Well,actually continuity tester yan. However, since a DC voltage is used, magkakaroon talaga ng polarity. For example, if instead of the meer, we put an incandescent bulb. Then nakaseries ng 1.5V battery. We will have a crude continuity tester, di ba? kapag may contact yung tinetest, ilaw. Walang issue ang polarity. kahit baliktarin and probes, sindi pa rin. ow, if the part nder test is a diode, we will soon observe na hinde pala pwede baliktarin ang probes. so, we color the probe red where the positive line is and black for the other end. So, in testing a diode, we know we have to inject the plus towards the arrow(sa walang band ng diode). Yung black probe sa may band. Dapat sumindi. Kapag nireverse and probes, dapat hinde sumindi. Kung sumindi, shorted and diode. Kung hinde sumisindi either way, OPEN ang diode.