The measurement range and measurement accuracy of the multimeter
Measuring Resistance: First, short-circuit the test leads together to make the pointer deflect to the right. Then, adjust the "Ω" zero-adjustment knob so that the pointer points exactly to 0. After that, touch the two test leads to the two ends of the resistance under test (or the circuit), read the reading of the pointer on the ohm scale (the first scale), and then multiply it by the number marked on this range. The result is the resistance value of the measured resistance. For example, when using the R100 range to measure a resistance and the pointer points to 80, the measured resistance value is 80100 = 8K. Since the readings on the left part of the "Ω" scale are relatively dense and difficult to read accurately, an appropriate ohm range should be selected during measurement. Try to make the pointer be in the middle or right part of the scale, so that the reading will be clearer and more accurate. Every time the range is changed, the two test leads should be short-circuited again, and the pointer should be adjusted to the zero position to ensure accurate measurement.
Measuring DC Voltage: First, estimate the magnitude of the DC voltage to be measured. Then, turn the change-over switch to an appropriate V range. Connect the positive test lead to the "+" terminal of the measured voltage and the negative test lead to the "-" terminal of the measured voltage. Then, according to the number on the scale marked with the DC symbol "DC-" (the second scale) and the position of the pointer, read out the magnitude of the measured voltage. For example, when using the V300 range to measure, you can directly read the value within the range of 0-300. When using the V30 range to measure, just remove one "0" from the number 300 on the scale, regard it as 30, and also regard the numbers 200, 100, etc. as 20, 10 respectively, and then you can directly read the value indicated by the pointer. For example, when measuring the DC voltage with the V6 range and the pointer points to 15, the measured voltage is 1.5 volts.
Measuring DC Current: First, estimate the magnitude of the DC current to be measured. Then, turn the change-over switch to an appropriate mA range, and connect the multimeter in series in the circuit, as shown in the figure. At the same time, observe the scale marked with the DC symbol "DC". For example, when the current range is set to the 3mA range, remove two "0"s from the number 300 on the surface scale, regard it as 3, and also regard the numbers 200, 100 as 2, 1 respectively. In this way, the value of the measured current can be read out. For example, when measuring the DC current with the DC 3mA range and the pointer is at 100, the current is 1mA.
Measuring AC Voltage: The method of measuring AC voltage is similar to that of measuring DC voltage. The difference is that since there is no positive or negative distinction for alternating current, there is no need to distinguish between positive and negative for the test leads when measuring AC. The reading method is the same as that for measuring DC voltage, but the position of the pointer should be read on the scale marked with the AC symbol "AC".
