Define voltmeter.

Define voltmeter.

• A. Voltmeter is a device used for measuring existing voltage in an electrical system and provides a relative indication of battery condition; with battery on and engine off, it indicates the top voltage and measures drop when accessories are used.
• B. Voltmeter is used to measure water pressure.
• C. Voltmeter measures air flow.
• D. Voltmeter tests hydraulic pressure.

Answer: (A)

A voltmeter measures the electrical potential difference between two points in a circuit. In a pumper apparatus, it’s used to assess the health of the electrical system and battery by showing the actual voltage present. When the battery is off, the voltmeter displays the resting (open-circuit) voltage, which indicates the state of charge. When the engine is running and accessories are in use, it shows the system voltage and any voltage drop caused by the load, wiring, or the charging system. This helps diagnose whether the battery and alternator are functioning properly. The other options don’t fit because they describe instruments for measuring water pressure, air flow, or hydraulic pressure—parameters unrelated to electrical voltage.

A voltmeter measures the electrical potential difference between two points in a circuit. In a pumper apparatus, it’s used to assess the health of the electrical system and battery by showing the actual voltage present. When the battery is off, the voltmeter displays the resting (open-circuit) voltage, which indicates the state of charge. When the engine is running and accessories are in use, it shows the system voltage and any voltage drop caused by the load, wiring, or the charging system. This helps diagnose whether the battery and alternator are functioning properly.

The other options don’t fit because they describe instruments for measuring water pressure, air flow, or hydraulic pressure—parameters unrelated to electrical voltage.