What is the internal resistance of the current gear of the multimeter?
In terms of microamps, a high-sensitivity meter is required, and the internal resistance of the meter is very high, ranging from a few ohms to dozens of ohms, or even hundreds of ohms.
The internal resistance of the mA gear is much lower, within a few tens of ohms, and the internal resistance of the ampere gear is extremely low. Most of the short-circuit shunts are connected in parallel, and the internal resistance is within 1 ohm.
The internal resistance of each gear is quite different.
The microammeter can expand the range by connecting the resistance in parallel. It can be seen that for the same meter, the larger the extended range, the smaller the equivalent internal resistance presented.
The shunt resistance can be calculated through the full bias current of the meter and then according to the required current range. The resistance value of the shunt resistor and the internal resistance of the meter in parallel is the answer you want. R total = (R points XR table) ÷ (R points + R table)
Approximate resistance values can also be obtained by direct measurement with a high-digit digital meter.
