Precautions for measuring small resistance with multimeter
Precautions for the multimeter measuring small resistance, the relationship between the deflection angle of the pointer and the resistance to be measured, when measuring the resistance with the multimeter, in order to ensure the accuracy of the measurement, when measuring the small resistance, it is necessary to shift the gear, try to make the pointer near the center position .
Multimeter to measure small resistance
The multimeter should make the pointer near the center position to measure the small resistance!
When the multimeter measures resistance, the measured value reflected to the meter head is actually the corresponding current passing through the measured resistance. The larger the measured resistance, the smaller the current, that is, the smaller the deflection angle.
The relationship between the deflection angle of the pointer and the measured resistance:
α=(RZθ)/(RX+RZ)
In the formula: α---pointer deflection angle;
RZ——The central resistance value of the multimeter;
RX-----measured resistance; from: electrician world
θ---the angle when the pointer is fully deflected, this angle is mostly 90°
It can be seen from the ohm scale of the multimeter that the scale is an uneven reverse scale. The smaller the deflection angle, the greater the indicated resistance value.
The resistance value between each scale line at the high resistance end is very different. If you look at the pointer at an angle on this section of the scale line during measurement, it will cause a big error.
Especially when measuring small resistance, the error is more obvious.
Therefore, in order to ensure the accuracy of the measurement, when measuring the small resistance, the pointer should be as close as possible to the center position by shifting gears.
