Critical Resistance Measurement Precautions with a Multimeter
A multimeter is a commonly used electronic measuring instrument for measuring basic electrical parameters such as voltage, current, and resistance. When measuring resistance with a multimeter, certain precautions and correct methods are also required to obtain accurate results. The following will introduce the precautions and reading methods for measuring resistance with a multimeter.
Precautions: First, ensure that the circuit under test is in a powered-off state to avoid short circuits and excessive current during the measurement process, in order to ensure safety.
Measurements are conducted using a suitable resistance range. Generally, the resistance ranges of a multimeter include 200 ohms, 2 kiloohms, 20 kiloohms, 200 kiloohms, etc. Choosing the appropriate range can ensure more accurate measurement results. When switching ranges, operate carefully to avoid damaging the probes or causing other errors.
To eliminate other charges generated by the circuit under test and avoid the effects of voltage mutual suppression or resonance phenomena, a resistor wrapped around a finger can be used to short-circuit the circuit, transferring the charges to the finger. Afterwards, measurements can be taken.
The probes of the multimeter should make firm contact with the circuit contacts to ensure the stability of resistance measurements. You can
gently twist the probes to ensure good contact.
When necessary, special treatments should be applied to the circuit under test, such as discharging capacitors and disconnecting connections between metal components, in order to eliminate measurement errors.
Reading method:
Turn on the multimeter, select the resistance measurement range, and choose the appropriate range by referring to the precautions mentioned earlier.
Connect the red and black probes to the two ends of the resistor under test, ensuring that there is no other resistance between the probes and the resistor that could affect measurement accuracy.
Wait for a period of time until the readings stabilize, so as to obtain relatively accurate measurement results. If the probe is touching a thermoelectric sensitive element or measuring resistance near a strong magnetic field, it is necessary to wait even longer to ensure that the effects of thermoelectric potential and magnetic field are eliminated.
Pay attention to the precise location of the reading, and take the position closest to the indicated value as the measurement result. Usually, there is an indicator arrow on the multimeter pointing to the reading value. Sometimes, the reading may have a decimal point indicating the number of decimal places.
To improve measurement accuracy, multiple measurements of the resistance can be taken, and the readings can then be averaged.
By following the aforementioned precautions and reading methods, we can correctly use a multimeter to measure resistance and obtain relatively accurate results. Of course, for some special occasions and specific resistors, there may be some other special requirements and usage methods, which need to be followed according to the specific situation.
