What instrument is used to measure power consumption over a specific period of time?

The kilowatt hour meter is the correct instrument for measuring power consumption over a specific period of time. This device quantifies the total energy consumed in kilowatt hours (kWh), which reflects the amount of electrical energy used over time.

In practical terms, it continuously monitors the electrical usage of a facility or appliance and records the cumulative energy consumption. This makes it essential for utilities to bill customers accurately for their electricity use since the cost is typically based on the total energy consumed over a billing period.

Other instruments, such as voltage meters and amperage meters, measure specific electrical properties (voltage and current, respectively) but do not directly quantify energy consumption over time. A thermometer, on the other hand, measures temperature and is unrelated to power consumption. Thus, the kilowatt hour meter stands out as the proper tool for assessing energy use over a designated timeframe.