If the voltage output goes to zero, what will the volt meter read?

When the voltage output drops to zero, the voltmeter will reflect that condition by reading 0 VAC. This is fundamentally because a voltmeter is designed to measure the electrical potential difference between two points. If the voltage being measured is absent—meaning there is no potential difference—the voltmeter can only indicate that no voltage is present. Thus, it shows a reading of 0 VAC. The relationship between voltage and the meter ensures that if there is no voltage to measure, the meter accurately reports that state with a zero reading.

In this context, while power delivery to the meter could be a consideration, it is the voltage that primarily dictates what the voltmeter displays. Therefore, when looking for a reading that accurately represents the absence of voltage, 0 VAC is correct.