The relationship between the current internal resistance of the multimeter and the electric power
Ideally, the internal resistance of the multimeter's current block should be equal to zero. Due to the existence of internal resistance, there must be a certain voltage drop when using a multimeter to measure current, resulting in measurement error.
The smaller the internal resistance of the current block, the lower the electrical power consumed by the multimeter when measuring the current.
1) When the range of the current block is the same, the smaller the internal resistance of the multimeter, the lower the full-scale voltage drop, and the smaller the error of the measured current. For the same multimeter, the full-scale voltage drop value of each current block can be different.
2) For the same multimeter, the larger the current range, the smaller the internal resistance and the smaller the measurement error.
Therefore, in order to reduce the error of measuring the current, sometimes it is better to choose a higher current range. Of course, the range should not be selected too high, so as to avoid a significant increase in the reading error when measuring small currents.
3) When the internal resistance of the current block is about 1% of the total resistance of the circuit under test, it is not necessary to consider the influence of the voltage drop of the multimeter on the measurement.
