Lecture on Capacitor knowledge(III)

Determination of polarity of Electrolytic Capacitor. 
Electrolytic capacitors that do not know the polarity can be measured by the electrical barrier of the multimeter. 
We know that the leakage current of the electrolytic capacitance is small only when the positive electrode of the electrolytic capacitor is positive (the black meter pen in the electric barrier and the negative end of the power supply is negative (the red meter pen in the electric barrier)), the leakage current of the electrolytic capacitor is small (the leakage resistance is large). Conversely, the leakage current of the electrolytic capacitor increases (the drain resistance decreases). 
When measuring, assume that a very "+" pole is connected to the black pen of the multimeter and the other electrode to the red pen of the multimeter. Note the scale at which the watch needle stops (the gauge needle is large against the left resistance, and then discharge the capacitor (both two leads touch the wire, the two watch pens are adjusted, and the measurement is re-measured). In two measurements, the last stop of the gauge needle is the one on the left (with a large resistance), and the black meter pen is connected with the positive electrode of the electrolytic capacitance. 
It is best to use RP100 or RG1K block when measuring. Judging Capacitor quality by Multimeter