What measuring instrument combines several functions into one unit?

The multi-meter is an essential tool in the field of electrical measurements, combining several functions into one compact unit. It is designed to measure voltage, current, and resistance, making it versatile for various applications in circuit diagnostics and electrical troubleshooting. The ability to perform multiple tests with a single device not only simplifies the workflow for technicians but also enhances efficiency, as there is no need to switch between different instruments for basic measurements.

In contrast, a calibrator primarily serves to adjust and verify the accuracy of measuring instruments. A frequency analyzer is specifically designed to measure the frequency of signals, which is a narrower function compared to what a multi-meter offers. A digital thermometer is used solely for measuring temperature. While each of these instruments has its own unique and valuable capabilities, they do not encompass the multifunctional nature that characterizes a multi-meter. This makes the multi-meter the most comprehensive tool among the options presented.