A voltmeter is used by attaching the positive and negative terminals of the voltmeter to the respective ends of the circuit to be tested and reading the results. Usually, the positive terminal of a voltmeter is red, and the negative terminal is black.Continue Reading
Before attaching the voltmeter to the circuit, find out whether the current in the circuit is direct current, DC, or alternating current, AC. Make sure that the voltmeter in use is compatible with the current. If the voltmeter can be adjusted for both type of currents, then set it accordingly before proceeding.
After making sure that the voltmeter is compatible with the current of the circuit, adjust the voltmeter for the range of voltage to be measured. Voltmeters usually have a dial that adjusts and sets the range of voltage. Adjust it prior to connecting the voltmeter with the circuit.
Voltmeters have two terminals. Usually the red cable is positive, and the black cable is the negative terminal. Attach the positive terminal to the positive end of the circuit and the negative terminal to the negative end. Voltmeters run automatically after attaching the cables, and the difference in voltage between the two ends is shown on the display screen. If the voltmeter is analog, the result needs to be read off a scale, and if it's a digital one, the result is shown directly on the display screen.