The basic principle of a multimeter is to use a sensitive magnetoelectric DC ammeter (microammeter) as the meter head. When a small current passes through the meter head, there will be a current indication. However, the meter head cannot pass large current, so it is necessary to shunt or reduce voltage by connecting some resistors in parallel or series on the meter head to measure the current, voltage, and resistance in the circuit.

A multimeter can be used not only to measure the resistance of the object being measured, but also to measure AC and DC voltages. Some multimeters can even measure the main parameters of transistors and the capacitance of capacitors. Fully mastering the use of a multimeter is one of the most basic skills in electronic technology. Common multimeter types include pointer type multimeter and digital multimeter. The pointer type multimeter is a multifunctional measuring instrument with a meter head as the core component, and the measured value is indicated and read by the pointer on the meter head. The measured values of the digital multimeter are directly displayed in digital form on the LCD screen, making it easy to read, and some also have a voice prompt function. A multimeter is an instrument that shares a common meter head and integrates a voltmeter, an ammeter, and an ohmmeter.