2007-09-19 19:54:13 · 7 answers · asked by aryan e 1 in Science & Mathematics ➔ Physics
Whenever an electric current passes through any conductor some amount of power will be lost. By equation this power loss is equal to " I² R " . It is directly proportional to the 'Resistance" and "square of the current". If the transmission takes place with larger current the power loss will be high. Every conductor has got resistance. and the resistance is again proportional to the length. So the only desirable method is to send the power with low current. The power is equal to the product of Volt and current. The current can be reduced by increasing the voltage. This is possible only with AC. Using a transformer the voltage can be stepped up to any higher voltage. Simultaneously the current will be considerably minimised. At the generating station the voltage will be stepped up so that the current is minimised. This high tension voltage is transmitted through long distance conductors . Once it reaches the consumers end again it is stepped down with the help of a step down transformer to the desired voltage like 220 volts or 110 volts.
This stepping up and stepping down is possible only with AC. not with DC. That is why for long distance transmission AC is used.
2007-09-20 02:05:53 · answer #1 · answered by Joymash 6 · 2⤊ 0⤋
Because of voltage loss when using DC over long distances compared to A.C.
Also able to step up A.C. to higher voltages using transformers which means less current which means less I.R. drop. Over long distance transmission lines.
Then step it back down again via transformers. at sub stations for distribution to customers.
When elextricity was first starting to be used it was mainly D.C. and almost every block had to have it's own generator station because of voltage losses..
With A.C. you only need the one generator i.e. powerhouse the you can step the voltage up and down as needed.after transmitting it for long distances.
Transformers and power factor correction capacitors are a lot cheaper to buy and maintain that a multitude of generators.
That brings up the main reason. Cost.! The simple fact is it cost less.
2007-09-20 03:05:15 · answer #2 · answered by JUAN FRAN$$$ 7 · 2⤊ 0⤋
Power losses are proportional to the current. With A.C. extremely high voltages may be used for transmission and converted with little loss to household voltages. With D.C. the either high transmission losses or high conversion losses prevail.
2007-09-20 03:13:11 · answer #3 · answered by armatrag 1 · 1⤊ 0⤋
Because AC is easy to transform.
Ohmic power loss = I^2 R. So if you can minimize the current, you minimize the power lost along the way. The best way to do that is to have your transmission lines be very, very high voltage (and hence lower current for the same power delivered).
Fortunately, AC is easy to transform from low voltage at generation to that high voltage and back down again at the point of use. You can't do that with DC.
2007-09-20 03:03:02 · answer #4 · answered by Anonymous · 2⤊ 0⤋
DC doesn't transmit particularly well. It loses strength very quickly along a line.
AC works much better for distribution. If DC is needed at the destination, usually a converter is the best way to go.
2007-09-20 03:04:39 · answer #5 · answered by Warren D 7 · 1⤊ 0⤋
to maintain direct current thru a conductor a lot of power is dissipated.. thats the main thing
now lets talk about dc and ac.... ac has a positive cycle and a negative cycle in short its an off and on cycle so power is there for half of the time....
on the other hand about dc... power has to be transmitted continuously... so for a fixed voltage and fixed time period.... the power required to maintain a dc is double than that of an ac... i hope u get that..
2007-09-20 03:01:05 · answer #6 · answered by jammy 2 · 0⤊ 1⤋
You will find the biography of Thomas Edison (ex., in wikipedia) interesting--"The current wars"
Edison's company produced direct current for customers. Then came the competition, in the person of Mr. Westinghouse, offering AC.
The "current war" therefrom began.
2007-09-20 03:42:00 · answer #7 · answered by kent☼wn 3 · 0⤊ 1⤋