Which is a common application of a voltmeter?

A voltmeter is specifically designed to measure the electric potential difference, or voltage, across two points in an electrical circuit. This makes it particularly useful for checking battery voltage levels, as it provides a direct reading of the voltage that the battery is supplying. Knowing the voltage of a battery can help determine its state of charge or if it needs replacing. When a voltmeter is connected to a battery, it allows users to assess whether the voltage is within the expected range for that battery type.

In contrast, measuring resistance values generally involves using an ohmmeter, which is not the primary function of a voltmeter. Calculating the total power output involves knowing both voltage and current, and while voltage measurements can contribute to this, the voltmeter cannot perform the calculation on its own without additional data. Similarly, testing for short circuits requires identifying continuity or determining if current can flow freely, which is typically done using a different type of testing equipment. Thus, using a voltmeter for checking battery voltage levels is the most suitable and common application among the available choices.