1, resolution, number of words and bits
Resolution refers to the resolution of small signals when measuring with a multimeter. Knowing the resolution of the multimeter can determine whether it can observe a small change in the measured signal. For example, if the resolution of the digital multimeter is 1mV in the 4V range, it means that it can observe the change of 1mV (1/1000 V) when reading 1V.
If you have to measure the minimum length of 1/4 inch (or 1 mm), then you won't buy a ruler with a minimum scale of 1 inch (or 1 cm). If the normal temperature is 98.6 degrees Fahrenheit, a thermometer that can only measure whole degrees is of little use. You need a thermometer with a resolution of 0.1 degrees.
A {{0}}digit multimeter can display three whole digits (0 to 9) and a "half digit" (only a "1" is displayed or left blank). The display resolution of a 3-digit multimeter is 1,999 words higher. The display resolution of a 4-digit multimeter is as high as 19,999 words. Compared with "bit", using "word" can describe the discrimination rate of multimeter more accurately. The resolution of the current 3-digit multimeter may be as high as 3,200, 4,000 or 6,000 words.
For some measurements, the 3,200-word multimeter can provide better resolution. For example, if a voltage of 200V or higher is to be measured, a 1,999-word multimeter cannot measure 0.1V V.. While a 3,200 multimeter can display 0.1V when measuring the voltage up to 320V. This resolution is the same as that of the more expensive 20,000-word multimeter before the voltage of 320V is exceeded.
2. Accuracy
The accuracy of digital multimeter is usually expressed as a percentage of reading. Accuracy is 1 percent of the reading, and if the displayed reading is 100V, the actual voltage value may be any value between 99V and 101V V..
The technical parameters may also include a bit range added to the basic accuracy parameters. This range represents the number of words that the rightmost digit of the displayed value may change. In this way, the accuracy in the above example can be expressed as "(1 percent plus 2)". Therefore, if the displayed reading is 100V, the actual voltage value will be between 98.8V and 101.2V V..
The parameters of analog multimeter are determined by full-scale error, not by the percentage of displayed reading. The typical accuracy of analog multimeter is 2 percent or 3 percent of full scale. At 1/10 full scale, the accuracy becomes 20 percent or 30 percent of the reading. The typical basic accuracy of digital multimeter is based on the reading between (0.7 percent plus 1) and (0.1 percent plus 1) or better.
3. Ohm's Law
4, digital and analog display
