Here's an interesting one for you!
If 240v ac mains is a perfect sine wave, how come it has a positive and negative?, since both parts of the waveform exist for the same amount of time on each wire !
240v and positive and negative ??
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It doesn't really have a positive and a negative. What it really has is neutral (called negative) and Sine wave (called positive). Neutral is tied to earth, and so doesn't have a sine wave on it. "Positive" actually swings between +340V and -340V 50 times a second, where the RMS (root-mean-square) of this waveform is 240v, hence 240VAC quoted for UK power.
At least I think I remember that correctly... it's been about 15 years since I was taught that at school.
At least I think I remember that correctly... it's been about 15 years since I was taught that at school.
That's right[:)]
The 'positive' is correctly called 'phase'.
The 'negative' is tied to ground <i>somewhere</i>, but depending on the system this can be some distance away, and it can actully be found to float well above ground level, so never assume that it's dead!
BTW, mains is very rarely a <b>perfect</b> sine wave - it's usually quite heavily distorted, mostly be devices which only consume part of each cycle.
The 'positive' is correctly called 'phase'.
The 'negative' is tied to ground <i>somewhere</i>, but depending on the system this can be some distance away, and it can actully be found to float well above ground level, so never assume that it's dead!
BTW, mains is very rarely a <b>perfect</b> sine wave - it's usually quite heavily distorted, mostly be devices which only consume part of each cycle.