Multimeter measuring resistance black head pin inserted in the meter on what pole
The multimeter head is a sensitive magneto-electric DC ammeter (microammeter). When using a multimeter to measure, first set the gear and range, then the red pen is inserted into the corresponding jack, and the black pen is inserted into the common end jack.
When measuring resistance with a multimeter, gear to "Ω" file, select the appropriate range, the head will be connected in parallel and series with the appropriate resistance, while a battery in series, so that the current through the measured resistance, according to the size of the current, you can measure the resistance value. When measuring, there is no "+" or "-" polarity for resistors. However, when measuring crystal diodes, electrolytic capacitors and other components with polarity, you must pay attention to the polarity of the pen.
Measurement of AC voltage with a multimeter, although the head is a magnetoelectric DC ammeter, will be adjusted to the "AC ~" file to measure the AC voltage, it will be installed a parallel, series half-wave rectifier circuit, AC rectification into DC and then through the head, so that you can measure the AC voltage through the size of the DC current. Therefore, when measuring AC voltage, as long as you choose the appropriate range, red and black pens have no contraindications.
When measuring DC current and DC voltage with a pointer multimeter, pay attention to the "+" and "-" polarity. If the pointer is found to be reversed, the pen should be immediately replaced to avoid damage to the pointer and the head. However, when measuring DC current and DC voltage with a digital multimeter, if the polarity is reversed, there is no big problem, only the display shows negative values.
The standard practice is to insert the red pen into the V / Ω this hole, the black pen into the common terminal COM this hole, so that the voltage and resistance can be measured!
In fact, if it is a digital multimeter, you reversed, can also be measured, the resistance has no polarity, the voltage is reversed on the display of negative values only.
If it is an analogue meter, the resistance can also be inserted into the opposite pen, just be careful when measuring DC voltage, the pen may burn off the head anyway!
