Why alternatig current electricity is better than direct current?

Answer 1

Nobody said it was. Well, maybe except Nikola Tesla and George Westinghouse... *chuckle*

Each type (AC and DC) has unique advantages over the other in certain situations.

For example - AC is much more useful when transmitting power over distance, as power lost with AC has much more to do with parasitic inductance and capacitance than it does with resistance. AC is also the form in which most of our electricity is generated (electrical generators are turbines, they produce AC). And on top of that, AC is easily manipulated using Transformers, which do their job thanks to alternating magnetic fields (DC doesn't produce an alternating magnetic field).

The main disadvantage of AC would be its lethality to all living creatures, and of course - AC is useless when it comes to state-based electronics. Most AC devices are also rather bulky and impractical to carry around for long.

DC, on the other hand, is much more useful in low-voltage applications where power doesn't need to go far, and wherever logical states are considered. As such, most electronics is mainly DC (with a few notable exceptions throughout the years). Your computer, radio, television set, even your wristwatch - they all run on DC, internally. Yes, the TV set uses DC as well, only at much higher voltages (typically around 180V/320V to start, and then a couple kV to drive the deflection coils and the electron gun).

Then again, DC was dropped in favor of AC when it came to power distribution - and why? Well, as I've mentioned before, DC transmission suffers much higher power losses over distances, as conductor (wire) resistance comes into play - this energy is wasted away as heat. This also limits the effective range of power distribution network to a couple of hundred kilometers (beyond which consumers would receive too little power to be of any use).

So, as it should already be evident, each form has its strong and weak points. None is better than the other - they're both different forms of the same thing - but each is better suited for some applications over others.

I hope this answers your question.