Relationship between deflection angle of resistance pointer and resistance measured by multimeter
Relationship between deflection angle of resistance pointer and resistance measured by multimeter
Attention should be paid to when measuring resistance:
1. The measured resistance should be removed from the circuit before measurement.
Don't touch the two pens for a long time.
3. Two hands should not touch the metal rods of two probes or the two pins of the measured resistance at the same time. It is best to hold two probes with the right hand at the same time.
4. If the ohm gear is not used for a long time, the battery in the table should be taken out.
When the multimeter measures resistance, the measured current reflected in the meter 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 pointer deflection angle and measured resistance is as follows:
α=（RZθ）/（RX+RZ）
Where: α-deflection angle of pointer;
RZ－－- multimeter center resistance;
RX－－- measured resistance;
θ-the angle when the pointer is fully deflected, which is mostly 90.
It can be seen from the ohm scale of multimeter that its scale is uneven reverse scale, and the smaller the deflection angle, the greater the indicated resistance. There is a great difference in the resistance between each graduation line at the high resistance end. If you look at the pointer at an angle on this graduation line during measurement, it will cause great errors. Especially when measuring small resistance, the error is more obvious. Therefore, in order to ensure the accuracy of measurement, when measuring small resistance, we should try to make the pointer near the center position by shifting gears.
