What device is used to measure the total amount of electric energy consumed over time?

The device used to measure the total amount of electric energy consumed over time is the watthour meter. This instrument specifically tracks energy usage in watt-hours, providing a cumulative count of energy consumption within a specific timeframe.

Unlike other devices, a voltmeter measures the electrical potential difference between two points, which does not relate directly to energy consumption over time. An ammeter is used to measure the flow of electric current in amperes, while an ohmmeter measures electrical resistance in ohms. These devices provide valuable information about various aspects of electricity and circuits, but they do not quantify energy consumption, making the watthour meter the appropriate choice for measuring total electrical energy used.