Which type of meter movement operates as a direct result of current flowing through a wire?

The correct choice is the thermal meter movement. This type of meter operates based on the heating effect of electric current. As current flows through a conductor, it generates heat due to its resistance. In thermal meters, this heat causes a thermal element to expand, and the degree of expansion is proportional to the amount of current flowing. This principle is used to measure and display energy consumption in kilowatt-hours or similar units.

Thermal meter movements are particularly significant in applications where the measurement of power consumption is required, as they can provide accurate readings over a wide range of currents. The response time of thermal meters may be slower than other types due to the time required for heating and thermal expansion, but they remain a reliable method of power measurement.

In contrast, electromagnetic meters rely on the interaction between magnetic fields generated by the current and mechanical components, while moving coil meters use the magnetic field produced by the current flowing through a coil. Digital meters, on the other hand, convert analog signals to digital for display rather than working directly on the principle of current heating a wire.