, an ohmmeter is used to measure electrical resistance in a circuit, as per Ohm's law (V = IR).
A voltmeter has a symbolic representation that is standard in electrical diagrams but can come in various forms, such as the large and small devices used aboard the USS Nimitz or on small batteries, as depicted in the images provided. When connecting a voltmeter to check the voltage across a battery or another component, proper use and configuration are essential for accurate readings. Likewise, using an ohmmeter involves applying a specified voltage to measure the current and calculate resistance. Advanced knowledge of these instruments and their proper application is integral for professionals working with electrical systems, especially in engineering and technical fields.