How to measure voltage using a DC voltmeter?

Before connecting the DC voltmeter, you must understand the polarity of the voltmeter. Usually, there are two symbols "+" and "-" next to the terminal of the DC voltmeter. The "+" (positive end) of the terminal should be connected to the high potential of the voltage being measured; the "-" (negative end) of the terminal should be connected to the low potential of the voltage being measured. The wiring method is shown in Figure 3-7. The positive and negative poles must not be connected incorrectly, otherwise the instrument pointer will be damaged due to reversal.