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A digital multimeter (DMM) is a testing tool that measures electrical values: current in amps, voltage in volts and resistance in ohms. Electricians use a digital multimeter as a standard diagnostic tool. Digital multimeters essentially replaced analog meters that were used prior to the 1970s and used needles to indicate values. The digital counterpart has proven to be more accurate, reliable and has increased impedance compared to its former counterpart. They also combine testing capabilities that were earlier limited to separate voltmeters, ammeters and ohmmeters. Many modern multimeters also have special additional features.
The face of a digital multimeter usually has four components:
Counts and digits are the terms that define a digital multimeter’s resolution. By knowing the proper resolution, a technician knows whether the multimeter can detect a certain signal. For example, if a multimeter offers 1mV on a 4V range, one can see a change of 1mV when reading 1V. Digital multimeters also offer additional testing capabilities like frequency, capacitance and temperature. A multimeter has various purposes; for example, it can be used as a handheld device for field work or it can also be used to measure data in a controlled environment with high accuracy. All modern digital multimeters have embedded computers, providing added features like auto-ranging, sample and hold and auto-polarity.