1. A multimeter is our commonly used testing tool

2. Voltage measurement method using a multimeter

The voltage measurement method using a multimeter first requires aligning the range switch within the five range marked with V (for testing AC voltage, align it with the AC voltage range, and for testing DC voltage, align it with the DC voltage range). When measuring voltage, the meter probe should be connected in parallel to the circuit being tested. Select a suitable range position based on the approximate value of the circuit being tested. The maximum value of each dry battery cell is 1.5V, so it can be placed in the 5V range. At this point, 500 of the full scale reading on the panel should be taken as a reading of 5. That is, shrink by 100 times. If the watch needle points at the 300 scale, it reads 3V. Note that the value indicated by the tip of the range switch is the corresponding value of the full scale reading of the needle on the meter head. When reading the meter, simply convert it accordingly to read the real value. Except for the resistance range, all range switches should read the measurement results using this method. In actual measurement, when the approximate value of the measured voltage cannot be determined, the switch can be turned to the maximum range first, and then the range can be reduced to the appropriate position step by step. When measuring DC voltage, attention should be paid to the positive and negative polarity. If the probe is connected in the wrong direction, the probe will strike back. If you don't know the positive and negative polarity of this circuit, you can set the multimeter range to the maximum range and quickly try it on the circuit under test. By observing how the stylus is deflected, you can determine the positive and negative polarity.

3. Measure 220V AC power
Turn the range switch to the AC 500V position. At this point, the full scale is 500V, and the reading is read according to the scale 1:1. Insert two probes into the power socket, and the voltage value measured is at the scale indicated by the probe. When measuring AC voltage, the probe does not have a positive or negative distinction.