Why ac Power
Most recent answer: 10/22/2007
Q:
I was looking up your question on "transformers" and the answer stated that we use AC power because transforming DC power was cumbersome. I believe this to be incorrect. I believe that we use AC power for two reasons: (i) A generator naturally produces AC power (it would be harder to make a DC generator). (ii) AC power (and higher voltages) necessarily leads to less loss through resistance in wires.
Just thought this minor correction might be helpful to someone.
- Simon Gilmour (age 26)
Teacher, NZL
- Simon Gilmour (age 26)
Teacher, NZL
A:
Actually, we stand by our answer.
I don’t think it’s especially hard to make dc generators, since dc motors are fairly cheap. (A motor is a generator run in reverse.) Also, if I remember right, cars used to use dc generators.
Your second point- that high voltages allow the use of low currents and hence less resistive loss- is of course correct. However, that would be true for either ac or dc. The point is that for ac it’s easy to use a transformer and, without much power loss, reduce that high line voltage to convenient house voltage.
mike w
I don’t think it’s especially hard to make dc generators, since dc motors are fairly cheap. (A motor is a generator run in reverse.) Also, if I remember right, cars used to use dc generators.
Your second point- that high voltages allow the use of low currents and hence less resistive loss- is of course correct. However, that would be true for either ac or dc. The point is that for ac it’s easy to use a transformer and, without much power loss, reduce that high line voltage to convenient house voltage.
mike w
(published on 10/22/2007)