Identify the Polarity Of D.C. and A.C.

How To Identify the Polarity Of D.C.  and  A.C.  Supply

1.  Water Test  :--

Dip the leads from the two terminal into water. If the supply is A.C. as bubbles will comes out from both the ends. On the other hands if it is D.C. supply, the bubbles will rise on negative terminal double  of the positive.

2.  Damp Pole Finding Test :-

Lay the terminal leads 2.5 cm apart on damp pole finding paper laid on wood. If one end turns red , it is negative pole of D.C. supply . On the other hands, if both ends turns red then it is A.C. supply.

3.  Potato slice Test :-

Place the two terminal leads on sliced potato. If one end changes green back it is positive terminal of D.C. Again when both Ends turns green black the supply is A.C.