Electric meter, instrument for measuring the consumption of electricity. Domestic electric meters register the quantity of electricity used in the home in kilowatt-hours (KwH). The meter contains a metal disk that rotates in a magnetic field produced by an electromagnet inside the meter. The greater the rate at which power is consumed, the faster the disk rotates. The disk is connected to the dials of the meter through a train of wheels. The amount consumed is periodically read by an official of the electricity company. Other electric meters used to measure the various factors of an electric current, such as ammeters, voltmeters, wattmeters, and ohmmeters, depend mostly on electromagnetism. Some electric meters combine all these instruments in one large instrument that can be switched from one kind of measuring operation to another.