bakit walang positive/negative and A.C.?

[iyo karpo]

regarding sa neutral,,,,hanging ground or kasama siya sa ground thanks.

famous tlga ang red for positive and black sa ground.wiring scheme ko sa lahat ng project ko. standard kaya siya sa lahat?

Red and black - typical sa low voltage DC.

[piona]

sorry po bakt sa dc merong positive and negative sa ac wala?

may polarity din ang ac, when your dealing with power flow sa ac power system, importante ang polarity ng ac   

same sa dc pag-nagkamali ka dito kaboom din 

try reading about phasors ng ac systems 

[bravokilo]

Sir Renn, a little history here.

     When electric generation became known, DC was generated and this was by way of making the alternator switch contacts along its shaft. We call this commutation. The WW2 US army jeep used a 6 volt generator. of course I have to explain to you why the electric polarities reverses. Well, in a very simple alternator, we would have 2 magnets, one S and the other N on opposite ends of the alternator. Imagine a rotor whit 2 poles. as it rotates, the rotor faces N and then S, thus the polarity of the electric current produced changes.  It has been AC all along! Edison insisted on DC and thus many early gensets were producing DC but as I said, it was just switching connections as the generator eally produced AC all along. masny radio radio sets in the uS were labeled AC/DC sets. Perhaps it is because in the early days, enthusiasts experimented with baterries! Comes TESLA. He insisted on AC! He argued against the need for commutation and instead just use slip rings on the gensets, And most importantly AC can be transformed to different voltages via transformers. The latter was so important. Power is VA and we can send the same power with different VA combinations. Today, the bare wirte of Meralco near the top of the posts has   30k volts! If it is carrying 100 amps, that is 30,000 x 100 or 3 million VA or watts or 3000 kva. Why transmit at 30kV. The reason is that thinner cables can be used and it is cheaper! if you ran 3000kva at 220Volts, the wire will be monstrous. See, V is speed. and the electrons are just running faster. So, at every location, a step down transformer yard is used and further down, you see the transformers up in the post. Tesla won the battle.

On you next query about DC in electronics. Well, semiconductors are DC devices. They have polarities. So we have NPN and PNP transistors. o big deal, since a diode can block one pole and create DC where we need it in our devices.

BK