# Questions about AC and DC

1. Jun 24, 2013

### R0nin

Hey guys! Novice physics scholar here who's studying electronics on his downtime. I have some questions concerning AC and DC. If you guys could answer them (simplistically please, I still have a lot to learn :P) I'd really appreciate it.

I'm reading here that 'AC costs less to generate then DC'. Why is that? If anything, I'd think that DC would be cheaper and easier to use. After all, wouldn't it require MORE energy to constantly alternate the direction of a current, as opposed to simply letting a current run a direct course, as it does in DC?

Now, new question... AC current DOES typically generate MORE energy then DC, right? Since the direction of current is constantly being mixed up, the SAME electrons end up travelling a FARTHER distance. Whereas in DC, because the direction of current is so linear, it would seem as if the electrons reach the opposite battery terminal far more quickly then they would in AC, thus lending a shorter 'current life' to DC then to AC. In other words, if you have a 10 V AC battery and a 10 V DC battery, the AC battery would last far longer then the DC.

Am I correct here? Or am I just not making any sense at all?

2. Jun 24, 2013

### mrspeedybob

AC costs less to generate because the simplest and most efficient generator designs are AC designs but that is not the primary reason that power companies distribute AC. The primary reason is that AC voltage can be easily stepped up and down using transformers. High voltage power can be transmitted long distances with low losses, but is too dangerous for household use. Using AC makes it easy to step the voltage down to a less dangerous level when it reaches the consumers.

No. AC motors are simpler and more efficient for the same reasons that AC generators are simpler and more efficient but AC does not inherently pack more punch.
The AC sources you are familiar with are household circuits that are either 110 or 220 volts. The most common DC sources are batteries that range from 1.5 to 12 volts. The AC sources are more potent but it is because the voltages are higher, not because they are AC. 110 volts DC would be just as potent as 110 volts AC.

I don't and neither does anyone else. There is no such thing as an AC battery.

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